Memory-enhancing effects of the leptin hormone in Wistar albino rats: sex and generation differences

Transcription

1 Turkish Journl of Biology Rsrh Artil Turk J Biol (2013) 37: TÜBİTAK oi: /iy Mmory-nhning ffts of th lptin hormon in Wistr lino rts: sx n gnrtion iffrns Alpr KARAKAŞ 1, *, Hmit COŞKUN 2, Fvziy Umut KIZILKAYA 1 1 Dprtmnt of Biology, Fulty of Arts n Sins, Ant İzzt Bysl Univrsity, Bolu, Turky 2 Dprtmnt of Psyhology, Fulty of Arts n Sins, Ant İzzt Bysl Univrsity, Bolu, Turky Riv: Apt: Pulish Onlin: Print: Astrt: Lptin is hormon srt y ipos tissu tht informs th rin out th ft stors of th oy. In this stuy, w xmin th ffts of tim lptin injtions on sptil mmory prformns of ult n juvnil ml n fml Wistr rts with th Morris wtr mz tst. W ppli th injtions n onut th trining trils for 4 ys. On th fifth y ftr lptin injtions, th xprimnts wr prform. Th tivitis wr ror n nlyz with th Nolus Ethovision Animl Vio Trking Systm. Th rsults show tht th sptil mmory prformn of th rts ws improv y th lptin injtions sin thy shortn th ltny to fin th pltform n longt th tim spnt in th orrt qurnt. Th g of th rts ws foun to importnt sin th ults foun th pltform fstr thn th juvnils. Thr ws n intrtion fft twn sx n gnrtion in ll prmtrs xmin xpt for th tim spnt in th orrt qurnt. Th rsults of th prsnt stuy suggst tht lptin ministrtion vi tim injtions strngthns sptil mmory in Wistr lino rts, ut this fft pns upon th sx n th gnrtion of th rts. Ky wors: Lptin, Morris wtr mz, sptil mmory 1. Introution Lptin, th protin prout of th os gn, is irulting hormon prou primrily y ipos tissu n is known to ply ky rol in rgulting fing n oy ft stors (1,2). It is involv in vrious physiologil vnts inluing rproution, hmtopoisis, ngiognsis, woun hling, insulin srtion, n nuroprottion (3). Th rls of lptin xhiits 24-h rhythm tht vris in timing twn iffrnt lortory ront spis (4). In mi n rts, srum lptin onntrtions n mrna ontnt of lptin in ipos tissu rs in th light phs n inrs in th rk phs (5 7). Th stor ft in th whit ipos tissu informs th ntrl nrvous systm vi lptin out th mount of nrgy vill for iffrnt purposs, suh s rproution. Synpti plstiity n hviorl prformn rlt to lrning n mmory my moult y th hormon lptin (8). Thr is growing vin tht o-r, th long form of th lptin rptor, is xprss in th othr ntrl nrvous systm rgions suh s th hippompus, mygl, n noortx, whih r known to ssoit with mmory n ognitiv funtions (8). Lptin rptors r foun in th hippompus n mygl (8). Lptin xists in th hippompus to filitt long-trm potntiting, whih is importnt for * Corrsponn: krks_@iu.u.tr 222 th oprting pross of mmory. Although low os of lptin inrss long-trm potntiting n hviorl prformn, high os of lptin impirs thm (8). In ronts, lptin rptor fiiny my l to n impirmnt of sptil mmory funtion (9). Sx iffrns hv n rport in trms of th mount of irulting lptin lvls (10,11). Fmls gnrlly hv grtr prntg of oy ft thn mls of similr oy wight or oy mss inx; thrfor, lptin lvls r grtr in fmls thn in mls of quivlnt ft mss (12). Thr r 2 plusil xplntions for this iffrn. First, fmls hv mor suutnous ft thn mls, n lptin srtion hs n rport to grtr in suutnous ipoyts thn omntl ons for th sm sujt (13,14). Th son is th nognous hormonl miliu, with strogns gnrlly rport to inrs lptin proution (15) n tstostron or nrogns to supprss lptin lvls (16 18). Dspit ths nvors in th litrtur, th fft of lptin with sx on th sptil mmory still is not known. Givn th ft tht fmls hv highr lvl of lptin thn mls n lptin hs nfiil fft on lrning, it n hypothsiz tht fmls r ttr t sptil lrning thn mls.

