A determination of the correlation between glycemic levels and the estrous cycle in the white rat

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1 University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1954 A determination of the correlation between glycemic levels and the estrous cycle in the white rat Floyd Hunter The University of Montana Let us know how access to this document benefits you. Follow this and additional works at: Recommended Citation Hunter, Floyd, "A determination of the correlation between glycemic levels and the estrous cycle in the white rat" (1954). Graduate Student Theses, Dissertations, & Professional Papers This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact scholarworks@mso.umt.edu.

2 A DETERMINATION OF THE CORRELATION BETWEEN GLÏCEMXC LEVELS AND THE ESTRCÜ3 CYCLE IN THE WHITE RAT b / FLÜÎÛ HUNTER B. A., P a rk C o lle g e, 1950 P re s e n te d in p a r t i a l f u l f i l l m e n t o f th e re q u ire m e n ts f o r th e d e g ree o f Jyiaster o f A rts MONTANA STATE UNIVERSITY 1954 A pproved by: C ^ h a iri^ i^ Board o f E xam iners a i J L ^ b e a n, G ra d u ate' -School D ate

3 UMI Number: EP37466 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI* Oiasartation PuUiahing UMI EP37466 Published by ProQuest LLC (2013). Copyright in the Dissertation held by the Author. Microform Edition ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code P r o Q ^ s t ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml

4 V ' - \ ACKNOwLEDGEKSKT I sh o u ld l i k o t o e x p re s s my deep a p p r e c ia t io n t o th e S t e l l a Duncan M em orial Fund w hich p ro v id e d f i n a n c i a l a id d u rin g th e summer o f 1953 a s w e ll a s needed equipm ent; t o Dr* Ludwig G* Browman vdiose s u g g e s tio n s and c r i t i c i s m s p ro v ed i n v a lu a b le ; t o th e D epartm ent o f B otany w hich v e ry g r a c io u s ly a llo w e d u se o f t h e i r c o n tr o ll e d te m p e ra tu re and l i g h t room f o r th e e x p e rim e n t; and f i n a l l y t o my w ife who was e x tre m e ly h e lp f u l and d id most o f th e s t a t i s t i c a l a n a ly s e s. iii*»

5 TABLE OF COJiTEKTS Acknowledgement i l l L i s t o f T a b le s... t L i s t of F ig u re s... v I n tr o d u c tio n,..,.....,.,. * *.., # *. #.., *....,,.., 1 Review o f th e L i t e r a t u r e,*,..*,* **......, #. *.., 3 M a te r ia ls and M ethods., #.. *.. «,#..*,,.,* *».*.#. 11 R e s u its.* *.*,* «,.,.* # *,..#..* #..«.,,,* #,..,,* *, 17 D is c u s s io n....,. *.,,.....,.. *. 30 Summary...,....,.. #. # *.,.....,,.,....,.,, # #..., 36 C o n clu sio n s *.,.,..;# #.*..,,, L i t e r a t u r e C ite d, #,.. «*#.. *..,..... *....,,... j+0 - i v -

6 LIST OF TABLES T a b le Page 1. ELOOD SUGAR VALUES, lîüdividual RATS REGIME LG0D SUGAR VALUES, INDIVIDUAL RATS REGi^îE 2., ELOOD SUGAR VALUES, INDIVIDUAL RATS REGIME BLOOD SUGAR VALUES, INDIVIDUAL RATS REGXÏ-IE CO.VPARISOK OF DATA AGCO:aDIHQ TO REGIME AND TIAS OF DAT TAKEN * ELOOD SUGAR VALUES, L3TR0U3 CYCLE STAGE I, BLOOD SUGAR VALUES, K3TR0U3 CYCLE STAGE I I.... * 24 Ô. BLOOD SUGAR VALUES, ESTROUS CYCLE STAGS I I I.... 2$ 9* BLOOD SUGAR VALUES, ESTROUS CYCLE STAGS IV 25 10* BLOOD SUGAR VALUES, E3TR0U3 CYCLE STAGS V COMPARISON OF DATA ACCORDING TO ESTRCUS CYCLE S T A G E S *..,.*.*..* *...,..*...,*... 2? 1 2. COMPARlsav OF CO m i NED MEAN BLOOD SUGAR VALUES REGARDLESS OF TIME OF DAY TAKEN OR mcgi24b... *. 2& LIST OF FIGURES 1. ACTIVITY CYCLES OF 3 RATS, ONE EACH FROM Rn:G][M;S:3 1, 2,

7 INTRODUCTION The b lo o d s u g a r l e v e l i s o f fu n d a m e n ta l im p o rta n c e in th e s tu d y o f an a n im a l f o r many r e a s o n s. I t i s o f p rim ary im p o rta n c e i n th e p h y sio lo g y o f t h e o rg an ism b e c a u se i t i s th e *food* o f th e a n im a l on th e c e l l u l a r l e v e l. G lycém ie l e v e l s may a l s o be used a s an i n d i c a t o r o f t h e c o n d itio n o f th e a n im a l, and may be d ia g n o s tic o f a b n o rts ia litie a a s i n some hypoglycem ic and h y p e rg ly c e m ic c o n d it io n s. These l a t t e r c o n d itio n s may be p a r t i a l l y i n d i c a t i v e o f th e s t a t e o f many o f th e o rg a n s o f th e body; e s p e c i a l l y th e l i v e r, a n t e r i o r lo b e o f th e p i t u i t a r y, p a n c r e a tic i s l e t s o f Langerh a n s, a d r e n a l c o r te x, a d r e n a l m ed u lla and th e t h y r o i d, (C o ri, *40; F o lg ia ^ *47* G reene ^»39 I«ong ^ a i, *40; S o sk in e t a l - S o sk in e t al&»36 ). The q u e s tio n t h a t th e n a r i s e s i s, W iat a r e th e norm al v a lu e s f o r blood s u g a r, and w hat c a u s e s f l u c t u a t i o n s in th e s e v a lu e s? C o ri (*31^ g iv e s th e f i g u r e o f $2 mg p e r 100 cc a s th e t r u e v a lu e f o r b lo o d s u g a r f o r mixed v en o u s- a r t e r i a l b lo o d o f t h e r a t* However, t h i s f i g u r e i s n o t a c o n s t a n t, an d th e endogenous an d exogenous f o r c e s t h a t may in f lu e n c e i t a r e many. Among th e i n t r i n s i c f a c t o r s o f th e body t h a t in f lu e n c e b lo o d s u g a r, we know t h a t some o f th e 1

8 s t e r o i d s, in c lu d in g th e a d r e n a l c o r t i c a l e x t r a c t s and p o s s ib ly p r o g e s te ro n e may c a u se v a r i a t i o n s i n b lo o d s u g a r v a lu e s i n f e r r e t s and r a t s (G aunt ^ a i, *39} G reene a i, *39)# The p rim a ry i n t e r e s t i n t h i s i n v e s t i g a t i o n i s co n c ern ed w ith w h e th e r o r n o t a b lo o d s u g a r c y c le e x i s t s t h a t may be c o r r e l a t e d w ith th e e s tr o u s c y c le. T h is le a d s t o in s p e c t io n o f th e e s t r o u s - a c t i v i t y and m e ta b o lic c y c le s i n so f a r a s th e y a f f e c t b lo o d su g a r l e v e l s.

