关键词: 短光照, 产热, 达乌尔黄鼠

Abstract: Thermogenesis and thermoregulation induced by short photoperiod were investigated in Daurian ground squirrels (Spermophilus dauricus) by measuring resting metabolic rate (RMR), nonshivering thermogenesis (NST),activity of cytochrome C oxidase (CCO) of liver and brown adipose tissues (BAT), BAT mitochondrial GTP-binding capacity, and hypothalamic thyrotropin-releasing hormone (TRH) and corticotrophin-releasing hormone (CRH) levels in squirrels. The results showed that the RMR,NST,CCO activity, and BAT mitochondrial GTP-binding capacity were markedly increased by exposure to short photoperiod (8D∶16L,SP)and constant ambient temperature (22 ± 2℃ ) relative to those for long photoperiod (16D∶ 8L,22 ± 2℃ ,LP),while body weight and BAT mass,hepatic mitochondrial respiration,and BAT α-glycerophosphate oxidase activity were not significantly hanged. The short photoperiod induced higher hypothalamic TRH and CRH levels than did the LP. However, the serum concentration of triiodothyronine (T₃ ),thyroxine (T₄ ), the ratio of T₃ and T₄, the activity of T₄ 5'-deiodinase in BAT, and the adrenal corticosterone level showed no significantly change. The results suggest that the short photoperiod may induce an increased thermogenesis in Daurian ground squirrel’s through activating CCO and enhancing ncoupling-protein levels in BAT, and simultaneously activating hypothalamic TRH and CRH that do not directly induce an increased hermogenesis but may be a potential factor.

Key words: Daurian ground squirrel (Spermophilus dauricus), Short photoperiod, Thermogenesis