The present study aimed to evaluate osmotic pump-mediated controlled release of estrogen in males and androgen in females to analyze the impact on gonadotropin-releasing hormone (GnRH1), catecholamines (CAs) and other associated genes in the catfish, Clarias gariepinus. During pre-spawning phase, catfish were separately implanted osmotic pumps loaded with 17β-estradiol (E₂) in males and 17α-methyltestosterone (MT) in females at a dose of 10 μg/100 μl or saline (100 μl) controls into both sexes to release for 21 days and all fishes were maintained as per the duration. Further, GnRH1 expression levels were analysed in the discrete regions of brain after E₂ and MT treatments in male and female catfish, respectively using qPCR which revealed that GnRH1 expression was significantly higher in E₂ treated male as compared to the control. On the other hand, GnRH1 expression was lower in MT treated female when compared to the control in the discrete regions of brain. In addition, certain brain and monoaminergic system related genes showed a differential response. Catfish GnRH1 could be localized in preoptic area-hypothalamus (POA-HYP) that correlated with the expression profile in the discrete regions of catfish brain. Serum levels of sex steroids in the treated male fish indicated that the treatment of E₂ could maintain and impart feminization effect even in the presence of endogenous androgen during gonadal recrudescence while such an effect was not seen in females with androgen treatment. Measurement of CAs, L-3,4-dihydroxyphenylalanine, dopamine and norepinephrine levels in the male and female brain after the controlled release of E₂ and MT, respectively confirmed the modulation of neurotransmitters in the E₂treated male than MT treated female fish. These results collectively suggest the severity of estrogenic over androgenic compounds to alter reproductive status even at a minimal dose by targeting CAs and GnRH1 at the level of brain of catfish. This study provides insights into the reproductive toxicity of sex steroid analogues at the level of brain GnRH1 and CA-ergic system in addition to serum T, 11-KT and E₂ levels during gonadal recrudescence, which is a crucial period of gametogenesis preceding spawning.

本研究旨在评估渗透泵介导的雄性雌激素和雌性雄激素的控制释放，以分析对鲶鱼Clarias gariepinus促性腺激素释放激素 (GnRH1)、儿茶酚胺 (CA) 和其他相关基因的影响。在产卵前阶段，鲶鱼分别植入装有 17β-雌二醇 (E ₂ ) 的雄性和雌性 17α-甲基睾酮 (MT) 的渗透泵，剂量为 10 μg/100 μl 或生理盐水 (100 μl) 对照。雌雄放归 21 天，所有鱼类均按期限保持。此外，在 E ₂后分析了脑的离散区域中的 GnRH1 表达水平和 MT 处理分别使用 qPCR 显示雄性和雌性鲶鱼的 GnRH1 表达在 E ₂处理的雄性中显着高于对照。另一方面，与大脑离散区域中的对照相比，MT 治疗的女性中 GnRH1 的表达较低。此外，某些脑和单胺能系统相关基因表现出不同的反应。鲶鱼 GnRH1 可以定位于视前区-下丘脑 (POA-HYP)，这与鲶鱼大脑离散区域的表达谱相关。处理过的雄性鱼的血清性类固醇水平表明 E ₂的处理即使在性腺复发期间存在内源性雄激素，也可以维持和赋予女性化效果，而在接受雄激素治疗的女性中未观察到这种效果。在控制释放 E ₂和 MT 后，分别测量男性和女性大脑中的 CA、L-3,4-二羟基苯丙氨酸、多巴胺和去甲肾上腺素水平，证实了 E ₂中神经递质的调节处理过的雄鱼多于 MT 处理过的雌鱼。这些结果共同表明雌激素比雄激素化合物更严重，即使在最小剂量下，通过靶向鲶鱼脑水平的 CA 和 GnRH1 也能改变生殖状态。这项研究提供了对性类固醇类似物在脑 GnRH1 和 CA 能系统水平以及性腺复发期间血清 T、11-KT 和 E ₂水平的生殖毒性的见解，这是产卵前配子发生的关键时期。