9 - 3- RSVIEW OF THE LITERATURE I t h a s been shown by many a u th o r s t h a t m u ltitu d e s o f c y c li c phenomena a r e e x i s t e n t i n a n im a ls. These in c lu d e I n g e s t io n o f fo o d ( R ic h te r, 27), a d r e n a l c o r te x a c t i v i t y (H a lb erg an d V is s c h e r, *52), l i v e r g ly co g en d e p o s itio n (B o u tw e ll ^ * W ; H ig g in s e t *32, 33; S o sk in e t *38), b a s a l m etab o lism (L e e, *20), d i u r n a l b lo o d su g a r (B o u tw e ll ^ *48; P i t t s, *43) a c t i v i t y (S lo n a k e r, *24; Wang, *23) and r e p r o d u c tiv e c y c le s (B landau and S o d e r- w a ll, *41; B o lin g e t a l. * 4 1 ). The many c y c lic v a r i a t i o n s a r e o f p rim a ry i n t e r e s t t o th o s e who w ould u n d e rs ta n d th e w hole organism ^ from th e p s y c h o lo g ic a l and p h y s io lo g ic a l p o in ts o f view. New i n fo rm a tio n i s b e in g so u g h t and a c c ru e d ab o u t th e rhythm s and t h e i r r a m i f i c a t i o n s, b u t th e end i s n o t y e t i n s i g h t. As an exam ple o f th e p o s s i b l e r a m i f i c a t i o n s, P e te rs o n (*47) even su g g e ste d t h a t "one m ight c o n s id e r th e p o s s i b i l i t y t h a t th e human group s e le c te d th e se v e n th day o f r e s t b ec au se o f an e x i s t i n g u n d e r ly in g b io c h e m ic a l rh y th m." Be t h a t as i t may c y c li c phenomena a r e o f fu n d a m e n ta l im p o rta n c e i n th e a n im a l. K leitm an (*49) s t a t e d t h a t, "a p h y s io lo g ic a l rhythm, s p e c i f i c a l l y th e d iu r n a l rhythm i s e s s e n t i a l l y a m e ta b o lic c y c le sy n c h ro n iz e d w ith th e e x t e r n a l p e r i o d i c i t y o f day

10 ip»» and n ig h t th ro u g h th e in f lu e n c e o f v a r i a t i o n s i n i l l u m i n a t i o n, te m p e ra tu re and o t h e r e n v iro n m e n ta l f a c t o r s on n e rv o u s and e n d o c rin e system s*" V a r i a t i o n s, up t o a p o i n t, may be in d u c e d i n th e s e rhythm s by la b o r a to r y m a n ip u la tio n o f such th in g s a s f e e d in g tim e s (B o u tw e ll e ^ a i, *48; H a lb e rg and V is s c h e r, *52; P i t t s, *43) and by a l t e r a t i o n s o f p e r io d s o f l i g h t and d a rk and o f te m p e ra tu re (Browman, *44). Normal b lo o d s u g a r, a s we know i t, i s p r im a r ily a f f e c t e d by d ig e s t i o n and a b s o r p tio n o f f o o d s t u f f s from th e g u t (B o u tw ell ^ a i, *48; P i t t s, *43) and th e dynam ic s u g a r- g ly co g en b a la n c e i ^ i c h i s l a r g e l y m a in ta in e d by th e l i v e r. The h o m e o sta sis o f b lo o d s u g a r i s, e v id e n tly, m a in ta in e d in l a r g e p a r t by th e dynam ic b a la n c e betw een i t and l i v e r g ly c o g e n a s (S o s k in, *40; S o sk in e t *38) d e te rm in e d by e x p e rim e n ts w hich m easured b lo o d s u g a r e n t e r in g and le a v in g t h e l i v e r u n d er norm al c o n d itio n s a s w e ll a s when s u g a r was b e in g added to th e b lo o d stream * The id e a o f a fu n d a m e n ta l h e p a tic r e g u la ti o n w ould a l s o seem t o b e s u p p o rte d by e x p e rim e n ts in v o lv in g h y p o p h y se c to m iz e d -d e p a n c re a tiz e d (H oussay) a n im a ls w hich have been m a in ta in e d f o r many w eeks w ith o u t i n s u l i n (S o sk in ^ j i, *36). M uscle g ly c o g e n n o rm ally p la y s a r e l a t i v e l y i n s i g n i f i c a n t r o l e i n m a in ta in in g glycém ie l e v e l s b ec au se i t i s in c a p a b le o f s u f f i c i e n t l y r a p id conv e r s io n t o g lu c o se (B ollm an ^ *2$). As S o sk in (*41)

11 rem arks» may t h e r e f o r e be s t a t e d a s a x io m a tic t h a t th e b lo o d s u g a r l e v e l r e p r e s e n ts a dynam ic b a la n c e betw een th e r a t e a t w hich b lo o d s u g a r i s e n t e r in g th e b lo o d stre a m from th e l i v e r and from an exogenous s o u rc e and th e r a t e a t w hich i t i s b e in g rem oved from th e b lo o d by th e t i s s u e s o f th e bo d y,* The l i v e r g ly co g en o f r a t s shows a q u a n t i t a t i v e» d i u r n a l, c y c lic v a r i a t i o n (H ig g in s ^ a.» *33)» w hich may be m o d ifie d by ch an g in g th e f e e d in g h a b i t s o f th e a n im a ls (B o u tw e ll ^ *40). C hanging o f th e norm al f e e d in g h o u rs, w hich o c c u r from 6 P.M. t o 12 m id n ig h t, t o th e m orning h o u rs c a u sed a r e v e r s a l o f th e l i v e r g ly co g en c y c le. The low o c c u rs h o u rs a f t e r f e e d in g i n b o th c a s e s (H ig g in s e t a l, *32; *33)* I t h a s been fo u n d t h a t b lo o d s u g a r a l s o e x h i b i t s a 24 h o u r c y c le (B o u tw ell e t a l *4B; P i t t s, *43)» P i t t s made noonm id n ig h t b lood s u g a r d e te r m in a tio n s on r a t s fe d ad l ib it u m, and fo u n d t h a t th e h ig h e s t b lo o d s u g a r r e a d in g s o ccu red a t m id n ig h t^ p resu m ab ly b ecau se o f th e f e e d in g h a b i t s o f r a t s u n d e r norom l c o lo n y c o n d i ti o n s. He a l s o d is c o v e re d t h a t a n im a ls t r a i n e d t o f e e d i n th e m orning h o u rs showed a r e v e r s a l o f th e b lo o d s u g a r c u rv e, ev en th o u g h th e y r e t a i n e d th e same 24 h o u r a c t i v i t y d i s t r i b u t i o n p a t t e r n a s a n im a ls a llo w e d t o fe e d n o rm ally * I t sh o u ld n o t, how ever, be assum ed from th e p re c e d in g d is c u s s io n t h a t th e h o m e o s ta tis m a in ta in e d by th e l i v e r i s

