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The Suppressor of Cytokine Signalling 3, SOCS3, may be One Critical Modulator of Seasonal Body Weight Changes in the Siberian Hamster, Phodopus sungorus
Author(s) -
Tups A.,
Barrett P.,
Ross A. W.,
Morgan P. J.,
Klingenspor M.,
Mercer J. G.
Publication year - 2006
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.2005.01394.x
Subject(s) - phodopus , socs3 , endocrinology , medicine , hamster , biology , cytokine , suppressor of cytokine signaling 1 , body weight , suppressor , microbiology and biotechnology , signal transduction , gene , stat3 , genetics
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.