Gonadotropin-inhibitory hormone (GnIH) is a newly discovered hypothalamic RFamide peptide that influences reproduction by regulating brain and pituitary neuroendocrine functions in vertebrates. We report here for the first time, the ontogenetic description of GnIH-like immunoreactivity in the brain, olfactory system, and pituitary of the frog, Pelophylax esculentus. GnIH-like immunoreactive (GnIH-ir) elements were first observed in larvae at stage 24 in the olfactory mucosa, ventral telencephalon, and diencephalon. GnIH-ir-positive staining progressively increased in frequency and intensity during larval growth and other ir perikarya appeared in the medial septum, anterior commissure, dorsal hypothalamus, and posterior tuberculum. A decline in GnIH-ir neurons was seen along the olfactory/vomeronasal/terminal nerve complex in the stages following the pre- and prometamorphosis, while other GnIH-ir neurons showed positivity in the ventromedial surface of the olfactory bulbs and into the habenular nuclei, but the latter are no longer observed in the following stages of development. The anterior-posterior axis in several brain areas, along with the median eminence and pars intermedia of the hypophysis had the appearance of GnIH-ir fibers from early stages, with a progressive increase in the number till metamorphosis in all major subdivisions of the brain. After premetamorphosis, GnIH-ir fibers arising from labeled neurons in the suprachiasmatic nucleus could be seen contacting the ventricular lumen. The transient appearance of GnIH-ir elements in the olfactory system may hint at an olfactory placode origin in the extracranial region. The distribution of GnIH in several brain regions throughout development suggests important involvement of GnIH in multiple brain functions during development.

中文翻译：

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发育过程中青蛙 (Pelophylax esculentus) 大脑和垂体中促性腺激素抑制激素 (GnIH) 样免疫反应性的分布

促性腺激素抑制激素 (GnIH) 是一种新发现的下丘脑 RFamide 肽，通过调节脊椎动物的大脑和垂体神经内分泌功能影响生殖。我们在这里首次报告了青蛙 Pelophylax esculentus 的大脑、嗅觉系统和垂体中 GnIH 样免疫反应性的个体发生学描述。GnIH 样免疫反应 (GnIH-ir) 元件首先在第 24 阶段的嗅粘膜、腹侧端脑和间脑中的幼虫中观察到。GnIH-ir 阳性染色在幼虫生长过程中的频率和强度逐渐增加，其他 ir perikarya 出现在内侧隔、前连合、背侧下丘脑和后结节。在前变态和前变态后的阶段，沿着嗅/犁鼻/末梢神经复合体观察到 GnIH-ir 神经元的下降，而其他 GnIH-ir 神经元在嗅球的腹内侧表面和缰核中显示阳性，但在以下发展阶段不再观察到后者。几个脑区的前后轴，以及垂体的正中隆起和中间部分从早期就出现了 GnIH-ir 纤维，数量逐渐增加，直到脑的所有主要细分都发生变形。在变态前，可以看到来自视交叉上核中标记神经元的 GnIH-ir 纤维与心室腔接触。GnIH-ir 元素在嗅觉系统中的短暂出现可能暗示颅外区域的嗅觉基板起源。GnIH 在整个发育过程中几个大脑区域的分布表明 GnIH 在发育过程中对多种大脑功能的重要参与。