12 t h e o n ly f a c t o r to be reck o n ed w ith i n th e i n v e s t i g a t i o n s o f b lo o d su g a rs* A lso to be c o n s id e re d a r e th e a c t i o n o f th e p a n c r e a tic i s l e t s o f L a n g e rh a n s, th e a d r e n a l m e d u lla, th e a d r e n a l c o r te x, th e a n t e r i o r lo b e o f th e h y p o p h y sis, a s w e ll a s th e fu n d a m e n ta l enzyme sy stem s d is c u s s e d by C o ri (*40)* T here i s s t i l l u n c e r t a i n ty a s t o th e p r e c i s e f u n c tio n o f th e e n d o c rin e s in norm al m e ta b o lism, b u t i t i s b e lie v e d t h a t th e y a r e seco n d ary to th e l i v e r. L ik e w ise th e p o s s i* o f in f lu e n c e by o rg a n s o th e r th a n th o s e g e n e r a lly a c c e p te d, sh o u ld n o t be o v erlooked* The o v a ria n s e c r e t i o n s, f o r i n s t a n c e, may p la y some p a r t f o r i t h a s been shown (G aunt e t a l. *39» G reene ^ *39) t h a t p ro g e s te ro n e may have some * c o rtin * l i k e e f f e c ts * We m ig h t, h ere^ d i v e r t o u r a t t e n t i o n fro m b lo o d s u g a r and t u r n to th e o t h e r phase o f th e p h y s io lo g y o f th e an im al w hich I n t e r e s t s u s i n t h i s p a p e r; nam ely, th e r e p r o d u c tiv e cy cle* The re p ro d u c tiv e c y c le o f a n im a ls and t h e many changes w hich accompany i t, have b ee n o f i n t e r e s t t o many z o o lo g is ts * T h ere a r e b o th e x t e r n a l and i n t e r n a l d i f f e r e n c e s among th e v a r io u s s p e c ie s * Those su ch a s n e s t i n g b e h a v io r i n b ir d s and In c re a s e d a c t i v i t y o f la b o r a to r y r o d e n ts in e a t r u s a r e e a s i l y seen* The i n t e r n a l ch an g es o f w hich th e s e a r e th e m a n if e s ta tio n s a r e n o t so e a s i l y observed* S to c k a rd and P a p in ic a la o u (*17) d e v is e d a v a g in a l sm ear te c h n iq u e f o r

13 - 7 - d e te r m in in g t h e s ta g e o f th e e s t r o u s c y c le i n g u in e a p ig s, and Long and Evans (*22} a p p lie d t h i s i n t h e i r c l a s s i c work t o th e e s t r o u s c y c le o f r a t s. The r a t h a s p ro v ed to b e, e x c e p t f o r th e p e r s i s t a n c e o f th e c o rp o ra l u t e a th ro u g h s e v e r a l c y c le s, an e x c e l l e n t la b o r a to r y s u b je c t f o r th e stu d y o f s e x u a l and a s s o c i a te d phenomena s in c e i t s e s t r o u s c y c le i s o f r e l a t i v e l y s h o r t d u ra tio n * The e s tr o u s c y c le o f r a t s a s i n d i c a t e d by v a g in a l sm ears i s d e s c r ib e d a s p a s s in g th ro u g h f i v e d i f f e r e n t s ta g e s by Long and Evans (*22)* S ta g e I o r p r o e s t r o u s, i s c h a r a c t e r i s e d by sm all round e p i t h e l i a l c e l l s o f u n ifo rm s i z e and ap p e aran c e* The sm ear o f s ta g e I I o r e s t r u s i s fo u n d to c o n ta in la rg e ^ t h i n, t r a n s p a r e n t, n o n -n u c le a te d s c a le l i k e elem en ts* T h is i s th e p i c t u r e fo u n d a t th e tim e c o i t u s i s u s u a ll y p e r m itte d by t h e fem ale* The d u r a tio n o f t h i s s ta g s i s a p p ro x im a te ly 12 h o u rs w hich i s somewhat lo n g e r th a n th e tim e u s u a lly a t t r i b u t e d t o s ta g e X* S ta g e I I I, w hich ta k e s from h o u rs, i s n o t r e a d i l y d is t i n g u i s h a b l e from s ta g e XI* I t i s an e x a g g e ra tio n o f th e p re c e d in g s ta g e w ith s h e e ts o f c o r n i f ie d elem en ts^ and i s th e s ta g e in w hich o v u la tio n u s u a lly o ccu rs* A v a g in a l sm ear i n th e n e x t s i x h o u rs would be fo u n d to c o n ta in le u c o c y te s and rem n an ts o f c e l l s fro m XX - t h i s i s s ta g e XV o r m etestrum * The m ajo r p o r t io n o f th e c y c le h o u rs - i s ta k e n up by th e d i o e s t r o u s i n t e r v a l * o r s ta g e V* I t i s c h a r a c t e r iz e d by

14 ^a» le u c o c y te s and e m a il i r r e g u l a r l y shaped f r e e e p i t h e l i a l c e l l s c o n ta in e d i n t h i n s t r i n g y mucus* A cco rd in g t o Long and Evans ( 22) o v u la tio n o c c u rs a b o u t 21 h o u rs a f t e r th e f i r s t c o r n i f i e d c e l l s o c c u r, o r a s o th e r a u th o r s (B o lin g e t a l. 41) d e s c r ib e i t, o v u la tio n o c c u rs 10 h o u rs a f t e r th e s t a r t o f h e a t o r s e x u a l r e c e p t i v it y * A f te r o v u la tio n, c o rp o ra l u t e a form a t th e s i t e o f o v u la tio n, th e f u n c tio n a l l i f e o f w hich may be e x te n d e d by p reg n an cy o r pseudopregnancy. We have now a r r i v e d a t th e p o in t w here we may w e ll asks l a t h e r e any i n d i c a t i o n o f a p o s s i b le c o n n e c tio n betw een th e e s tr o u s c y c le an d b lo o d su g ar? T here w ould seem t o be i n t h a t G reene and h i s c o -w o rk e rs { 39) showed t h a t p ro g e s te r o n e, a s e c r e t i o n o f th e c o rp u s lu teu m o f t h e o v a ry, i s c o r t i n (a d r e n a l c o r t e x ) - l i k e i n t h a t i t w i l l m a in ta in l i f e and w e ig h t g a in i n a d re n a le c to m is e d r a t s. Gaunt e t (*39) r e p o r te d t h a t c o r t i c a l e x t r a c t s and p ro g e s te ro n e b o th e le v a te d l i v e r g ly co g en and b lo o d su g a r v a lu e s i n th e f e r r e t. T h is would seem t o le a v e room f o r s p e c u la tio n on t h e p o s s i b i l i t y o f o v a ria n i n f lu e n c e on b lo o d sugar* They a p p lie d s i m i l a r e x p e rim e n ta l p ro c e d u re s t o r a t s. They a ls o fo u n d t h a t c o r t i c a l e x t r a c t s e l i c i t e d s i m i l a r re s p o n s e s, b u t th e in f lu e n c e o f p r o g e s te r o n e, i f an y, was e x tre m e ly s l i g h t. Some more in fo rm a tio n a b o u t th e p o s s i b i l i t i e s o f a c o n n e c tio n betw een th e e s tr o u s c y c le and m e ta b o lic p ro c e s s e s was p ro v id e d by Lee ( 2Ô), who made a t o t a l o f 2Ù2 b a s a l m e ta b o lic r a t e d e te r m in a tio n s on 9 fe m a le r a t s d u rin g a l l

