Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda University, Shinjuku-ku, Tokyo, Japan.
Laboratory of Animal Genetics and Breeding, Department of Animal Science and Biotechnology, School of Veterinary Medicine, Azabu University, Chuo-ku, Sagamihara, Kanagawa, Japan.
J Neuroendocrinol. 2017 Aug;29(8). doi: 10.1111/jne.12503.
Gonadotrophin-inhibitory hormone (GnIH) is a hypothalamic neuropeptide that inhibits gonadotrophin synthesis and release in birds and mammals. In Japanese quail, GnIH neurones express the noradrenergic receptor and receive noradrenergic innervation. Treatment with noradrenaline (NA) stimulates GnIH release from diencephalic tissue blocks in vitro. However, the effects of NA on hypothalamic GnIH gene expression have not been determined. We investigated noradrenergic regulation of GnIH gene expression in the brain of male quail using the selective noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride (DSP-4). We first showed that DSP-4 reduced the number of noradrenergic (dopamine-β-hydroxylase immunoreactive) cells in the locus coeruleus (LoC) and specifically lowered the NA concentration in the hypothalamus of male quail. Other monoamines, such as dopamine and serotonin, were not affected by drug treatment. DSP-4 did not decrease the numbers of noradrenergic cells of the lateral tegmental cell group, nor the plasma NA concentration. Decreased hypothalamic NA levels after DSP-4 treatment did not change GnIH gene expression in the brains of quail during their interaction with conspecifics. On the other hand, GnIH gene expression increased in the brains of quail socially isolated for 1 hour after DSP-4 treatment. These results suggest that some noradrenergic neurones have inhibitory effects on GnIH gene expression of the hypothalamus in solitary quail.
促性腺激素抑制激素（GnIH）是一种下丘脑神经肽，它抑制鸟类和哺乳动物的促性腺激素合成和释放。在日本鹌鹑中，GnIH 神经元表达去甲肾上腺素能受体并接受去甲肾上腺素能神经支配。用去甲肾上腺素（NA）处理可刺激体外脑片组织中 GnIH 的释放。然而，NA 对下丘脑 GnIH 基因表达的影响尚未确定。我们使用选择性去甲肾上腺素能神经毒素 N-（2-氯乙基）-N-乙基-2-溴苯甲胺盐酸盐（DSP-4）研究了雄性鹌鹑大脑中去甲肾上腺素能对 GnIH 基因表达的调节。我们首先表明，DSP-4 减少了蓝斑（LC）中的去甲肾上腺素能（多巴胺-β-羟化酶免疫反应性）细胞数量，并特异性降低了雄性鹌鹑下丘脑的 NA 浓度。其他单胺类物质，如多巴胺和 5-羟色胺，不受药物治疗的影响。DSP-4 不会减少外侧脑桥细胞群中的去甲肾上腺素能细胞数量，也不会降低血浆 NA 浓度。DSP-4 处理后下丘脑 NA 水平降低，不会改变与同种鹌鹑相互作用时鹌鹑大脑中的 GnIH 基因表达。另一方面，DSP-4 处理后，鹌鹑在社交隔离 1 小时后大脑中的 GnIH 基因表达增加。这些结果表明，一些去甲肾上腺素能神经元对独居鹌鹑下丘脑 GnIH 基因表达具有抑制作用。