2 KARAKAŞ t l. / Turk J Biol Srum lptin onntrtion is highly orrlt with g n ipos tissu mss (19,20). Rts tn to gin wight s thy g. Totl lptin mrna lvls in rts inrs with g, pking t 24 months, n r orrlt with iposity. Srum lptin lvls inrs with g, lso pking t 24 months, n r orrlt with totl lptin mrna. Th rt of inrs in srum lptin is grtr thn th inrs in iposity with g, suggsting ontriutions from oth th inrs in lptin xprssion pr unit of whit ipos tissu (WAT) n th inrs in WAT pot siz (21). Givn th litrtur fining tht lptin filitts lrning, ults shoul show ttr lrning prformn thn juvnils sin th lptin lvls r highr in ults thn juvnils. Howvr, suh suggstion hs not yt n onfirm in th litrtur sin thr is no rsrh tht xmins th fft of lptin with g on sptil mmory. Evn though thr hv n som stuis tht xmin ffts of lptin, sx, n gnrtion on iffrnt lrning mols, ths stuis i not invstigt th ffts of ths vrils in singl rsrh prigm tht nls rsrhrs to ompr th ffts of ths vrils togthr. Givn th onsirtions mntion ov, th prsnt stuy ws onut to invstigt th ffts of lptin trtmnt (lptin injtion n slin injtion), sx (ml n fml), n gnrtion (juvnils n ults) on th sptil mmory prformn of rts in Morris wtr mz. 2. Mtrils n mthos 2.1. Animl r Ault ml Wistr rts ( g) wr otin from our lortory olony mintin t Ant İzzt Bysl Univrsity (AİBU). Thy wr xpos from irth to 12 h of light n 12 h of rknss, with lights off t 1800 hours. Animls wr mintin in plsti gs ( m) with pin shvings us s ing. Foo pllts n tp wtr wr ssil liitum. Th prours in this stuy wr rri out in orn with th institution s sintifi prours for nimls n ws pprov y th Institutionl Animl Cr n Us Committ. All lighting ws provi y ool-whit fluorsnt tus ontroll y utomti progrmml timrs. Amint tmprturs in th niml filitis wr hl onstnt t 22 ± 2 C in ir-vntilt rooms Exprimntl protool In th prsnt stuy, totl of 120 rts wr us: 60 ml (n: 28) n fml (n: 32) ult rts (6 months ol), n 60 ml (n: 28) n fml (n: 32) juvnil rts (1 month ol). Thy wr rnomly ivi into ithr th lptin injtion or th slin injtion group. Th sptil mmory of th Wistr rts ws msur t 1800 hours y mns of Morris wtr mz tst Lptin ministrtions Lptin (Sigm) ws issolv in thnol n furthr ilut in slin; it ws injt in os of 10 µg/kg t 1700 hours intrpritonlly for 5 ys. Slin ws injt with th sm mount of lptin Morris wtr mz To tst sptil mmory, th prformns of th rts in th Morris wtr mz wr vlut. Th xprimnts wr rri out in irulr, glvniz stl mz (1.5 m in imtr n 60 m in pth), whih ws fill 40 m p with wtr kpt t 28 C n rnr opqu y th ition of nontoxi, wtr solul y. Th mz ws lot in lrg, quit tst room, surroun y mny visul us xtrnl to th mz (.g., th xprimntr, iling lights, rk, piturs), whih wr visil from within th pool n oul us y th rts for sptil orinttion. Th lotions of th us wr unhng throughout th prio of tsting. A vio mr fix to th iling ovr th ntr of th mz ws us for roring n monitoring th movmnts of th nimls. Thr wr 4 qully ivi qurnts in th pool. In on of th qurnts, pltform (1.0 m low th wtr surf, 10 m in imtr) ws sumrg ntrlly n fix in position tht ws kpt onstnt throughout th quisition trils. Th rts prform 4 trils pr y for 4 onsutiv ys (16 trils). In th swimming trils, h iniviul rt ws rls gntly into th wtr t hosn qurnt, xpt for th on tht ontin th hin pltform, to f n xtr mz u. Th rts swm n lrn how to fin th hin pltform within 60 s. Esp ltny, whih is th tim lps for th rt rhs th pltform in h tril, is msur of th quisition of sptil nvigtion. Aftr rhing th pltform, th rt ws llow to sty on it for 15 s