15 A tag e8 o f th e e s tr o u s cy c le * I n a l l o f th e a n im a ls an In c r e a s e d b a s a l h e a t p ro d u c tio n was o b se rv e d d u rin g th e l a s t 10 h o u rs o f s ta g e 7 and th e f i r s t s i x h o u rs o f s ta g e X«A d i f f e r e n c e o f aro u n d 135^ above t h a t o f s ta g e s I I, I I I and 17 was fo u n d. Lee s a id t h a t t h e m ain e v e n t c o in c id in g w ith th e r i s e i n b a s a l h e a t p ro d u c tio n was a r a t h e r p r e c i p it o u s d e g e n e ra tio n o f th e co rp u s lu teu m, and he co n clu d ed t h a t **the c o rp u s lu teu m may have a m e ta b o lic s p a r in g o r a n a b o lic f u n c tio n, and upon rem oval o f i t s i n f lu e n c e a p e r io d o f in c r e a s e d k a t a b o l i c a c t i v i t y b e g in s." The p o s s i b i l i t y o f a c o n n e c tio n betw een o v a r ia n s e c r e t i o n, o f w hich th e e s t r o u s c y c le i s a m a n if e s ta tio n, was in c r e a s e d hy th e work o f F o lg ia ^ S c h u s te r and R odriguez (*47) w hich showed sex d i f f e r e n c e s i n th e re s p o n s e s o f r a t s to a 95^ p a n c re a te c to m y. T h e ir fem ale r a t s became d i a b e t i c l e s s f r e q u e n tl y and e x h ib ite d a h ig h e r r a t e o f s u r v i v a l. They a l s o n o te d t h a t c a s t r a t i o n i n m ales had an a m e lio r a tin g e f f e c t* w h ile in fe m a le s, c a s t r a t i o n s e n s i t i z e d th e a n im a ls t o d i a b e t e s. L a te r (Lew is ^ *50) i t was shown t h a t e s tr o g e n ic s u b s ta n c e s d e c re a s e th e in c id e n c e o f d i a b e t e s, w h ile a n d ro g e n ic o n es in c r e a s e them. We may p u rsu e th e problem a t hand - th e q u e s tio n o f a c o r r e l a t i o n betw een th e e s t r o u s c y c le and b lo o d su g a r - s t i l l f u r t h e r by assum ing, h ig h ly s u p p o s itio n a l a t t h i s s ta g e, t h a t a p o s s i b i l i t y o f some o v a ria n i n f lu e n c e on b lo o d s u g a r

16 10- do es e x i s t. The q u e s tio n w hich would th e n come t o th e f o r e I s : Does a p e r io d o f change i n s e c r e t i o n o f s u b s ta n c e s by th e o v ary e x i s t w hich c o u ld c o n c e iv a b ly c a u se a change i n b lo o d su g ar? Âstwood (*39)» u s in g u t e r i n e changes a s i n d i c a t o r s o f o v a r ia n ch an g e, to o k th e r e s u l t s o f some o f h i s e x p e rim e n ta l work t o mean t h a t e s tr o g e n a c t s unopposed d u rin g a b r i e f p e r io d j u s t p r i o r t o v a g in a l c o r n i f i c a t i o n. He a ls o s t a t e d t h a t th e co rp u s lu teu m hormone i s r e le a s e d from th e f o l l i c l e s d u rin g t h e i r p r e - o v u la to r y s w e llin g, and c e a s e s to be p ro d u ced a t a p p ro x im a te ly th e tim e o f o v u la tio n. T h is, i n I t s e l f, w ould seem t o p ro v id e su p p o rt f o r th e t h e s i s t h a t a r a t h e r r a d i c a l change i n o v a ria n s e c r e t i o n does o c c u r. B o lin g and B landau*s (*39) r e s u l t s c o n t r a d ic t t h i s f o r t h e i r r e s u l t s showed t h a t e s t r u s in d u ced i n a spayed fem ale r a t by th e s y n e r g i s t i c a c t i o n o f e s tr o g e n and p ro g e s te ro n e more n e a r ly ap p ro x im ated t h a t e x h ib ite d by a norm al fe m a le th a n when e s tr o g e n a lo n e was u s e d. The dom inance o f e s tro g e n a t some tim e s and p ro g e s te ro n e a t o th e r s i n th e e s t r o u s c y c le i s g e n e r a lly a c c e p te d. The am ount o f horm ones p r e s e n t i s p ro b a b ly a r e l a t i v e th in g w ith some o f each b e in g p r e s e n t a l l th e tim e (A stw ood, *39» B o lin g and B landau *39; Hisaw e t a l. *34). Up t o d a te no c l e a r c u t r e l a t i o n s h i p betw een th e e s t r o u s c y c le and b lo o d s u g a r i n th e r a t h a s been r e p o r te d.

17 - 11- M a te r ia ls and M ethods I n t h i s e x p e rim e n t, th e o b je c t o f w hich was t o se e w h e th e r o r n o t a c o r r e l a t i o n e x i s t s betw een g ly cém ie l e v e l s and th e e s tr o u s c y c le i n r a t s, f o u r d i f f e r e n t reg im es w ere s e t up t o f a c i l i t a t e th e s tu d y. They w ere: 1. L ig h t 0 A.M. t o 8 P.M., d a rk 8 P.M. t o 8 A.M.; r a t s a llo w e d t o fe e d l i b i t u m. 2. L ig h t 8 A.M. t o 8 P.M., d a rk 8 P.M. t o 8 A.M.; r a t s a llo w e d t o fe e d from 8 A.M. t o 1 P.M. o n ly. 3* L ig h t 8 A.M. t o 8 P.M., d a rk 8 P.M. t o 8 A.M.; oophorectoüsised a n im a ls a llo w e d t o fe e d ad l i b l t i m. i. Dark 8 A.M. t o 8 P.M., l i g h t 8 P.M. t o 8 A.M.; r a t s a llo w e d t o fe e d W l i b i t u m. The e x p e r im e n ta l p ro c e d u re, i n a l l c a s e s, a llo w e d f o r f r e e a c c e s s t o w a te r. I n d i v i d u a l c a g e s w ere p ro v id e d f o r a l l r a t s. The a n im a ls w ere fe d B n o. 21 {Browman, *44) t o w hich a m in e ra l supplem ent was ad d ed. L e ttu c e was fe d two t o t h r e e tim e s a w eek; i n th e c a s e o f a n im a ls i n regim e 2 th e l e t t u c e was l e f t i n th e ca g es from 8 A.M. to 1 P.M. o n ly. The p e rio d th ro u g h which th is e x p e rim e n t was c a r r i e d on e x te n d e d from May 1953 t o November T h is was n e c e s s i t a t e d by a lim ite d num ber o f a c t i v i t y c a g e s. I n t h i s tim e a t o t a l o f 56 n u llip a rc -u s fe m a le r a t s o f a n e a r ly homogenous g e n e t i c a l c o m p o sitio n w ere u s e d. t h e i r f o r ty - s e c o n d in b re d g e n e r a tio n. The a n im a ls w ere i n The s e l e c t i o n o f r a t s

18 12"" was made on th e b a s i s o f age# w e ig h t and o v e r a l l c o n d itio n # The r a t s u se d w ere a p p ro x im a te ly 90 days o ld - p lu s o r m inus 10 d a y s, w hich f a l l s w e ll w ith in th e two month ra n g e s e t up by S h ir le y (*28) f o r r e l a t i v e hom ogenity o f a c t i v i t y. The r a t s w ere s e l e c te d f o r t h e g ro u p s so t h a t w here p o s s ib le l i t t e r m ates w ere p u t i n t o more th a n one g ro u p, o th e r w is e, no c o n s c io u s s e l e c t i o n was e x e r c is e d i n p la c in g them in one group o r a n o th e r. S ix te e n a n im a ls co m p rised th e e x p e rim e n ta l group o f regim e 2, w h ile tw e n ty * fo u r w ere i n group number 1, The a n im a ls i n th e l a t t e r group se rv e d a tw o fo ld f u n c tio n i n t h a t th e y w ere c o n t r o l s f o r a c t i v i t y and w e ig h t g a in, w h ile a t th e same tim e s e r v in g as experi-* m e n ta ls f o r b lo o d sugar# Group 3 and 4 each c o n ta in e d e ig h t an im als# F o llo w in g th e p ro c e d u re o f S h ir le y (*28) th e r a t s w ere a l l a llo w e d a 1$ day p re -e x p e r im e n ta l p e r io d i n which to become a c c lim a tis e d t o t h e i n d i v i d u a l w heel ty p e r e c o rd in g e x e r c is e cages* I n tr o d u c tio n t o m o d ifie d fe e d in g reg im es (Group 2 o n ly ) t o f r e q u e n t h a n d lin g, and t o sm ear ta k in g was done i n t h i s 15 day p e rio d * The e s t r o u s c y c le, a s i n d i c a t e d by v a g in a l sm ears^ was re c o rd e d f o r i n d i v id u a l r a t s, b u t p ro b a b ly th e m ost im p o rta n t f u n c tio n o f t h i s p e rio d was t o f a m i l i a r i z e th e a n im a ls w ith th e h a n d le r# The a n im a ls became q u i t e tam e and w ould clim b o n to th e hand by th e end o f th e o r i e n t a t i o n p e rio d # The e x p e rim e n to r d id a l l cage

