Department of Genetics and Marine Biotechnology, Institute of Oceanology of Polish Academy of Sciences, Powstańców Warszawy 55, 81-712 Sopot, Poland
Department of Genetics and Marine Biotechnology, Institute of Oceanology of Polish Academy of Sciences, Powstańców Warszawy 55, 81-712 Sopot, Poland.
Biol Open. 2014 Dec 19;4(1):69-78. doi: 10.1242/bio.20149597.
Fish may respond to different social situations with changes in both physiology and behaviour. A unique feature of fish is that social interactions between males and females strongly affect the sexual characteristics of individuals. Here we provide the first insight into the endocrine background of two phenomena that occur in mono-sex groups of the black molly (Poecilia sphenops): masculinization in females and same-sex sexual behaviour, manifested by gonopodial displays towards same-sex tank mates and copulation attempts in males. In socially controlled situations, brain neurohormones impact phenotypic sex determination and sexual behaviour. Among these hormones are the nonapeptides arginine vasotocin (AVT) and isotocin (IT), counterparts of the well-known mammalian arginine vasopressin and oxytocin, respectively. To reveal potential hormone interactions, we measured the concentrations of bioactive AVT and IT in the brain, along with those of the sex steroids 17β-estradiol and 11-ketotestosterone in the gonads, of females, masculinized females, males displaying same-sex sexual behaviour and those who did not. These data were supplemented by morphological and histological analyses of the gonads. Correlations between brain nonapeptides and gonadal steroids strongly suggest a cross talk between hormonal systems. In the black molly, the masculinization process was associated with the production of brain AVT and gonadal steroids, whereas same-sex sexual behaviour involves both brain nonapeptides, but neither of the sex steroids. This study extends current knowledge of endocrine control of phenotypic sex and sexual behaviour in fish and for the first time links brain nonapeptides with the occurrence of male-male sexual behaviour in lower vertebrates.
鱼类可能会通过生理和行为的变化来应对不同的社交情况。鱼类的一个独特特征是，雄性和雌性之间的社交互动会强烈影响个体的性特征。在这里，我们首次深入了解了黑摩利鱼（Poecilia sphenops）单性群体中发生的两种现象的内分泌背景：雌性的雄性化和同性性行为，表现为对同性水箱同伴的生殖肢展示和雄性的交配尝试。在受社会控制的情况下，脑神经激素会影响表型性别决定和性行为。这些激素包括非肽类血管加压素（AVT）和催产素（IT），分别是众所周知的哺乳动物血管加压素和催产素的对应物。为了揭示潜在的激素相互作用，我们测量了大脑中生物活性 AVT 和 IT 的浓度，以及性腺中类固醇 17β-雌二醇和 11-酮睾酮的浓度，这些是雌性、雄性化雌性、表现同性性行为的雄性和不表现同性性行为的雄性。这些数据通过对性腺的形态和组织学分析得到补充。脑神经肽和性腺类固醇之间的相关性强烈表明激素系统之间存在交叉对话。在黑摩利鱼中，雄性化过程与大脑 AVT 和性腺类固醇的产生有关，而同性性行为则涉及脑神经肽，但不涉及任何一种性激素。这项研究扩展了鱼类中表型性别和性行为的内分泌控制的现有知识，并首次将脑神经肽与低等脊椎动物中雄性间性行为的发生联系起来。