n ws thn tkn k into th g. During th intrtril intrvls, th nimls wr kpt in ry hom g for 60 s. A pltform (10 m in imtr) ws pl in 1 of th 4 mz qurnts (th trgt qurnt) n sumrg 1.5 m low th wtr surf. Th pltform rmin in th sm qurnt throughout th xprimnt. Th rts wr rquir to fin th pltform using only istl sptil us vill in th tsting room. Th us wr mintin onstnt throughout th tsting. Th rts unrwnt 4 onsutiv ily trining trils. Vio mr rorings wr otin on th fifth y of th xprimnt. Eh rt h to swim until it lim onto th pltform sumrg unrnth th wtr. Th sp pltform ws kpt in th sm position rltiv to th istl us. Th tim to rh th pltform (ltny in sons), totl istn trvll, tim pss in th orrt qurnt, ntrn frquny to th orrt qurnt, n immoility wr msur s th inxs of th sptil mmory. In this xprimnt, vio mr (Gk CC-28905S, Commt LTD. ŞTİ., 223

3 KARAKAŞ t l. / Turk J Biol Ankr, Turky) ws mount ov th rn, roring hvior into th Ethovision Vio Trking Systm (Nolus Ethovision, Vrsion 6, Nthrln; Commt LTD.ŞTİ. Ankr/Turky), whih provi vrity of hviorl msurs inluing istn, tim on th g, tim in th ntr, frquny on th g, frquny in th ntr, n immoility mong th iffrnt rs of th rn. All nimls wr thn rturn to th ring n xhiition olonis Sttistil nlyss Dt wr nlyz using SPSS Dt wr xmin y mns of 2 (th prsn of trtmnt: lptin injtion n ontrol (shm) group) 2 (sx: ml n fml) 2 (gnrtion: juvnils n ults) twn ANOVA sign. Vlus wr onsir sttistilly signifint t P < Dt r prsnt s mn ± stnr rror ftr k trnsforming from ANOVA rsults. Nonsignifint finings wr not rport in this rtil u to limit sp. 3. Rsults 3.1. Totl istn trvll in th Morris wtr mz Th min fft of lptin ministrtion ws signifint on th totl istn trvll in th Morris Wtr mz, F (1, 112) = 4.41, P = 0.04, η 2 = Lptin-ministr sujts (M = ) trvll lss istn thn slininjt sujts (M = ) (Figur 1). Totl istn trvll (m) TDT Ml Fml Ml Fml Ault Figur 1. Th totl istn trvll (TDT) in th Morris wtr mz is rprsnt. Th right-strit r rprsnts slin injtion () for ult n juvnil mls n th lk r rprsnts lptin injtion (Lp.) for ult n juvnil mls. Th ross-strit r rprsnts slin injtion () for ult n juvnil fmls n th rik-strit r rprsnts lptin injtion (Lp.) for ult n juvnil fmls. Dt r prsnt s mns ± stnr rror. Diffrnt lttrs init th sttistilly iffrnt groups (t lst ll P < 0.05). Th sttistil vlus of th groups n sn in th rlvnt txt. Th min fft of gnrtion ws signifint on th totl istn trvll in th Morris wtr mz, F (1, 112) = 11.03, P = 0.001, η 2 = Aults (M = ) trvll lss istn thn juvnils (M = ). Th intrtion fft twn gnrtion n trtmnt ws signifint, F (1, 112) = 3.76, P = 0.05, η 2 = Evn though th iffrn twn lptin-ministr ults (M = ) n slin-injt ults (M = ) ws not signifint in trms of istn trvll, lptinministr juvnils (M = ) trvll signifintly lss istn thn slin-injt ons (M = ). Th intrtion fft twn gnrtion n sx ws lso signifint, F (1, 112) = 16.87, P = , η 2 = In ults, mls trvll (M = ) lss istn thn fmls (M = ), whrs in juvnils, fmls (M = ) trvll signifintly lss istn thn mls (M = ) Tim spnt to fin th pltform Th min fft of lptin ministrtion ws signifint on th tim spnt to th fin th pltform on th Morris Wtr mz, F (1, 112) = 4.19, P = 0.04, η 2 = Lptinministr sujts (M = 13.36) spnt lss tim thn slin-injt sujts (M = 17.75) (Figur 2). Th min fft of gnrtion ws lso signifint on th tim spnt to th fin th pltform in th Morris wtr mz, F (1, 112) = 13.37, P = , η 2 = Aults (M = 11.96) spnt lss tim to fin th pltform thn juvnils (M = 18.85). Th intrtion fft twn gnrtion n trtmnt ws signifint, F (1, 112) = 5.45, P = 0.02, η 2 = Evn though th iffrn twn lptinministr ults (M = 11.95) n slin-injt ults (M = 11.33) ws not signifint in trms of tim spnt Tim spnt to fin th pltform (s) TSFP (Ltny) Ml Fml Ml Fml Ault Figur 2. Th tim spnt to fin th pltform (TSFP) or ltny in th Morris wtr mz is rprsnt. Th r xplntions ppr unr Figur