19 - 13- c le a n in g, f e e d in g and w a te r in g d u rin g th e 15 day a c c l i m a t i - statio n p e r io d and 30 day e x p e rim e n ta l p e rio d * The e ig h t a n im a ls u sed i n e x p e rim e n ta l regim e 3 w ere b i l a t e r a l l y ov a r ié e torn!zed a f t e r b e in g a n e s th e ti z e d by sodium p e n t o b a r b i t a l i n j e c t e d i n t r a - p e r i t o n e a l l y * The d o r s a l a p p ro a c h, which n e c e s s i t a t e d two i n c i s i o n s, was used* The I n c i s i o n s, how ever, w ere q u it e s m a ll and h e a lin g was ra p id * The a n im a ls w ere housed in two d i f f e r e n t rooms* Those i n g ro u p s 1, 2 and 3 w ere i s o l a t e d i n th e c o n tr o l room in a c o rn e r o f th e greenhouse* T h is room i s l i n e d w ith f i b e r b o a rd, h a s a c o n c re te f l o o r, and a wooden door* T hree benches^ s ta n d in g a p p ro x im a te ly t h r e e f e e t o f f th e f l o o r, c o m p le te ly l i n e t h r e e w a lls* The a c t i v i t y ca g es w ere p la c e d on th e s e * Two f e e t above th e b en ch es a r e f l u o r e s c e n t l i g h t s g iv in g r e l a t i v e l y even i l lu m i n a t i o n on t h e benches* They a r e a u to m a tic a lly c o n tr o lle d by a T e le c h ro n tim e sw itch * T em p eratu re c o n tr o l was m a in ta in e d by a m an u ally o p e r a te d th e r m o s ta t, w hich h e ld th e te m p e ra tu re a t 75^F - 1 F* R e la tiv e h u m id ity was n o t c o n t r o l l e d, n o r w ere th e sounds n o rm a lly a s s o c ia te d w ith a c t i v i t i e s i n th e greenhouse* The a n im a ls o f group 4 w ere k e p t i n in d iv id u a l cag es i n dead s to r a g e room* T h is room i s a c c e s s i b l e o n ly by a la d d e r fro m t h e stockroom o f th e Zoology D epartm ent* te m p e ra tu re h e r e i s q u ite c o n s ta n t b u t u n c o n tro lle d * The The

20 -li» - l i g h t s in t h i s room a r e m anually o p e ra te d # These a n im a ls w ere exposed to l i g h t once e v e ry t h r e e d ay s d u rin g th e d a rk p e r io d f o r a b o u t 5 m in u te s d u rin g th e tim e when th e y had t o be rem oved from t h i s room t o take b lo o d sam p les. D u rin g th e e x p e rim e n ta l p e r io d, b lo o d su g a rs w ere ta k e n by t a i l c u t t i n g once e v e ry t h r e e days* T h is a llo w e d tim e f o r t h e r a t s t o r e tu r n to norm al p h y s io lo g ic a l c o n d itio n and t o a l l a y f e a r o f th e i n v e s t i g a t o r in d u c e d by th e t a l l c u t t i n g (H a lb erg and V is s c h e r, 52). B lood s u g a r d e te r m in a tio n s w ere made a t Ô A.14., 1 P.M. and $ P.M. I f a p a r t i c u l a r r a t was sam pled a t Ô A.M. on one d a y th e n e x t sam ple w ould be ta k e n a t ê P.M. t h r e e days l a t e r, and th e n a t 1 P.M. a fte r an a d d i t i o n a l t h r e e days. A v a g in a l sm ear o f each r a t was made d a i l y, i n th e e v e n in g u n le s s a b lo o d s u g a r sam ple was made t h a t day, i n w hich c a s e th e sm ear was made a t th e same tim e. The sm ears w ere o b ta in e d by in tr o d u c in g a m o iste n e d p l e d g e l e t o f c o tto n i n t o th e v ag in a o f th e a n im a l. The c e l l s w hich ad h ered t o th e c o tto n w ere ru b b ed o f f on a c le a n g la s s s l i d e and exam ined. Long and Evans (*22) c r i t e r i a w ere u sed to dete rm in e th e s ta g e o f th e e s tr o u s cy cle* O ophorectom ized a n im a ls a l s o had v a g in a l sm ears ta k e n in o r d e r to d u p l ic a te e x p e rim e n ta l c o n d itio n s. A nim als from w hich sam ples f o r b lo o d s u g a rs w ere to be ta k e n w ere a llo w e d t o e n t e r a s p e c i a l l y c o n s tr u c te d r e s t r a i n e r.

21 - 15- T h is c o n s is te d o f a b lo c k o f wood Ô in c h e s lo n g and in c h e s w ide t o td iicb a r e c ta n g u la r p ie c e o f s t i f f w ire mesh had been e t t - c h e d t o form a cage open a t b o th ends th e a p p ro x im a te le n g th and d ia m e te r o f th e a n im a l s body* The t a l l was th e n p la c e d and h e ld i n a b e a k e r o f w a te r a t 35^C f o r 30 seconds* The t i p o f th e t a i l ws.s th e n d r ie d and am p u tated and th e b lo o d c o l l e c t e d i n a sm a ll p a r a f f i n l i n e d d ish * A Kahn p i p e t t e was u se d to draw up 0.1 cc o f t h i s b lo o d w hich w as th e n d e l iv e r e d i n t o a sm a ll f l a s k c o n ta in in g 10 cc o f a d i l u t e t u n g e t i c a c id s o l u t i o n. The p i p p t te was f lu s h e d w ith t h i s s o l u t i o n, a f te r w hich th e f l a s k s c o n te n ts w ere th o ro u g h ly m ixed and th e n f i l t e r e d. A ll d e te r m in a tio n s were made i n th e e v e n in g o f th e day i n w hich sam pling to o k p la c e. I n th e i n t e r v a l betw een th e sam p lin g and th e a c tu a l d e te r m in a tio n s th e sam ples w ere s t o r e d on th e s h e lv e s o f a h o u se h o ld ty p e r e f r i g e r a t o r. The F olin-m alm ros b lo o d su g a r m ethod {*33) was u se d in th e d e te r m in a tio n s. T h is c o lo r m e tr ic m icro-m ethod depends on th e feet thét when a g lu c o s e s o l u t io n i s h e a te d w ith an a l k a l i n e f e r r l c y a n i d e s o l u t i o n, th e f e r r i c y a n i d e i s re d u c e d t o f e r r o c y a n id e. The f e r r o c y a n id e w i l l r e a c t w ith a f e r r i c ir o n s o l u t io n t o p ro d u ce a b lu e c o lo r w hich i s m easu rab le i n a c o lo r im e te r. Two d i f f e r e n t c o lo r im e te r s were u sed in th e s tu d y, Cne was a Baush and lomb Dubosoq type, th e o th e r a Dausch and Lomb m onochrom atic, d i r e c t r e a d in g, s i n g le beam o n e. When th e sw itc h w as made from one ty p e o f c o lo r im e te r

