Neuroendocrine mechanism mediating the nutritional infertility

在哺乳动物中，葡萄糖的供应可能是营养不良下生殖功能受到抑制的主要因素之一。在本研究中，葡萄糖供应在调节雌性大鼠促性腺激素释放激素(GnRH)/促性腺激素释放激素(LH)中的作用。检测血糖水平以调节黄体生成素分泌和摄食行为的传感器被认为位于大鼠的下丘脑和延髓。本研究采用Fos免疫组织化学方法对下丘脑室旁核、孤束核和去卵巢大鼠下丘脑后叶(AP)、孤束核(NTS)和下丘脑室旁核Fos蛋白表达进行了研究。Fos和多种细胞标记物如GFAP、MAP-2的双重免疫组织化学显示，AP内表达Fos的细胞可能是神经细胞，而不是神经胶质细胞。这些细胞不是儿茶酚胺能细胞，因为AP内的任何Fos样免疫反应都不与酪氨酸羟基酶免疫反应共存。这些结果表明，AP内的一组非儿茶酚胺能神经元可能参与感知低糖供应，从而调节雌性大鼠的生殖功能和摄食行为。

Glucose availability would be one of the major factors involved in the suppressed reproductive functions under malnutrition in mammalian species. In the present study, the role of glucose availability in regulating gonadotropin-releasing hormone (GnRH)/Iuteinizing hormone (LH) release in female rats. The sensors for detecting the blood glucose level to regulate LH secretion and feeding behavior have been considered to be located in the hypothalamus and medulla oblongata in rats. The present study focussed on the localization of glucose sensors in the area postrema using Fos immunohistochemistry as a marker of neuronal activation.Peripheral administration of a glucose antagonist, 2-deoxyglucose (2DG), induced a massive expression of Fos protein in the area postrema (AP), solitary tract nucleus (NTS) and paraventricular nucleus of the hypothalamus in ovariectomized and estradiol-primed ovariectomized rats. Dual immunohistochemistry with Fos and various cell markers, such as GFAP and MAP-2, showed that Fos-expressing cells in the AP would be neuronal but not glial cells. These cell were not catecholaminergic because any Fos-like immunoreactivities in the AP were not co-localized with tyrosine hydroxy lase immunoreactivity. A part of the Fos-expressing neruons in the NTS was catecholaminergic.These results indicate that a population of non-catecholaminergic neurons in the AP could be involved in sensing low glucose availability to regulate reproductive functions as well as feeding behavior n female rats.