4 KARAKAŞ t l. / Turk J Biol to fin th pltform, lptin-ministr juvnils (M = 14.76) spnt signifintly lss tim thn slin-injt ons (M = 24.09). Furthrmor, th intrtion fft twn gnrtion n sx ws lso signifint, F (1, 112) = 6.90, P = 0.01, η 2 = In ults, mls spnt (M = 7.60) lss tim thn fmls (M = 15.69), whrs in juvnils, fmls (M = 17.88) spnt signifintly lss tim thn mls (M = 20.98) Tim spnt in th orrt qurnt Th intrtion fft twn sx n trtmnt ws signifint, F (1, 112) = 5.695, P = 0.02, η 2 = Lptinministr mls (M = 0.10) spnt mor tim in th orrt qurnt thn slin-injt mls (M = 0.07), whrs slin-ministr fmls (M = 0.09) spnt mor tim in th orrt qurnt thn lptinministr fmls (M = 0.07) (Figur 3) Th ntrn frquny to th orrt qurnt Th min fft of gnrtion ws signifint on th ntrn frquny to th orrt qurnt in th Morris wtr mz, F (1, 112) = 10.96, P = 0.001, η 2 = s (M = 2.03) ntr th orrt qurnt mor frquntly thn ults (M = 1.50) (Figur 4). Th intrtion fft twn sx n gnrtion ws signifint, F (1, 112) = 10.96, P = 0.001, η 2 = Ault fmls (M = 1.69) ntr mor frquntly thn ult mls (M = 1.25), whrs juvnil mls (M = 2.46) ntr mor frquntly thn juvnil fmls (M = 1.69) Moility tim Th min fft of th lptin ministrtion ws signifint on moility, F (1, 112) = 21.89, P = , η 2 = Lptin-ministr sujts (M = 0.01) wr lss moil thn slin-injt sujts (M = 0.03) (Figur 5). Tim spnt in orrt qurnt (min) TSCQ Ml Fml Ml Fml Ault Figur 3. Th tim spnt in th orrt qurnt (TSCQ) of th Morris wtr mz is rprsnt. Th r xplntions ppr unr Figur 1. f Entrn frquny to orrt qurnt EFCQ Ml Fml Ml Fml Ault Th min fft of gnrtion ws signifint on moility, F (1, 112) = 26.12, P = , η 2 = s (M = 0.03) wr mor moil thn ults (M = 0.009). Th min fft of th sx ws signifint on th moility, F (1, 112) = 8.52, P = 0.004, η 2 = Mls (M = 0.02) wr mor moil thn fmls (M = 0.01). Th intrtion fft twn gnrtion n trtmnt ws signifint, F (1, 112) = 12.18, P = 0.001, η 2 = Lptin-ministr ults (M = 0.006) wr lss moil thn slin-injt ults (M = 0.01), n lptinministr juvnils (M = 0.01) wr lss moil thn slin-injt ons (M = 0.05). Th iffrn ws grtr in juvnils. Figur 4. Th ntrn frquny to th orrt qurnt (EFCQ) in th Morris wtr mz is rprsnt. Th r xplntions ppr unr Figur 1. Moility tim (min) MT Ml Fml Ml Fml Ault Figur 5. Th moility tim (MT) in th Morris wtr mz is rprsnt. Th r xplntions ppr unr Figur

5 KARAKAŞ t l. / Turk J Biol Vloity (m/min) VEL Ml Fml Ml Fml Ault Figur 6. Th vloity (VEL) in th Morris wtr mz is rprsnt. Th r xplntions ppr unr Figur 1. Th intrtion fft twn trtmnt n sx ws signifint, F (1, 112) = 10.04, P = 0.002, η 2 = Lptininjt mls wr lss moil (M = 0.01) thn slininjt mls (M = 0.05), whrs thr ws no signifint iffrn twn lptin n slin-ministr fmls (M = 0.01), whih trvll signifintly lss istn thn mls (M = 0.02). Th intrtion fft twn gnrtion n sx ws lso signifint, F (1, 112) = 34.99, P = , η 2 = Ault mls wr lss moil (M = 0.001) thn ult fmls (M = 0.02), whrs juvnil fmls (M = 0.01) wr lss moil thn juvnil mls (M = 0.05) Vloity Th min fft of sx ws signifint on vloity, F (1, 112) = 5.47, P = 0.02, η 2 = Mls (M = ) wr fstr thn fmls (M = ) (Figur 6). Th intrtion fft twn gnrtion n sx ws signifint, F (1, 112) = 23.15, P = , η 2 = mls (M = ) wr fstr thn juvnil fmls (M = ); howvr, ult mls (M = ) n fmls (M = ) wr not signifintly iffrnt from h othr. 4. Disussion Th im of th prsnt stuy ws to invstigt th fft of lptin hormon injtion on th sptil mmory prformn of Wistr lino rts in th Morris wtr mz. Th Morris wtr mz is on of th most suitl tsts for th invstigtion of sptil mmory (22). In this tst, th niml is trying to fin hin pltform tht is foun low th wtr lvl y using us roun th xprimntl r. Th tim tkn to fin th pltform, th tim spnt in th orrt qurnt, n th ntrn frqunis to th orrt n inorrt qurnts r us s th prmtrs rprsnting th sptil mmory n lrning prformn of th nimls. Sin our fous ws on sptil mmory, w us th Morris wtr mz tst. In sum, th rsults of this stuy init tht () lptin injtion nhn sptil mmory prformn in trms of istn trvll, tim spnt to fin th pltform (ltny), n moility; () ults show ttr sptil mmory prformn in trms of istn trvll, tim spnt to fin th pltform, frquny of ntrn to th qurnt of th pltform, n moility; n () mls wr mor moil n fstr thn fmls. Lptin rptors r foun in th hippompus n th mygl (8). Thr is vin tht, in ronts, lptin rptor fiiny impirs sptil mmory funtion (23). In th prsnt stuy, lptin injtion my hv h irt fft y ining to ths rptors n thry inrsing th tivitis of ths rin rgions. Sin ths rin rgions r rsponsil for mmory, suh tivtion my improv sptil mmory. In ition to this irt fft, lptin my hv lso inirt ffts on lrning n mmory y t lst 2 mhnisms. First, lptin filitts long-trm potntition, whih is importnt for th oprting pross of mmory (9). Long-trm potntition is on form of tivity-pnnt synpti plstiity (24 26), whih is prt of th nurophysiologil sis of lrning n mmory (27). Thus, th mmory-nhning proprtis of th lptin my ttriut to th longtrm potntition filitt y th lptin. Son, thr is vin tht lptin rss nxity in mi (28). Th nxiolyti ffts of lptin my prou filittory fft on srhing for th pltform in th orrt qurnt. Thr is vin tht lptin lvls ris in nontl mi, n this my rgult th postntl vlopmnt of th nuronorin xis (5,29). Lptin fiiny hs rntly n foun to ru rin wight, nuronl som siz, n th synthsis of synpti protins n of glil firillry ii protin in th hippompus n noortx. It lso ls to fiinis in rin mylin (30). Thrfor, in th urrnt stuy, lptin implmnttion my hv hlp to nhn th synthsis of synpti protins n synpti ommunition mong th nurons in hippompus n noortx, whih r importnt omponnts for th sptil mmory. W implmnt 10 µg/kg of lptin, whih is onsir to low lvl. Our finings r onsistnt with th prvious rsrh finings (8). In ition to ths min ffts, thr wr lso intrtion ffts twn th invstigt vrils. Spifilly, lptin-ministr juvnils trvll signifintly lss istn thn slin-injt ons; lptinministr juvnils spnt signifintly lss tim thn slin-injt ons; lptin-ministr fmls spnt 226

6 KARAKAŞ t l. / Turk J Biol lss tim in th orrt qurnt thn slin-ministr fmls; n ult fmls ntr mor frquntly thn ult mls, whrs juvnil mls ntr mor frquntly thn juvnil fmls. In trms of th intrtion fft twn lptin trtmnt n gnrtion, our t suggst tht in ults high lvl of nognous lptin is mor fftiv thn xognous lptin ministrtion. In th prsnt stuy, w i not fin signifint vin for th nfiil fft of th lptin ovr th slin onition on th sptil mmory prformn of ults. Rts tn to gin wight s thy g. Along with this inrs in wight, th totl lptin mrna lvls in rts lso inrs with g (19,20). Thrfor, this fining of our stuy oul ttriut to th ft tht th lptin rptors my los thir snsitivity to xognous lptin in ults sin thy lry hv high lvls of nognous lptin. W lso