22 t o a n o th e r b lo o d su g a ra w ere ru n w ith b o th in s tr u m e n ts and i t was fo u n d t h a t th e y gave s i m i l a r r e a d in g s. The s ta n d a r d g lu c o s e s o l u t i o n, a g a in s t w hich th e unknown was r e a d, was p re p a re d f r e s h e v e ry w eek. I t was m a in ta in e d in a s t e r i l e f l a s ^ in a r e f r i g e r a t o r. S am pling i s th e m ost c r i t i c a l p o in t i n th e whole e x p e rim e n t. The sam ple m ust be a c q u ir e d r a p i d l y, in l e s s th a n t h r e e m in u te s, o r th e b lo o d becom es h y p e r g ly c e m ic. C l o tt in g may a l s o o c c u r i n t h e c o l l e c t i n g d is h i f th e b lo o d flo w i s slo w. A ll b lo o d s u g a r sam p les w hich r e q u ir e d more th a n t h r e e m in u te s o f b le e d in g w ere d is c a r d e d b ec au se o f th e h y p e rg ly c e m ic f a c t o r. S t a t i s t i c a l s i g n i f i c a n c e th ro u g h o u t t h i s p a p e r was b ase d on th e ^ t e s t a s d e s c rib e d i n S nedecor (^40). T h is t e s t i s d e sig n e d s p e c i f i c a l l y f o r t e s t i n g th e s ig n if ic a n c e o f d i f f e r e n c e s betw een m eans. I f t h e p ro b a b i l i t y t h a t th e d i f f e r e n c e was due t o chance a lo n e was g r e a t e r th a n 5^ i t was assum ed t h a t t h e r e was no d i f f e r e n c e.

23 R e s u lts The p r o b a b i l i t y i s v e ry h ig h t h a t a c o r r e l a t i o n does e x i s t betw een t h e e s t r o u s - a c t i v i t y c y c le and f l u c t u a t i o n s i n mean b lo o d s u g a r v a lu e s. The blood s u g a r r e a d in g s from th e 4Ô r a t s on re g im e s 1, 2 and 4 w ere u sed i n t h i s ph ase o f th e s tu d y. Combined e s t r o u s c y c le s ta g e s I and I I (mean b lo o d su g a r o f 104*5 mg when compared w ith com bined e s t r o u s c y c le s ta g e s XII, IV and V (mean b lo o d s u g a r o f mg %) gave a t v a lu e o f T here w ere 332d e g re e s o f freedom i n t h i s co m p ariso n. F o r 300 d e g re e s o f freedom th e ^ v a lu e a t th e 1% l e v e l i s ; s in c e th e sam ple v a lu e f a r ex ceed s even th e 1% l e v e l we may assum e a s i g n i f i c a n t d i f f e r e n c e betw een th e grouped s e l e c te d e a tr u s sta g e s * A s t a t i s t i c a l s i g n i f i c a n c e, even a t th e 5% l e v e l, does n o t exist* when in d i v id u a l e s tr o u s c y c le s ta g e s a r e com pared one w ith th e o th e r* Summaries o f th e d a t a u se d i n com paring th e b lo o d s u g a rs and e s tr o u s c y c le s ta g e s may be seen i n T a b le s 11 and 12* A com parison o f t h e mean b lo o d s u g a r v a lu e s was made f o r a l l r a t s on re g im es 1,2,3 and 4 by th e tim e o f day sam p lin g o c c u re d, and by th e p a r t i c u l a r regim e (T ab le 5)* The raw d a ta f o r t h i s p h ase o f th e s tu d y may be fo u n d i n T a b le s 1-4. The tw e n ty -f o u r a n im a ls on reg im e 1, w hich

24 18 w ere f e d l i b i t u m, d id n o t show s i g n i f i c a n t d i f f e r e n c e s i n mean b lo o d s u g a r v a lu e s when th e s e v a lu e s w ere compared by th e tim e o f day th e sam ple was ta k e n. The mean g ly cém ie v a lu e s f o r th e 8 A.M., 1 P.M. and 8 P.M. sam p lin g p e r io d s w ere 103*7 mg ÿ* mg % and 104 mg % r e s p e c t i v e l y. I n regim e 2, how ever, a s t a t i s t i c a l s i g n if ic a n c e b ase d on th e tim e o f sam p lin g p e r io d s f o r b lo o d s u g a rs was o b ta in e d. The 8 A.M. re a d in g s (102 mg %} when com pared w ith 8 P.M. r e a d in g s (106 mg %) w ith 69 d e g re e s o f freedom gave a X v a lu e o f The ^ v a lu e f o r 70 d e g re e s o f freedom a t th e 5^ l e v e l i s , w h ile th e ^ v a lu e a t th e 1% l e v e l i s The 1 P.M. re a d in g s (103 mg when com pared w ith t h e 8 P.M. v a lu e w ith 75 d e g re e s o f freedom g iv e s a ^ v a lu e o f F o r 80 d e g re e s o f freedom th e t v a lu e s a t th e and 1% l e v e l s a r e and r e s p e c tiv e ly * A s i g n i f i c a n t d i f f e r e n c e betw een th e b lo o d s u g a r means b ased on fe e d in g tim e s i s q u i t e p ro b a b le in b o th th e s e c a s e s, t h a t i s, 8 A.M.-8 P.M. and 1 P.M.-8 P.M. A d i f f e r e n c e i s n o t e x h ib ite d betw een 8 A.M. and 1 P.M. mean glycém ie l e v e l s. The b lo o d s u g a rs o f th e 8 o o p h o recto m ized r a t s on regim e 3 d id n o t v a ry s i g n i f i c a n t l y w ith th e tim e o f th e sam p lin g p e r io d. Mean b lo o d s u g a rs o f mg mg fo and mg ^ w ere o b ta in e d a t 8 A.M., 1 P.M. and 8 P.M. r e s p e c t i v e l y.

25 - 19- The e s tr o u s c y c le a s d e te rm in e d by v a g in a l sm ears and a c t i v i t y r e c o r d s on a l l I n t a c t a n im a ls was fo u n d to be com pleted I n t o 5 days# T h at I s, e s t r u s o cc u red e v e ry Uh t o 5 days a t th e tim e o f maximum sp o n ta n e o u s a c t i v i t y # Graph 1# A t y p i c a l a c t i v i t y c y c le may be se e n in

26 20** ato S I «6: 30 gi A % % «n 315 %! tnm % 2^8 f* f# «8 00 CNOO _ Oj m m S S î:3 «Mg. NQ X>% s? S3 ws IN O On ON O M s s l 8 S 8 : M»H#4 m o m s s s o o r-» W w m r4 O <?V 93»18 8 CN. 3 <yv o o ON a VL ms ic s g: NO WN r~ f i m m % s % vr OC s4» H t t JS- 3 m 3 g MN 3 M s g CMm w «4 r4 o o o 4 *4 *4 r-i H S:^ m m x> m o o o o p4 *4 r4 f4 O»4 BN. «4 r4 O O «4 r4 (4 *4 tr r* IN 3 r r ff' ^ s s rhtflt a CM #4 S CM<4 m P o o o *4 «4 f4 5 8^3 #4 *4 «4 S 3 s &R f4 #4 r4 (Hi r M NO S 3 G & fh s i % i4 r4 % co m as o «H #4 #4 A, <N «Noo CM ^ Sn«> ON O O m e <4 «4 r4 r- m m g o j4 f4 WN C4 VO «y «4 O *4 4 _ * CVJ K & r4 ç4 g m m ON g o o P #4 #4 f4 Hf «MVONâ O O «4 O fc H* H# H* #4 #4 m o <si m s s s s «4 #4 S;@. ^ CNi OD %Ti Vf% CVJ 8 O' Cn. o r4 333 NO CM 33 CO^ CM i- i O #4 N- f*4g8 S»4»4 i4 8 4» * I4J* 3 ce IvC *M 0 «1 SJ I t3 v4 g S3 M I #Iciw O g <D.O Î I m ri I

