The central role of kisspeptin (kiss) in mammalian reproduction is well established; however, its intra-gonadal role is poorly addressed. Moreover, studies investigating intra-gonadal role of kiss in fish reproduction are scanty, contradictory and inconclusive. The expression of kiss1 mRNA has been detected in the fish brain, and functionally attributed to the regulation of reproduction, feeding and behavior. The kiss1 mRNA has also been demonstrated in tissues other than the brain in some studies, but its cellular distribution and role at the tissue level have not been adequately addressed in fish. Therefore, an attempt was made in the present study to localize kiss1 in gonadal cells of the freshwater catfish, Clarias batrachus. This study reports the presence of kiss1 in the theca cells and granulosa cells of the ovarian oocytes and interstitial cells in the testis of the catfish. The role of kiss1 in the ovary and testis of the catfish was also investigated using kiss1 receptor (kiss1r) antagonist (p234). The p234 treatment decreased the production of 17β-estradiol in ovary and testosterone in the testis by lowering the activities of 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase under both, in vivo as well as in vitro conditions. The p234 treatment also arrested the progression of oogenesis, as evident from the low number of advancing/advanced oocytes in the treated ovary in comparison to the control ovary. It also reduced the area and perimeter of the seminiferous tubules in the treated catfish testis. Thus, our findings suggest that kiss is involved in the regulation of gonadal steroidogenesis, independent of known endocrine/ autocrine/ paracine regulators, and thereby it accelerates gametogenic processes in the freshwater catfish.

Kisspeptin (kiss) 在哺乳动物繁殖中的核心作用已经确立。然而，它在性腺内的作用却没有得到很好的解决。此外，调查亲吻在鱼类繁殖中的性腺内作用的研究很少，相互矛盾且没有定论。已在鱼脑中检测到kiss1 mRNA的表达，其功能归因于繁殖、摄食和行为的调节。在一些研究中， kiss1 mRNA 也已在大脑以外的组织中得到证实，但其在组织水平上的细胞分布和作用尚未在鱼类中得到充分解决。因此，在本研究中尝试将kiss1 定位在淡水鲶鱼Clarias batrachus 的性腺细胞中。这项研究报告了在鲶鱼睾丸中卵巢卵母细胞和间质细胞的卵泡膜细胞和颗粒细胞中存在kiss1。还使用kiss1 受体(kiss1r) 拮抗剂(p234) 研究了kiss1 在鲶鱼卵巢和睾丸中的作用。p234 处理通过降低体内和体外3β-羟基类固醇脱氢酶和 17β-羟基类固醇脱氢酶的活性来减少卵巢中 17β-雌二醇和睾丸中睾酮的产生条件。p234 处理还阻止了卵子发生的进展，这从与对照卵巢相比处理的卵巢中的低数量的推进/先进卵母细胞可以看出。它还减少了处理过的鲶鱼睾丸中曲细精管的面积和周长。因此，我们的研究结果表明，亲吻参与调节性腺类固醇生成，独立于已知的内分泌/自分泌/旁分泌调节剂，从而加速淡水鲶鱼的配子发生过程。