In this investigation, we examined the influence of alpha-melanocyte stimulating hormone (α-MSH), a proopiomelanocortin-derived peptide, along the hypothalamic-pituitary-gonad axis in a cichlid fish Oreochromis mossambicus. Administration of α-MSH (40 µg/0.1 ml saline) for 22 days did not affect the number of stage I (previtellogenic) follicles but caused significant reduction in the mean numbers of previtellogenic (stages II and III), vitellogenic (stage IV) and preovulatory (stage V) follicles compared to those of controls. While the gonadosomatic index was significantly lower, the rate of follicular atresia in stages II, III and IV remained significantly higher in α-MSH-treated fish compared to the controls. Furthermore, the mean percent area of gonadotropin-releasing hormone-immunoreactive (GnRH-ir) fibres and luteinizing hormone-immunoreactive (LH-ir) cells were significantly reduced in the proximal pars distalis of the pituitary gland in α-MSH-treated fish compared with the controls. Together, our findings suggest for the first time that the treatment of α-MSH blocks the follicular developmental process during the ovarian cycle, possibly through the inhibition of GnRH-LH pathway in teleosts.

在这项调查中，我们研究了 α-促黑素细胞激素 (α-MSH)，一种阿黑皮素原衍生肽，沿着慈鲷鱼Oreochromis mossambicus的下丘脑-垂体-性腺轴的影响. 使用 α-MSH（40 µg/0.1 ml 生理盐水）22 天不会影响 I 期（卵黄前）卵泡的数量，但导致卵黄前（II 期和 III 期）、卵黄期（IV 期）的平均数量显着减少与对照组相比，排卵前（V 期）卵泡。虽然性腺指数显着降低，但与对照组相比，α-MSH 处理的鱼在 II、III 和 IV 阶段的卵泡闭锁率仍然显着更高。此外，与 α-MSH 处理的鱼相比，在垂体近端远端部分的促性腺激素释放激素免疫反应 (GnRH-ir) 纤维和黄体生成素免疫反应 (LH-ir) 细胞的平均百分比面积显着减少与控件。一起，