27 -.21-8^ r~i W % «#t-4 >o M s> s> Ifl r 4 S» J» p4 VA«-4 Ch- O»-f O r4 r4 r4 a s i a g s s â?y <y vo o «-4 ih CM «y 3 M o \ f# p4 H ts- Oh r4 C» M O W M f4 #4 p4 fa ty r*4 r4 r 4 W o o o r-# #4 f4 O Oh O O O r 4 r4 th.4 O VACh. SO -a y4 f4 p4 «M «I a O ' a o p - S > V i N S m ON 33 & ç- Ch 0^0 0 c o f-i (-1 M N 0^ sss X fx, O ' 00 NO: $8 t-i \P 8; \o %n 33 ty 333 % CO 04 co ho Vh r4 SO OO W r4 O O f-4 r4 it4»*4 p4 OssO 'ASC r 4 O s f 4 C» 1^ r4 r4 (T>Os O r 4 f"t p4 S 1 % ë 0 m S' OhçO N fn r4 r4 (-4 0» ey «y j@- O CT' 83 m 3 <y CKth. (jmht W"^ ü ) O >h o O 1*4 f4 I S.» «y es. o so o o» t r4 W *"4 *-4 1 g Ty r \ o \ o o *-* vo &:g 1«g

28 - 22- TABLK 3 BLOOD SWAB TALÜJS, littlvidual BATS ÎÆÜIMB 8 A.K, Rat no ,, »S % * P.M Rat no I l l mg ^ P.M. Rat. n o , mg ^ TABLE 4 BLOOD SUGAR VALUES, INDIVIDUAL EATS M IME 4 8 A.M. Rat no I l l 108 mg ^ l.P_#.K_,..._ Rat no : _ mg # lo ^ 98 _ P.M. Eat no mg ^

29 - 23^ CO * 0 3 A» O # t*- o tnt 5 «I A * O D* «g W * M H» a R O # fh s «A rh VA r rh 1 ih K P o (Ao 5^8 00 moo \C v>v 5 s o v \ s c t 4 rh f m ev- R A s evrco vo 00» * * B m r H 8% o A VA rh o % a VO rh Ç n v O rh SO r * Jÿt vr, VTV ÎM», O V4 H% A W\ o en o CM O I V CM 1 ^ N * # # * -rt.af O o o o o o fh fh rh im rh v% v% r4 o r4 o thr4 o o fh o ym o O * o jÿo m cj m w vo fnvo o o o o o o rh * t H r-, rh rh c f \ % n rh N rh v o CC VO O O O O O O rh fh r«t rh r~! rh e r. o jj- <0 -sî' - -«CO <n vo vo vo 'n VO rhrh o o rhrhrhrh o o o o t s. (S. t s. U*% C h \T \ O O O O O O rh «H rh rh rh ph N m vr> j r «n^t o o rh rh V \ «n ^ o o # «n c v l SA CM en en -d- m o o o o rh rh rh rh VA (A evi *ej- CVJ O O O O ; 1, I o S g k-, l3î «4 O» o f z "A * sê se ' 03 B À Ai v4 H 00 rh g 1 o *» i t M I a s r 8 I V o ^ rh #H r 4 2 à RS' I sé I 2 li rh G V# w co «* * «*» ^ p4 OL, f k 4H co co rhco o %) A &1 o cil * f o «MW rha% -a a" % W 4» ^ - «5!î CO flj > r»t> Ov Ov Ov Ov Ov rh rh rh rh r"< rh rh rh rh rh rh rh ck (k q& oo GO 0 0 ÛO co 0 0 ^ <0 H t s c <5 v o <n 3 m «n c ' «* * >: X. 3t. X «* * * O r " 4 0 * # * ae 3E r * P r A l OO rh CO 0 0 rh CO I * %»!o e. r-f I H* ^. ^co «3 «' g «r. B % 3E rh * A CO CO rh #-% <as «K2 & rh «rh t «S3 _ O th O =SS» J & #H O 3 V» _ «Il #Ht 8 5 (b4 f r f4 OnCÏ^ ov ci CV- Ov hj Ov cî- 0\ flo ph rh «H 00 «Si IN* w rh N rh (VI * # -4-4 '# ae»» 3K «as: r ae # S 4 A* h3 Ar Ai Ah oo rh t h % m o. ^ B a; se A CO co rh CO gs M #» Vt i»h*<h B S3 _ U p i f Xi r-% * 0 «ta gg» Sll m vr\ m On VA CN rh rh rh rh rh «H rh rh rh rh rh ph A sa ça A A (A o v o v O v O n O n ON zy (A (M «vj» se r < Ai CO rh I t VA en VA CJ (Ni WCVJ as se i r %se i h3 Ai Ai Ai CO CO rh oo a s < * 5 r, a i f, : «H â ^ s, s. N-rT «ri rh z» «_ r4 h 3 I» & rh W,o o8 S«a 5 >5^ 5 3 -S a o A3 OO c o B *H rh S

30 24^ TAELS 6 BLOOD SDGAB VALUES, ESTBOÜS CYCLE STAGE I Bat «g ^ ? ^ * * Ba t _ , p 41 42, g ^ TABLE 7 BLOOD SWAB VALUî?S, ESTBOUS CYCLE STAGE II Rat fflg ^ * Bat MS * Bat mg ^ Dropped b ecau se o f h yp erglycem ia

31 T A 3 L B 8 ELO O D SUGAE V A L U E S, E S T E O n S G T C LB STAG S I I I Eat 1 2 3, IQ * p 21 22? , a g ft Eat n mg f TABLE 9 BLOOD SUGAE VALUB:S, ESTSOUS CYCLE STAGE IV Rat ,15 : I l l mg f Eat ?4 25? 6 2 7_ , mg f Eat Dropped because o f hyperglycem ia*

32 TABLE 10 BLOOD SU&AB VALUES, ESTBfJUS CYCLE STAGE T Rat n 12, mg ^ 160# Rat ? 16 1? «g ^ l6o* Eat mg 11^ io Rat ? mg SÊ m, Dropped hyperglycem ia W

33 T ijs L S 11 COMPAPJSOH OS m m ACCOKDim Ï 0 ESTBDUS CYCLE SmOB Setrou# ITuaber c y c le o f sta g e Sammies X 35 XX 89 I* XIX X* IT I* V II* XII* XX* IT* Animal# Bang# Median Mean 1* * lo é * Mean D iff S.D, S.E. s i «0.1 i* , , Bo Bo Bo Bo Bo II* T* Bo^ III* IT* Bo III* T* Bo IT* T* , Bo # D ata rep eat#** 1 Approaching eig a lflc a n e e *

34 - 2 &. II os N» O %# %n o\ k i 0)1 v \ o «V M # tn o CNJ A ««0 \0 SiSï P» * ^ v\ ÇN.NONO ON N NOr>o é ^ NO NO I "VL I m It) r-* NOO 4 v i (?<a3 NONT% o o *w PJ NO ON o IB mco CO «6 % f w V> ONQ f4 fwtnj SS3 OOCO^ dt- to»-4 rn m rn 1-4 o 1-4 o «t o rn On >-«> t**

