Fish Endocrinology Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
Fish Endocrinology Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
Peptides. 2018 May;103:19-25. doi: 10.1016/j.peptides.2018.03.008. Epub 2018 Mar 13.
The present study demonstrates seasonal variation in the cellular expression of neuropeptide Y (NPY), a known orexigenic neuropeptide, in the testis of the catfish, Clarias batrachus and its relation with testicular steroids. In vitro effects of NPY on androgen production and activities of steroidogenic enzymes were also analyzed to reaffirm the relation between NPY and steroids. NPY-immunoprecipitation was observed in Sertoli cells, interstitial cells and germ cells in recrudescing testis. Intensity of NPY-immunoreaction in the interstitial cells increased steadily with initiation of spermatogenesis and reached maximal in fully grown testes, and then decreased suddenly in the spermiating/spent testis. NPY was also expressed considerably in Sertoli cells in recrudescing testis, but disappeared in the fully grown testis. A moderate NPY-immunoreactivity was also seen in spermatogonial cells in recrudescing testis, but intense NPY-immunoprecipitation was detected in advanced germ cells (spermatids/spermatozoa) in fully mature testis. NPY-immunoreation intensity in interstitial cells showed positive correlation with increasing levels of testicular testosterone and 11-ketotestosterone, and with activities of 3β-HSD & 17β-HSD coinciding with advancing testicular activities. NPY treatment of testicular fragments in vitro stimulated the activities of 3β-HSD & 17β-HSD and increased testosterone & 11-ketotestosterone levels. This study for the first time demonstrates the existence of NPY peptide at cellular levels in fish testis, which stimulates androgen production by acting directly at testicular level.
本研究表明，在鲶鱼（Clarias batrachus）的睾丸中，神经肽 Y（NPY）作为一种已知的食欲肽，其细胞表达存在季节性变化，并且与睾丸类固醇有关。还分析了 NPY 对雄激素产生和类固醇生成酶活性的体外影响，以再次确认 NPY 与类固醇之间的关系。在再生睾丸的精母细胞、间质细胞和生殖细胞中观察到 NPY-免疫沉淀。间质细胞中 NPY-免疫反应的强度随着精子发生的开始而稳步增加，并在完全成熟的睾丸中达到最大值，然后在精子发生/耗尽的睾丸中突然下降。NPY 在再生睾丸的支持细胞中也有相当程度的表达，但在完全成熟的睾丸中消失。在再生睾丸的精原细胞中也观察到中等强度的 NPY-免疫反应，但在完全成熟睾丸的晚期生殖细胞（精母细胞/精子）中检测到强烈的 NPY-免疫沉淀。间质细胞中 NPY-免疫反应的强度与睾丸睾酮和 11-酮睾酮水平的升高呈正相关，与 3β-HSD 和 17β-HSD 的活性呈正相关，而 3β-HSD 和 17β-HSD 的活性与睾丸活动的进展相吻合。NPY 对睾丸组织切片的体外处理刺激了 3β-HSD 和 17β-HSD 的活性，并增加了睾酮和 11-酮睾酮的水平。本研究首次证明了鱼类睾丸中存在 NPY 肽的细胞水平，它通过直接在睾丸水平上起作用刺激雄激素的产生。
