Dores R M, Jain M, Akil H
Brain Res. 1986 Jul 9;377(2):251-60. doi: 10.1016/0006-8993(86)90866-8.
The post-translational processing of pro-opiomelanocortin (POMC) in brain remains controversial. Classically, there was thought to be a single cell group in the arcuate nucleus with long projections through limbic structures. More recently, a second cell group was discovered in the caudal medulla. This study addresses the question of POMC processing in this region. Steady-state analysis of acid extracts of dorsal caudal medulla from rat and guinea pig CNS by gel filtration chromatography and radioimmunoassay indicated that in both species the major POMC-related end products are alpha-MSH-sized material and beta-endorphin-sized. In this tissue beta-LPH and ACTH represent minor end products. Analysis of the alpha-MSH-sized material from both species by reverse-phase HPLC indicated that in the rat caudal medulla approximately 79% of the alpha-MSH-related material is acetylated, and in the guinea pig caudal medulla approximately 85% of the alpha-MSH-related material is acetylated. Analysis of the forms of beta-endorphin isolated from the rat caudal medulla by cation exchange chromatography revealed that acetylated and non-acetylated forms of beta-endorphin are present in this region of the rat CNS. Approximately 65% of the beta-endorphin in the rat caudal medulla is N-acetylated. Analysis of the forms of beta-endorphin isolated from the guinea pig caudal medulla indicated that approximately 63% of the beta-endorphin is N-acetylated in this region of the guinea pig CNS. These data indicate that the post-translational processing of POMC in the dorsal caudal medulla, the site of the nucleus tractus solitarius POMC cell group, is distinct from the processing patterns that have been reported for POMC systems in the mammalian anterior pituitary, intermediate pituitary and arcuate nucleus.
脑内阿片-促黑素原（POMC）的翻译后加工仍存在争议。传统观点认为，弓状核中有一个单细胞群，其长投射穿过边缘结构。最近，在延髓尾部发现了第二个细胞群。本研究探讨了该区域POMC的加工问题。通过凝胶过滤色谱法和放射免疫分析法对大鼠和豚鼠中枢神经系统尾侧延髓背侧酸提取物进行稳态分析表明，在这两个物种中，主要的POMC相关终产物是α-促黑素细胞激素（α-MSH）大小的物质和β-内啡肽大小的物质。在该组织中，β-促脂素（β-LPH）和促肾上腺皮质激素（ACTH）是次要终产物。通过反相高效液相色谱法对这两个物种的α-MSH大小的物质进行分析表明，在大鼠尾侧延髓中，约79%的α-MSH相关物质被乙酰化，而在豚鼠尾侧延髓中，约85%的α-MSH相关物质被乙酰化。通过阳离子交换色谱法对从大鼠尾侧延髓分离出的β-内啡肽形式进行分析发现，大鼠中枢神经系统的该区域存在乙酰化和非乙酰化形式的β-内啡肽。大鼠尾侧延髓中约65%的β-内啡肽是N-乙酰化的。对从豚鼠尾侧延髓分离出的β-内啡肽形式进行分析表明，在豚鼠中枢神经系统的该区域中，约63%的β-内啡肽是N-乙酰化的。这些数据表明，孤束核POMC细胞群所在的尾侧延髓背侧POMC的翻译后加工，与哺乳动物垂体前叶、垂体中间叶和弓状核中POMC系统所报道的加工模式不同。
