Department of Zoology, Banaras Hindu University, Varanasi 221 005, India.
Gen Comp Endocrinol. 2012 Apr 1;176(2):240-51. doi: 10.1016/j.ygcen.2012.01.020. Epub 2012 Feb 8.
The aim of this study was to evaluate the seasonal variation in serum adiponectin levels and ovarian expression of adiponectin and its receptor in the Scotophilus heathi bat and their relationship to the changes in the body fat mass, serum insulin and luteinizing hormone (LH) levels, and ovarian activity. A very high level of circulating adiponectin was found during recrudescence, whereas a very low level of circulating adiponectin was observed during pre-ovulatory period. The increased circulating adiponectin level coincided with fat deposition, insulin resistance and hyperinsulinemia (HI) in S. heathi. Immunocytochemical study in the ovary of bat showed localization of adiponectin mainly in thecal-interstitial cells (TICs), and adiponectin receptor 1 (AdipoR1) in the granulosa cells of growing follicles, but showed no staining in atretic follicle. Seasonal changes in ovarian adiponectin and AdipoR1 levels showed two peaks (during recrudescence and ovulatory phases) coinciding with two periods of follicular development. Adiponectin in the absence of LH, as occur during recrudescence, stimulates androstenedione (A4) synthesis in vitro by up-regulating the insulin receptor (IR). Adiponectin in presence of LH, as occur during pre-ovulatory phase, inhibits A4 synthesis in vitro by down-regulating androgen receptor (AR). Further, the in vitro study showed that adiponectin, in presence of LH, also promotes luteinizing hormone receptor (LH-R) and steroidogenic acute regulatory protein (StAR) level in the ovary, which might help in development of ovulatory follicles. In brief, adiponectin in the absence of LH induces increased A4 synthesis and consequently the condition of delayed ovulation, whereas in the presence LH suppresses both synthesis and action of A4 and thus induces preovulatory condition in the ovary of S. heathi.
本研究旨在评估血清脂联素水平的季节性变化以及苏格兰管鼻蝠卵巢中脂联素及其受体的表达及其与体脂质量、血清胰岛素和促黄体生成素 (LH) 水平以及卵巢活动的变化之间的关系。在复苏期间发现循环脂联素水平非常高，而在排卵前期间则观察到循环脂联素水平非常低。在 S. heathi 中，循环脂联素水平的升高与脂肪沉积、胰岛素抵抗和高胰岛素血症 (HI) 相吻合。蝙蝠卵巢的免疫细胞化学研究表明，脂联素主要定位于间质-间质细胞 (TICs)，脂联素受体 1 (AdipoR1) 定位于生长卵泡的颗粒细胞，但在闭锁卵泡中无染色。卵巢脂联素和 AdipoR1 水平的季节性变化显示出两个峰值（在复苏和排卵阶段），与两个卵泡发育阶段相对应。在缺乏 LH 的情况下，如在复苏期间，脂联素通过上调胰岛素受体 (IR) 刺激雄烯二酮 (A4) 的合成。在存在 LH 的情况下，如在排卵前阶段，脂联素通过下调雄激素受体 (AR) 抑制体外 A4 的合成。此外，体外研究表明，在存在 LH 的情况下，脂联素还可促进卵巢中黄体生成素受体 (LH-R) 和类固醇急性调节蛋白 (StAR) 的水平，这可能有助于排卵卵泡的发育。简而言之，在缺乏 LH 的情况下，脂联素诱导 A4 合成增加，从而导致排卵延迟，而在存在 LH 的情况下，脂联素抑制 A4 的合成和作用，从而诱导 S. heathi 卵巢的排卵前状态。