35 F I GURE 1 ACTIVITY CYCLES OF THREE TYPICAL RATS ONE EACH FRO M REGIMES I, 2 AND 3 2. Teg/me 3 a s t r o u s cyc/e X a*>dl J L I I e s t r e a t c y c /e UI,TS 9n<i-'Z' \ ' / \ S. a 4 f & T f? f«",1, 3 fv ^ * /7 ft If JO 3/ j - / j f J» 3T 2Y hour firrro9f

36 D is c u s s io n I t can be se e n from th e r e s u l t s t h a t th e f i v e s ta g e s o f th e e s t r o u s c y c le w ere d iv id e d i n t o two groups} nam ely, one group in c lu d in g th e Long-Evans ( 2 2 ) s ta g e s I and I I, and t h e o t h e r in c lu d in g t h e s ta g e s I I I, XV and V# The re a s o n s f o r com bining th e s ta g e s w ere th e r a t h e r o b v io u s s i m i l a r i t i e s o f th e means w ith in th e tw o g ro u p s and th e f a c t t h a t a lth o u g h d if f e r e n c e s w ere o b s e rv a b le betw een th e e s t r o u s c y c le s t a g e s, th e y w ere o f to o s m a ll a m agnitude t o e x h i b i t s ig n if ic a n c e i n th e l im ite d num ber o f sam p les o b ta in e d i n th e e x p e rim e n ta l p e r io d. The d i v i s i o n i n t o two g ro u p s i s n o t n e c e s s a r i l y an a r b i t r a r y n o r a r t i f i c i a l one b ec au se we can s e e s i m i l a r i t i e s i n th e a c t i v i t y p a t t e r n a s w e ll a s i n mean b lo o d s u g a r v a lu e s. A c t i v i t y, which i s a m a n if e s ta tio n o f i n t e r n a l changes h a s b een shown by many a u th o r s ( R ic h te r, *27} S h i r l e y,»20; S lo n a k e r, *24; Wang, *23) and by th e a c t i v i t y g rap h (Graph X) t o be in ascen d an ce and a t i t s peak d u rin g s ta g e s I and I I and t o be d e c li n in g and a t i t s ebb in s ta g e s I I I, IV and V. C o r r e la te d w ith a c t i v i t y we f i n d in th e o v ary i t s e l f p r e p a r a tio n f o r o v u la tio n i n s ta g e s I and I I and o v u la to r y - p o s t- o v u la to r y changes i n s ta g e s I I I, IV and V (B o u tw ell ej^ *48; Hisaw e t *34; Long an d E v an s, * 2 2 ). In t h e u t e r u s we f i n d v a s c u la r en g o rg em en t, and m arked d i s t e n t i o n i n s ta g e s I and I I. I n s ta g e I I I th e u t e r i n e

37 31- f l u l d d is a p p e a r s and th e s t a t e o f d i s t e n t i o n i s r e p la c e d by one o f f l a c c i d n e s s. The l a t t e r c o n d itio n s a r e m aint a i n e d th ro u g h s ta g e s IV and V (Long and E v an s, * 2 2 ), I t i s e x tre m e ly i n t e r e s t i n g t o c o n s id e r th e b lo o d s u g a r v a lu e s f o r th e v a rio u s s t a g e s o f th e e s t r o u s c y c le w h ile k e e p in g in mind th e c o n c o m ita n t s e c r e to r y p h a se s o f th e o v a ry. The lo w e st mean g ly cém ie v a lu e (103*4 mg p e r c e n t) o ccu red d u rin g com bined s ta g e s I I I, IV and V a t th e tim e when t h e c o rp u s lu teu m horm one, p r o g e s te r o n e, was a t o r re a c h in g i t s h ig h e s t t i t e r s. The h ig h e r mean g ly cém ie v a lu e (104*5 mg p e r c e n t) o c c u re d d u rin g s ta g e s X and I I w h ile e s tro g e n was re a c h in g i t s maximum t i t e r s (h isaw ^ a ^, * 3 4 ), The i n t e r e s t i n t h i s i s r a t h e r o b v io u s i f one r e f e r s t o th e w ork o f G aunt ^ a^i ( *39) who found t h a t i n j e c t i o n o f p ro g e s te ro n e i n f e r r e t s e l e v a te d both l i v e r g ly co g en and b lo o d s u g a r. T hese ex p e r im e n ta l r e s u l t s, how ever, d id n o t h o ld t r u e f o r r a t s. I n d u c tiv e re a s o n in g w ould le a d t o th e c o n c lu s io n t h a t i f r a t s d id have a p e r io d o f o v a r ia n in f lu e n c e d h ig h b lo o d s u g a rs i t w ould o c c u r a t th e tim e c f h ig h p ro g e s te r o n e t i t e r s. F u r th e r s u p p o rt f o r t h i s h y p o th e s is a c c ru e s from th e work of F o g lia etg, â i ( *47) in t h e i r w ork w ith 95% p a n c re a te c to m iz e d a n im a ls. They found t h a t e s t r a d i o l e x e r te d a p r o t e c t i v e e f f e c t a g a in s t d ia b e te s in c id e n c e * They a l s o n o te d a se x d i f f e r e n c e in c a s e s o f

38 *"32 d i a b e t e s, w ith fe m a le s b e in g l e s s s u s c e p t i b le th a n m ales* Lew is s!k (*50) i n a c o n tin u a tio n o f th e above s tu d y fo und i n m ale and fe m a le c a s t r a t e s, p a n c re a te c to m iz e d, t h a t e s tr o g e n s re d u c e d t h e num ber o f d i a b e t i c c a s e s in b o th p o p u la tio n s ; p r o g e s te ro n e and d e s o x y c o rtic o s te ro n d id n o t m odify th e num ber o f i n c i d e n c e s and t h a t a n d ro g e n s in c r e a s e d th e s u s c e p t i b i l i t y to d i a b e t e s. I n my r e s u l t s, th e s p e c u la tio n t h a t th e h ig h e s t b lo o d s u g a r t i t e r s would o c c u r d u rin g th e p ro g e s te ro n e s e c r e to r y phase o f th e o v ary d id n o t h o ld t r u e ; i n f a c t th e co n v e rse o f t h i s s i t u a t i o n was found t o occur* The d i f f e r e n c e s betw een th e mean b lo o d s u g a rs w ere n o t g r e a t, b u t were r a t h e r c o n s ta n t* The h ig h e s t v a lu e s w ere found i n th e r e p ro d u c tiv e c y c le phase w here e s tr o g e n was dom inant* The o n ly s u p p o rt f o r t h e s e f in d in g s t h a t th e l i t e r a t u r e w ould seem t o o f f e r comes from th e b a s a l m etab o li c r a t e d e te r m in a tio n s of Lee (*20) i n w hich he found in c r e a s e d m e ta b o lic r a t e s i n t h e p e r io d o f co rp u s luteum d e g e n e ra tio n * He s u g g e ste d th e p o s s i b i l i t y t h a t th e co rp u s lu teu m m ight have au a n a b o lic f u n c ti o n, and t h a t upon r e m oval o f i t s in f lu e n c e in c r e a s e d c a ta b o lic a c t i v i t y o ccu rs* The p o s s i b i l i t y o f some o th e r i n t r i n s i c f a c t o r g iv in g r i s e t o a c y c li c v a r i a t i o n i n b lo o d s u g a r r e a d in g s, w hich m ight m is ta k e n ly be a t t r i b u t e d t o th e o v a r ia n c y c le was