Navarro Sandra, Crespo Diego, Schulz Rüdiger W, Ge Wei, Rotllant Josep, Cerdá-Reverter José Miguel, Rocha Ana
Centro de Investigación en Recursos Naturales y Sustentabilidad (CIRENYS), Universidad Bernardo O'Higgins, Avenida Viel 1497, Santiago 8370993, Chile.
Reproduction and Developmental Biology Group, Institute of Marine Research, NO-5817 Bergen, Norway.
Animals (Basel). 2022 Oct 12;12(20):2737. doi: 10.3390/ani12202737.
In teleost, as in other vertebrates, stress affects reproduction. A key component of the stress response is the pituitary secretion of the adrenocorticotropic hormone (ACTH), which binds to the melanocortin 2 receptor (MC2R) in the adrenal glands and activates cortisol biosynthesis. In zebrafish, Mc2r was identified in male and female gonads, while ACTH has been shown to have a physiological role in modulating reproductive activity. In this study, the hypothesis that other melanocortins may also affect how the zebrafish gonadal function is explored, specifically steroid biosynthesis, given the presence of members of the melanocortin signaling system in zebrafish gonads. Using cell culture, expression analysis, and cellular localization of gene expression, our new observations demonstrated that melanocortin receptors, accessory proteins, antagonists, and agonists are expressed in both the ovary and testis of zebrafish ( = 4 each sex). Moreover, melanocortin peptides modulate both basal and gonadotropin-stimulated steroid release from zebrafish gonads ( = 15 for males and = 50 for females). In situ hybridization in ovaries ( = 3) of zebrafish showed and in follicular cells and adjacent to cortical alveoli in the ooplasm of previtellogenic and vitellogenic oocytes. In zebrafish testes ( = 3), and were detected exclusively in germ cells, specifically in spermatogonia and spermatocytes. Our results suggest that melanocortins are, directly or indirectly, involved in the endocrine control of vitellogenesis in females, through modulation of estradiol synthesis via autocrine or paracrine actions in zebrafish ovaries. Adult zebrafish testes were sensitive to low doses of ACTH, eliciting testosterone production, which indicates a potential role of this peptide as a paracrine regulator of testicular function.
与其他脊椎动物一样，硬骨鱼的应激反应会影响其繁殖。应激反应的一个关键组成部分是垂体分泌促肾上腺皮质激素（ACTH），它与肾上腺中的黑皮质素2受体（MC2R）结合并激活皮质醇的生物合成。在斑马鱼中，已在雄性和雌性性腺中鉴定出Mc2r，而ACTH已被证明在调节生殖活动中具有生理作用。鉴于斑马鱼性腺中存在黑皮质素信号系统的成员，本研究探讨了其他黑皮质素可能也会影响斑马鱼性腺功能（特别是类固醇生物合成）的假说。通过细胞培养、表达分析和基因表达的细胞定位，我们的新观察结果表明，黑皮质素受体、辅助蛋白、拮抗剂和激动剂在斑马鱼的卵巢和睾丸中均有表达（每种性别各n = 4）。此外，黑皮质素肽可调节斑马鱼性腺基础和促性腺激素刺激的类固醇释放（雄性n = 15，雌性n = 50）。斑马鱼卵巢（n = 3）的原位杂交显示，在卵泡细胞以及卵黄生成前和卵黄生成期卵母细胞卵质中与皮质泡相邻处有[具体物质1]和[具体物质2]。在斑马鱼睾丸（n = 3）中，[具体物质1]和[具体物质2]仅在生殖细胞中检测到，特别是在精原细胞和精母细胞中。我们的结果表明，黑皮质素通过在斑马鱼卵巢中通过自分泌或旁分泌作用调节雌二醇合成，直接或间接地参与雌性卵黄生成的内分泌控制。成年斑马鱼睾丸对低剂量的ACTH敏感，可引发睾酮生成，这表明该肽作为睾丸功能旁分泌调节因子的潜在作用。
