CONTROL OF TORPOR AND BODY-WEIGHT PATTERNS BY A SEASONAL TIMER IN SIBERIAN HAMSTERS
CONTROL OF TORPOR AND BODY-WEIGHT PATTERNS BY A SEASONAL TIMER IN SIBERIAN HAMSTERS
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DOI：
10.1152/ajpregu.1989.257.1.r142
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发表时间：
1989-07-01
影响因子：
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通讯作者：
GOLDMAN, BD
中科院分区：
文献类型：
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作者：
BARTNESS, TJ;ELLIOTT, JA;GOLDMAN, BD
设计了两个实验来评估西伯利亚仓鼠（Photopus sungorus sungorus）所表现出的短日照诱导的浅日麻痹、体重和其他季节性反应（食物摄入和皮毛色素沉着）模式是否受独立于生殖状态的“季节性计时机制”控制[睾酮，（T）]。我们检查了这些季节性反应的模式和表达是否被短日照暴露的前8周期间伴随性腺退化的血清T降低所改变（即，休眠季节的“准备阶段”）或在此阶段之后血清T的实验性增加。短日照饲养的去势仓鼠带有T植入物，其激素水平为长日照，且未表现出麻木。适当的季节性模式和水平的麻木，体重，皮毛颜色阶段，和食物摄入量后，T植入物去除，虽然血清T被夹在长日水平在准备阶段。在准备阶段性腺完整的动物中，随后被阉割并给予T植入物，只要植入物在适当的位置，就不会发生麻木。然而，与去势、空白植入对照组相比，T植入物取出时的每日麻痹模式和水平、食物摄入量和体重迅速恢复至适当的季节值;无论T植入物是否在麻痹频率增加、达到峰值或在整个麻痹季节减少时取出，都会发生这些影响。在任何条件下，T对毛色阶段均无影响。总的来说，这些结果表明，西伯利亚仓鼠具有季节性的计时机制，精确地管理模式的短日诱导的麻木，体重和食物摄入量，是不受实验升高血清T长日水平。
Two experiments were designed to assess whether the short-day-induced patterns of shallow daily torpor, body weight, and other seasonal responses (food intake and pelage pigmentation) exhibited by Siberian hamsters (Phodopus sungorus sungorus) are under the control of a "seasonal timekeeping mechanism" that is independent of reproductive status [testosterone, (T)]. We examined whether the patterning and expression of these seasonal responses were altered by decreases in serum T that accompany gonadal regression during the first 8 wk of short-day exposure (i.e., the "preparatory phase" of the torpor season) or by experimental increases in serum T after this phase. Short-day-housed, castrated hamsters bearing T implants had long-day levels of the hormone and did not exhibit torpor. Appropriate seasonal patterns and levels of torpor, body weight, pelage color stage, and food intake were exhibited after T implant removal although serum T was clamped to long-day levels during the preparatory phase. In animals that were gonad intact during the preparatory phase and were subsequently castrated and given T implants, torpor did not occur as long as the implants were in place. However, the patterns and levels of daily torpor, food intake and body weight rapidly returned to appropriate seasonal values compared with the castrated, blank-implanted controls on T implant removal; these effects occurred whether the T implants were removed when torpor frequency was increasing, at its peak, or decreasing across the torpor season. T did not affect pelage color stage under any condition. Collectively, these results suggest that Siberian hamsters possess a seasonal timekeeping mechanism that precisely governs the pattern of short-day-induced torpor, body weight, and food intake and is unaffected by experimentally elevating serum T to long-day levels.