Hervieu G, Nahon J L
Institut de Pharmacologie Moléculaire et Cellulaire, UPR 411 CNRS, Université de Nice Sophia Antipolis, Valbonne, France.
Neuroendocrinology. 1995 Apr;61(4):348-64. doi: 10.1159/000126857.
Melanin-concentrating hormone (MCH) is a cyclic peptide which is predominantly synthetized in the hypothalamus of fish and mammalian brains. In the present paper we examined the expression of MCH mRNA and pro-MCH-derived peptides, i.e. MCH and neuropeptide-(N)-glutamic acid (E) isoleucine (I) amide (NEI), in peripheral tissues of adult rodents. By means of polymerase chain reaction (PCR) of reverse-transcribed RNA, low levels of MCH gene transcripts were detected reliably in testis, stomach, and intestine of Sprague-Dawley and Wistar rats, whereas strong expression was found in hypothalamus. Subsequent sequence analysis of the PCR products verified the authenticity of MCH mRNA found in hypothalamus and stomach. The length of MCH RNA species was measured by Northern blot and multiple MCH RNA species were detected in both rat species. Shortest polyadenylated tails were found in MCH RNAs isolated from the peripheral organs by comparison with hypothalamus MCH RNAs of Wistar rats. In order to localize MCH expression in gastrointestinal and genital tracts of Wistar rats we performed in situ hybridization with specific 33P-labeled oligoprobes joined to immunocytochemical studies with rat MCH or NEI antisera. In testis, the MCH transcripts and pro-MCH-derived peptide immunoreactivities were found at the periphery of the seminiferous tubules, suggesting expression in Sertoli cells. Studies with MCH oligoprobes and antisera directed towards MCH, NEI and alpha A-inhibin revealed similar pattern of expression in isolated Sertoli cells from Swiss mice, indicating that MCH RNA species were actually synthesized and translated in these cells. In the gastrointestinal (GI) tract, the cells expressing MCH RNA species and pro-MCH-derived peptides were predominantly expressed in the antral portion of the stomach and duodenum. Strikingly, distinct oligoprobes, recognizing antisense MCH transcript, revealed a pattern of hybridization in the GI tract similar to this observed with oligoprobes revealing the mature MCH mRNA. Furthermore, total RNA from the pyloric junction, duodenum, jejunum, ileum and hypothalamus as well appeared to contain RNA complementary to MCH mRNA suggesting therefore that antisense MCH RNA species may play a general role in regulation of MCH synthesis. Taken together, our present and previous data indicate that authentic MCH RNA species and translational products are expressed in various rodent tissues at the periphery. The cellular location suggests that MCH and associated peptides may play a role in spermatogenesis and in digestive processes.
黑色素聚集激素（MCH）是一种环肽，主要在鱼类和哺乳动物大脑的下丘脑合成。在本文中，我们检测了成年啮齿动物外周组织中MCH mRNA和前体MCH衍生肽，即MCH和神经肽 -（N）-谷氨酸（E）异亮氨酸（I）酰胺（NEI）的表达。通过逆转录RNA的聚合酶链反应（PCR），在Sprague-Dawley大鼠和Wistar大鼠的睾丸、胃和肠道中可靠地检测到低水平的MCH基因转录本，而下丘脑则有强表达。随后对PCR产物的序列分析证实了在下丘脑和胃中发现的MCH mRNA的真实性。通过Northern印迹法测量MCH RNA种类的长度，在两种大鼠中均检测到多种MCH RNA种类。与Wistar大鼠下丘脑的MCH RNA相比，从外周器官分离的MCH RNA中发现了最短的聚腺苷酸尾巴。为了定位Wistar大鼠胃肠道和生殖道中的MCH表达，我们用特异性33P标记的寡核苷酸探针进行原位杂交，并结合大鼠MCH或NEI抗血清进行免疫细胞化学研究。在睾丸中，MCH转录本和前体MCH衍生肽免疫反应性出现在生精小管的周边，提示在支持细胞中表达。用针对MCH、NEI和αA抑制素的MCH寡核苷酸探针和抗血清进行的研究表明，在瑞士小鼠分离的支持细胞中有相似的表达模式，表明MCH RNA种类实际上在这些细胞中合成和翻译。在胃肠道（GI）中，表达MCH RNA种类和前体MCH衍生肽的细胞主要在胃窦部和十二指肠中表达。引人注目的是，识别反义MCH转录本的不同寡核苷酸探针在胃肠道中显示出与揭示成熟MCH mRNA的寡核苷酸探针相似的杂交模式。此外，来自幽门连接处、十二指肠、空肠、回肠和下丘脑的总RNA似乎也含有与MCH mRNA互补的RNA，因此表明反义MCH RNA种类可能在MCH合成的调节中起普遍作用。综上所述，我们目前和以前的数据表明，真正的MCH RNA种类和翻译产物在周边的各种啮齿动物组织中表达。细胞定位表明，MCH和相关肽可能在精子发生和消化过程中起作用。