foun tht oth lptin-ministr ults n juvnils wr lss moil thn slin-injt ults n juvnils. This n ttriut to th moultion of th hypothlmi fing n nrgy xpnitur iruits y lptin (19,31,32). Lptin supprsss foo intk ut stimults nrgy onsumption (33). In th prsnt stuy, xognous ministrtion of th lptin hormon my hv inrs th rt of sl mtolism. Sin nrgy storg is limit, nimls my pt to this nw onition (lvtion of sl mtolism) y rsing moility in th rn of th wtr mz. Futur rsrh shoul xmin th plusil intrtion ffts twn lptin trtmnt n gnrtion on mmory n thir unrlying mhnisms for suh fft in grtr til. Morovr, th prsnt stuy show tht in ults, mls trvll lss istn thn fmls, whrs in juvnils, fmls trvll signifintly lss istn thn mls; in ults, mls spnt lss tim thn fmls, whrs in juvnils, fmls spnt signifintly lss tim thn mls; ult mls wr lss moil thn ult fmls, whrs juvnil fmls wr lss moil thn juvnil mls; n juvnil mls wr fstr thn juvnil fmls. In othr wors, in ults, mls lrn ttr thn fmls, whrs in juvnils, fmls lrn ttr thn mls. Th prsnt fining initing tht, in juvnils, fmls lrn ttr thn mls is onsistnt with th rnt rsrh fining tht fml rts prform signifintly ttr thn ml rts in rognition tsk (34). This onsistnt vin ws lso onfirm y th rsrh fining in humn stuis tht fmls show ttr rognition prformn thn mls (35). This onsistnt fining n xplin from 3 prsptivs: iffrnt lptin lvls twn mls n fmls, sltivity, n strogn iffrns twn mls n fmls. First, fmls gnrlly hv grtr prntg of oy ft thn mls of similr oy wight or oy mss inx; thrfor, lptin lvls r grtr in fmls thn in mls of quivlnt ft mss (12). Son, th sltivity hypothsis, whih ws vlop y Myrs-Lvy t l. (36), proposs tht fmls tn to pross informtion omprhnsivly, prossing ll vill informtion, oth rlvnt n irrlvnt. In ontrst, mls tn to pross informtion in mor sltiv fshion, fousing only on wht is rlvnt to th tsk or to thmslvs. Our rsults support this hypothsis, whih hs lso n rport to prtiulrly rlvnt to osrv sx iffrns in ognition whn it involvs rognition or lotion mmory (35,37,38). Thir, strogn iffrns twn mls n fmls my hv ontriut to th prsnt finings. Th hormon strogn n ply n importnt rol in rgulting sptil mmory. Initil stuis using th sptil ril rm mz suggst tht striol xrts iffrntil os-pnnt ffts on sptil working mmory prosss (39 42). Low lvls of striol ru working mmory rrors, whrs high lvls of striol inrs th numr of working mmory rrors rltiv to ovritomiz ontrol rts (42,43). Morovr, strogn my hv n inirt fft on lrning y inrsing lptin lvls. Thr is som vin tht n nognous hormonl miliu with strogns gnrlly inrss lptin proution (15). On th othr hn, this hormonl xplntion is not vli for mls sptil mmory prformn in ults sin thy show th st lrning prformn. Thr r t lst 2 plusil xplntions for this fft. First, mls tn to los thir sltivity (fousing only on wht is rlvnt to th tsk or to thmslvs) to thir nvironmnt n my inrs in prossing ll informtion rlt to thir surrounings from thir rognition mmory s thy g. Son, mls my mor ssrtiv in srhing for foo n fmls in thir nvironmnt s thy mtur. On th othr hn, fmls tn to spn lss tim srhing thir nvironmnt us thy must tk r of thir offspring for t lst som prio of tim. This my put som rstrition on th sptil mmory prformn of fmls. In onlusion, th rsults suggst tht lptin my hv nfiil fft on sptil mmory prformn. It shoul kpt in min tht th mmory-nhning ffts of lptin lso pn on sx n gnrtion in Wistr lino rts. Aknowlgmnt This stuy ws support y th AİBU Sintifi Rsrh Projt Unit ( ). 227

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