Several weeks of short day photoperiod (SD) exposure promote a dramatic decrease of white adipose tissue (WAT) mass in Siberian hamsters(Phodopus sungorus sungorus). This slimming effect is accompanied by changes in the adipocyte responsiveness to adrenergic stimulation that are still under debate. We investigated whether possible changes in the antilipolytic responses, and/or lipogenic activities could be involved in such lipid deposition/mobilisation imbalance. Male Siberian hamsters were exposed for 11 weeks to SD or long day photoperiod and basal or stimulated lipolytic and lipogenic activities were measured on white adipocytes. As expected, the body mass of SD-animals was decreased. Besides a slight reduction in the basal lipolysis and in the maximal response to dibutyryl-cAMP, the responses to adrenergic and non-adrenergic lipolytic agents (forskolin, adenosine deaminase) were similar in both groups. Fat mass loss was likely not resulting from changes in the lipolytic responses of adipocytes to biogenic amines (e.g. octopamine), which were unaltered, or to a direct lipolytic stimulation by melatonin or histamine, which were inactive. Antilipolytic responses to insulin or tyramine were slightly decreased in SD-adipocytes. Basal or insulin-stimulated lipid accumulation in WAT, measured by glucose incorporation into lipids, did not change after SD-exposure. However, a significant decrease in the lipoprotein lipase activity was observed in the WAT of SDanimals. Despite the observed changes, the weight loss of SD-exposed Siberian hamsters was likely not resulting only from impaired antilipolytic orde novo lipogenic activities in white adipocytes, but either from other dramatic changes occurring during seasonal photoperiod-sensitive body weight regulation.

中文翻译：

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暴露于短光周期的西伯利亚仓鼠（Phodopus sungorus sungorus）体重减轻的可能机制。

几周的短日光周期 (SD) 暴​​露促使西伯利亚仓鼠(Phodopus sungorus sungorus)的白色脂肪组织 (WAT) 质量急剧减少. 这种减肥效果伴随着脂肪细胞对肾上腺素能刺激的反应性的变化，这一点仍在争论中。我们研究了抗脂解反应和/或脂肪生成活动的可能变化是否与这种脂质沉积/动员失衡有关。雄性西伯利亚仓鼠暴露于 SD 或长日光周期 11 周，并在白色脂肪细胞上测量基础或刺激的脂肪分解和脂肪生成活动。正如预期的那样，SD 动物的体重下降了。除了基础脂肪分解和对二丁酰-cAMP 的最大反应略有减少外，两组对肾上腺素能和非肾上腺素能脂解剂（毛喉素、腺苷脱氨酶）的反应相似。脂肪量减少可能不是由脂肪细胞对未改变的生物胺（例如章鱼胺）的脂解反应的变化引起的，也不是由褪黑激素或组胺的直接脂解刺激引起的，这些反应是无活性的。SD-脂肪细胞对胰岛素或酪胺的抗脂解反应略有降低。通过将葡萄糖掺入脂质中来测量 WAT 中的基础或胰岛素刺激的脂质积累，在 SD 暴露后没有变化。然而，在 SDanimals 的 WAT 中观察到脂蛋白脂肪酶活性的显着降低。尽管观察到了变化，但暴露于 SD 的西伯利亚仓鼠的体重减轻可能不仅是由于抗脂解能力受损或 SD-脂肪细胞对胰岛素或酪胺的抗脂解反应略有降低。通过将葡萄糖掺入脂质中来测量 WAT 中的基础或胰岛素刺激的脂质积累，在 SD 暴露后没有变化。然而，在 SDanimals 的 WAT 中观察到脂蛋白脂肪酶活性的显着降低。尽管观察到了变化，但暴露于 SD 的西伯利亚仓鼠的体重减轻可能不仅是由于抗脂解能力受损或 SD-脂肪细胞对胰岛素或酪胺的抗脂解反应略有降低。通过将葡萄糖掺入脂质中来测量 WAT 中的基础或胰岛素刺激的脂质积累，在 SD 暴露后没有变化。然而，在 SDanimals 的 WAT 中观察到脂蛋白脂肪酶活性的显着降低。尽管观察到了变化，但暴露于 SD 的西伯利亚仓鼠的体重减轻可能不仅是由于抗脂解能力受损或白色脂肪细胞中的从头脂肪生成活动，但要么来自季节性光周期敏感体重调节期间发生的其他显着变化。