Westberg Lars, Sawa Evelyn, Wang Alice Y, Gunaydin Lisa A, Ribeiro Ana C, Pfaff Donald W
Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10021, USA.
BMC Neurosci. 2009 Apr 30;10:41. doi: 10.1186/1471-2202-10-41.
Gap junction proteins, connexins, are expressed in most endocrine and exocrine glands in the body and are at least in some glands crucial for the hormonal secretion. To what extent connexins are expressed in neurons releasing hormones or neuropeptides from or within the central nervous system is, however, unknown. Previous studies provide indirect evidence for gap junction coupling between subsets of neuropeptide-containing neurons in the paraventricular nucleus (PVN) of the hypothalamus. Here we employ double labeling and retrograde tracing methods to investigate to what extent neuroendocrine and neuropeptide-containing neurons of the hypothalamus and brainstem express the neuronal gap junction protein connexin 36.
Western blot analysis showed that connexin 36 is expressed in the PVN. In bacterial artificial chromosome transgenic mice, which specifically express the reporter gene Enhanced Green Fluorescent Protein (EGFP) under the control of the connexin 36 gene promoter, EGFP expression was detected in magnocellular (neuroendocrine) and in parvocellular neurons of the PVN. Although no EGFP/connexin36 expression was seen in neurons containing oxytocin or vasopressin, EGFP/connexin36 was found in subsets of PVN neurons containing corticotropin-releasing hormone (CRH), and in somatostatin neurons located along the third ventricle. Moreover, CRH neurons in brainstem areas, including the lateral parabrachial nucleus, also expressed EGFP/connexin 36.
Our data indicate that connexin 36 is expressed in subsets of neuroendocrine and CRH neurons in specific nuclei of the hypothalamus and brainstem.
缝隙连接蛋白，即连接蛋白，在身体的大多数内分泌和外分泌腺中均有表达，并且至少在某些腺体中对于激素分泌至关重要。然而，连接蛋白在从中枢神经系统释放激素或神经肽的神经元中的表达程度尚不清楚。先前的研究为下丘脑室旁核（PVN）中含神经肽的神经元亚群之间的缝隙连接耦合提供了间接证据。在此，我们采用双重标记和逆行追踪方法，以研究下丘脑和脑干中神经内分泌和含神经肽的神经元在多大程度上表达神经元缝隙连接蛋白连接蛋白36。
蛋白质免疫印迹分析表明连接蛋白36在室旁核中表达。在细菌人工染色体转基因小鼠中，其在连接蛋白36基因启动子的控制下特异性表达报告基因增强型绿色荧光蛋白（EGFP），在室旁核的大细胞（神经内分泌）和小细胞神经元中检测到EGFP表达。虽然在含有催产素或加压素的神经元中未观察到EGFP/连接蛋白36表达，但在含有促肾上腺皮质激素释放激素（CRH）的室旁核神经元亚群以及位于第三脑室沿线的生长抑素神经元中发现了EGFP/连接蛋白36。此外，脑干区域包括外侧臂旁核中的CRH神经元也表达EGFP/连接蛋白36。
我们的数据表明连接蛋白36在下丘脑和脑干特定核团的神经内分泌和CRH神经元亚群中表达。
