The effects of leptin hormone on locomotor activity in Syrian hamsters (Mesocricetus auratus)

Authors : Bülent GÜNDÜZ, Alper KARAKAŞ

Pages : 727-734

View : 17 | Download : 11

Publication Date : 2011-12-01

Article Type : Research Paper

Abstract :The suprachiasmatic nucleus insert ignore into journalissuearticles values(SCN); generates and controls the circadian rhythms in mammals including the rhythm of locomotor activity. Leptin is a hormone secreted by adipose tissue that informs the brain about the fat stores. SCN neurons express leptin receptors. Here we investigated the effects of 3 different leptin administrations on the locomotor activity of the Syrian hamsters maintained in constant darkness. Animals were intraperitoneally insert ignore into journalissuearticles values(ip); injected insert ignore into journalissuearticles values(4 µg/kg);, subcutaneously insert ignore into journalissuearticles values(sc); infused insert ignore into journalissuearticles values(4 µg/kg);, or intra-SCN infused insert ignore into journalissuearticles values(0.4 µg/kg); with leptin for 3 days at circadian time 10 whereas the controls received saline insert ignore into journalissuearticles values(0.9% NaCl); at the same time in order to eliminate stress factors. Our results demonstrate that the locomotor activity of the hamsters can be phase advanced by the external leptin administrations. Leptin affected the level of phase-shifts in an administration method-dependent manner. The biggest phase advance was observed in intra-SCN infusion insert ignore into journalissuearticles values(P = 0.001);, and the smallest was in the ip injection insert ignore into journalissuearticles values(P = 0.041); group. The wheel-turn amounts did not change significantly in the groups before and after the leptin administrations insert ignore into journalissuearticles values(P = 0.233);; however, the period lengths increased insert ignore into journalissuearticles values(P = 0.011); significantly after leptin administrations. These results suggest for the first time that in vivo leptin administrations may change the rhythm of locomotor activity in adult male Syrian hamsters.
Keywords : Key words SCN, locomotor activity, leptin, Syrian hamster, Mesocricetus auratus