Tups A, Barrett P, Ross A W, Morgan P J, Klingenspor M, Mercer J G
Division of Obesity and Metabolic Health, Rowett Research Institute, Aberdeen Centre for Energy Regulation and Obesity, ACERO, Aberdeen, Scotland, UK.
J Neuroendocrinol. 2006 Feb;18(2):139-45. doi: 10.1111/j.1365-2826.2005.01394.x.
The Siberian hamster, Phodopus sungorus, exhibits a remarkable cycle of body weight, reproduction and leptin sensitivity in response to a seasonal change in photoperiod. In the present study, we investigated the hypothesis that the suppressor of cytokine signalling 3 (SOCS3) plays a critical role in the regulation of the seasonal body weight cycle. We analysed arcuate nucleus SOCS3 gene expression in short day length (SD; 8 : 16 h light/dark) acclimated Siberian hamsters that were transferred back to long day length (LD; 16 : 8 h light/dark) and in hamsters that spontaneously became photorefractory to SD induced by prolonged exposure. SD acclimated hamsters that were transferred back to LD for 1, 2, 3, 4 or 6 weeks, increased arcuate nucleus SOCS3 gene expression to the LD level within 2 weeks, and maintained this higher level thereafter. The early increase of SOCS3 gene expression preceded the LD-induced rise in body weight by approximately 3 weeks. Hamsters kept in SD for an extended period (25 weeks), began to become refractory to SD and to increase body weight. By this time, there was no difference in level of SOCS3 gene expression between LD and SD photoperiods, although body weight was still suppressed in SD hamsters. Finally, we addressed whether SOCS3 gene expression is related to SD-induced gonadal regression or to body weight decrease by comparing Siberian hamsters with Syrian hamsters. The latter exhibited substantial SD-induced gonadal regression but only limited seasonal changes in body weight. Acclimation to either LD or SD for 14 weeks had no effect on SOCS3 gene expression. This implies that arcuate nucleus SOCS3 gene expression is unlikely to be related to seasonal cycles in reproductive activity. Taken together, the findings further strengthen our hypothesis that SOCS3 may be one molecular trigger of seasonal cycles in body weight.
西伯利亚仓鼠（Phodopus sungorus）会根据光周期的季节性变化展现出显著的体重、繁殖和瘦素敏感性周期。在本研究中，我们探讨了细胞因子信号传导抑制因子3（SOCS3）在季节性体重周期调节中起关键作用这一假说。我们分析了适应短日照（SD；8:16小时光照/黑暗）的西伯利亚仓鼠的弓状核SOCS3基因表达，这些仓鼠被转移回长日照（LD；16:8小时光照/黑暗）环境，以及因长期暴露而对SD自发产生光不应性的仓鼠。适应SD的仓鼠被转移回LD环境1、2、3、4或6周后，弓状核SOCS3基因表达在2周内增加到LD水平，并在此后维持这一较高水平。SOCS3基因表达的早期增加比LD诱导的体重增加提前约3周。长时间（25周）处于SD环境的仓鼠开始对SD产生不应性并体重增加。此时，尽管SD仓鼠的体重仍受到抑制，但LD和SD光周期下的SOCS3基因表达水平没有差异。最后，我们通过比较西伯利亚仓鼠和叙利亚仓鼠来探讨SOCS3基因表达是否与SD诱导的性腺退化或体重下降有关。后者表现出显著的SD诱导性腺退化，但体重的季节性变化有限。适应LD或SD环境14周对SOCS3基因表达没有影响。这表明弓状核SOCS3基因表达不太可能与生殖活动的季节性周期有关。综上所述，这些发现进一步强化了我们的假说，即SOCS3可能是体重季节性周期的一个分子触发因素。
