Kummrow Maya S, Roig-Genovés Jose V, Giménez Ignacio, Tzika Athanasia C, Clauss Marcus, Neuhauss Stephan C F, Hatt Jean-Michel, Gesemann Matthias
Clinic for Zoo Animals, Exotic Pets and Wildlife, Department for Small Animals, University of Zurich, Zurich 8057, Switzerland.
Rara Avis Biotec, Valencia 46002, Spain.
Endocrinology. 2025 Jul 8;166(9). doi: 10.1210/endocr/bqaf128.
Vertebrate reproduction is controlled by 2 pituitary gonadotropin hormones (GtHs), FSH and LH, binding to gonadotropin hormone receptors (GtHRs) in gonadal tissues. All gnathostome vertebrates have been confirmed to possess at least 1 receptor for each GtH [LH receptor (LHR) and FSH receptor (FSHR)], except for species of the reptilian (nonavian sauropsidan) orders, such as lepidosauria, testudines, and crocodylia, which showed inexplicable reactions to heterologous amphibian, avian, and mammalian GtHs in early endocrinological studies. This study investigated the number and function of reptilian GtHRs. Genomic and transcriptomic analyses of selected tetrapod species now strongly suggest the inactivation of the LHR in all nonavian sauropsidans. This gene inactivation likely occurred independently in 3 branches of the sauropdisan clade, sparing only the avian class. Bioassays served to investigate the binding specificity of squamate, chelonian, crocodilian, avian, and mammalian GtHRs with their homologous and heterologous GtHs. The FSHR of a squamate lizard proved completely promiscuous to both its homologous GtHs, while the chelonian FSHR responded slightly stronger to the homologous LH than FSH, and the crocodylian FSHR was only stimulated by the homologous LH but not FSH. We therefore propose a modified paradigm with a neuroendocrine control of nonavian reptilian reproduction by a single GtHR and either 1 GtH in crocodylians or 2 GtHs in chelonians and squamate reptiles. Finally, we discuss hypotheses of tightly regulated temporal and spatial expression of the remaining FSHR in different gonadal somatic cells and temperature-dependent functions of the single nonavian reptilian GtHR.
脊椎动物的繁殖受两种垂体促性腺激素（促性腺激素，GtHs），即促卵泡激素（FSH）和促黄体生成素（LH）控制，它们与性腺组织中的促性腺激素受体（GtHRs）结合。除了爬行类（非鸟类蜥形纲）目，如蜥蜴目、龟鳖目和鳄目，所有有颌脊椎动物都已被证实每种促性腺激素至少拥有一种受体[促黄体生成素受体（LHR）和促卵泡激素受体（FSHR）]，在早期内分泌学研究中，这些爬行类动物对异源两栖类、鸟类和哺乳类促性腺激素表现出无法解释的反应。本研究调查了爬行类促性腺激素受体的数量和功能。对选定四足动物物种的基因组和转录组分析现在强烈表明，所有非鸟类蜥形纲动物的促黄体生成素受体均已失活。这种基因失活可能在蜥形纲进化枝的三个分支中独立发生，仅鸟类得以幸免。生物测定用于研究有鳞目、龟鳖目、鳄目、鸟类和哺乳类促性腺激素受体与其同源和异源促性腺激素的结合特异性。一种有鳞目蜥蜴的促卵泡激素受体被证明对其同源促性腺激素完全没有特异性，而龟鳖目的促卵泡激素受体对同源促黄体生成素的反应比对促卵泡激素略强，鳄目的促卵泡激素受体仅受同源促黄体生成素刺激，不受促卵泡激素刺激。因此，我们提出了一种修正的模式，即非鸟类爬行动物的繁殖由单一促性腺激素受体进行神经内分泌控制，在鳄目中由一种促性腺激素控制，在龟鳖目和有鳞目爬行动物中由两种促性腺激素控制。最后，我们讨论了关于剩余促卵泡激素受体在不同性腺体细胞中受到严格调控的时空表达以及单一非鸟类爬行动物促性腺激素受体的温度依赖性功能的假说。
