Leenders H J, Janssens J J, Theunissen H J, Jenks B G, van Overbeeke A P
Neuroendocrinology. 1986;43(2):166-74. doi: 10.1159/000124524.
This report concerns ontogenetic aspects of the production and in vitro release of NH2-terminally acetylated forms of melanocyte-stimulating hormone (alpha-MSH) and beta-endorphin by the pars intermedia of the pituitary gland of the mouse. In vitro biosynthetic analysis and radioimmunoassay revealed that approximately 12 h before birth most of the MSH in the fetal pars intermedia is present as des-N alpha-acetyl alpha-MSH. The same non-acetylated peptide is at this stage also the major release form of melanotropin. In 1-day-old mice the level of alpha-MSH and diacetylated alpha-MSH had increased considerably, although des-N alpha-acetyl alpha-MSH remained the major form. Five days after birth alpha-MSH and its diacetylated form constitute the major tissue and release form of the peptide, a situation very similar to that in adult mice. Acetylation of beta-endorphin appeared to occur earlier in development, N alpha-acetyl beta-endorphin (1-31) being the major form of endorphin already in the fetal pars intermedia. It is concluded that in the mouse acetylation of melanotropin and acetylation of beta-endorphin are not necessarily concomitant events. It could be established that the ability of the pars intermedia cells for cleaving N alpha-acetyl beta-endorphin (1-31) to yield C-terminally shortened forms of beta-endorphin develops after birth.
本报告涉及小鼠垂体中间部产生及体外释放N端乙酰化形式的促黑素细胞激素（α-MSH）和β-内啡肽的个体发生方面。体外生物合成分析和放射免疫测定显示，在出生前约12小时，胎儿垂体中间部的大部分MSH以去Nα-乙酰化α-MSH的形式存在。在这个阶段，相同的非乙酰化肽也是促黑素的主要释放形式。在1日龄小鼠中，α-MSH和双乙酰化α-MSH的水平显著增加，尽管去Nα-乙酰化α-MSH仍然是主要形式。出生后5天，α-MSH及其双乙酰化形式构成了该肽的主要组织和释放形式，这种情况与成年小鼠非常相似。β-内啡肽的乙酰化似乎在发育过程中更早发生，Nα-乙酰化β-内啡肽（1-31）已经是胎儿垂体中间部内啡肽的主要形式。结论是，在小鼠中，促黑素的乙酰化和β-内啡肽的乙酰化不一定是同时发生的事件。可以确定，垂体中间部细胞将Nα-乙酰化β-内啡肽（1-31）裂解产生C端缩短形式的β-内啡肽的能力在出生后才发育。
