Osawa T, Nakao T, Moriyoshi M, Nakada K
Department of Veterinary Obstetrics and Gynecology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
Anim Reprod Sci. 1998 Jun 30;52(1):27-38. doi: 10.1016/s0378-4320(98)00086-4.
The objectives were to evaluate the concentrations of beta-endorphin in peripheral circulation around parturition and to investigate their relationship to the concentrations of cortisol and postpartum resumption of pituitary and ovarian functions in dairy cows. Subjects were 21 Holstein-Friesian cows in late pregnancy. Blood samples were collected from these animals from day 270 in pregnancy until the first ovulation after calving. Average immunoreactive (IR) beta-endorphin concentrations in cows with dystocia (n = 8) in periparturient period (from day 270 of pregnancy until 24 h after calving) were slightly higher than those in cows with normal calving (n = 13) in the same period although the difference was not significant. During the periparturient period, the peak level of IR beta-endorphin was seen at the time of rupture in cows with normal calving and it was observed at the time of parturition in cows with dystocia. The trend of IR beta-endorphin secretion appeared to be concomitant with cortisol secretion in the periparturient period but not in postpartum period (from 24 h after calving until the first ovulation). Average IR beta-endorphin concentrations in cows with dystocia in the postpartum period were not significantly different from those in cows with normal calving. There was no significant association between average IR beta-endorphin concentrations in early postpartum period (from 24 h until 7 days after calving) and the responsiveness of luteinising hormone (LH) to exogenous GnRH administered on day 7 postpartum. However, a negative correlation (r = -0.593; n = 21; P = 0.004) was observed between average IR beta-endorphin concentrations and LH concentrations during the period from day 1 until the first ovulation in the 21 cows. In addition, a positive correlation (r = 0.498; n = 21; P = 0.020) was seen between the beta-endorphin concentrations and time to the first ovulation after calving. The results from this study suggest that beta-endorphin may release into peripheral blood differently from cortisol and that it may be involved in regulating LH secretion and thus the resumption of ovarian cyclicity in postpartum dairy cows.
本研究旨在评估奶牛分娩前后外周循环中β-内啡肽的浓度，并探讨其与皮质醇浓度以及产后垂体和卵巢功能恢复之间的关系。研究对象为21头妊娠后期的荷斯坦-弗里生奶牛。从妊娠第270天开始直至产后首次排卵，采集这些奶牛的血样。难产奶牛（n = 8）围产期（从妊娠第270天至产后24小时）的平均免疫反应性（IR）β-内啡肽浓度略高于同期顺产奶牛（n = 13），不过差异不显著。围产期，顺产奶牛在胎膜破裂时出现IRβ-内啡肽峰值水平，而难产奶牛在分娩时出现该峰值。围产期IRβ-内啡肽的分泌趋势似乎与皮质醇分泌相伴，但产后阶段（从产后24小时至首次排卵）并非如此。产后阶段，难产奶牛的平均IRβ-内啡肽浓度与顺产奶牛相比无显著差异。产后早期（从产后24小时至产后7天）的平均IRβ-内啡肽浓度与产后第7天注射外源性促性腺激素释放激素（GnRH）时促黄体生成素（LH）的反应性之间无显著关联。然而，在21头奶牛中，从第1天至首次排卵期间，平均IRβ-内啡肽浓度与LH浓度之间存在负相关（r = -0.593；n = 21；P = 0.004）。此外，β-内啡肽浓度与产后至首次排卵的时间之间存在正相关（r = 0.498；n = 21；P = 0.020）。本研究结果表明，β-内啡肽可能以与皮质醇不同的方式释放到外周血中，并且可能参与调节LH分泌，从而影响产后奶牛卵巢周期性的恢复。
