Facchinetti F, Genazzani A R, Pestarino M, Vallarino M, Pierantoni R, Fasano S, D'Antonio M, Carnevali O, Mosconi G, Polzonetti-Magni A
Dept. of Obstetrics and Gynecology, University of Modena, Italy.
Life Sci. 1992;50(19):1389-98. doi: 10.1016/0024-3205(92)90257-p.
In mammals, proopiomelanocortin-related peptides are involved in reproductive processes both at the hypothalamo-pituitary and ovarian levels. Using immunocytochemical, biochemical and physiological "in vitro" studies, we provide here evidence for a diffuse POMC-related opioid system in the frog Rana esculenta. Ovarian beta-endorphin (beta-EP) is expressed in thecal cells and changes during the reproductive cycle in an inverse relationship with follicular development. Seasonal changes in the ovary are different to those in the brain or in the pituitary. The ratio of acetylated vs native beta-EP in the ovary also changes over the reproductive period, affecting the biological activity of the peptide. During both the reproductive spring period and the summer post-reproductive phase pMol amounts of beta-EP stimulate follicular androgen secretion in vitro, in a naloxone-reversible way. In either period, an inhibition of estradiol, possibly mediated via other factors, is the result of opioid action. In conclusion, these data demonstrate for the first time the widespread presence of beta-EP-related peptides in the frog Rana esculenta. Both immunocytochemical and biochemical evidence, as well as in vitro responses, support a physiological role for beta-EP in ovarian seasonality during the reproductive cycle of this amphibian.
在哺乳动物中，促阿片-黑素细胞皮质素原相关肽在下丘脑-垂体和卵巢水平均参与生殖过程。通过免疫细胞化学、生物化学和生理学的“体外”研究，我们在此提供证据表明在食用蛙（Rana esculenta）中存在一个弥散的POMC相关阿片系统。卵巢β-内啡肽（β-EP）在卵泡膜细胞中表达，并且在生殖周期中与卵泡发育呈负相关变化。卵巢的季节性变化与大脑或垂体中的不同。卵巢中乙酰化β-EP与天然β-EP的比例在生殖期也会发生变化，从而影响该肽的生物活性。在生殖春季和夏季生殖后期，皮摩尔量的β-EP均可在体外以纳洛酮可逆的方式刺激卵泡雄激素分泌。在这两个时期，阿片类药物作用的结果是可能通过其他因素介导的雌二醇抑制。总之，这些数据首次证明了食用蛙中广泛存在β-EP相关肽。免疫细胞化学和生物化学证据以及体外反应均支持β-EP在这种两栖动物生殖周期中的卵巢季节性变化中发挥生理作用。
