Palta P, Mondal S, Prakash B S, Madan M L
Embryo Biotechnology Centre, National Dairy Research Institute, Karnal (Haryana), India.
Theriogenology. 1997 Apr 1;47(5):989-95. doi: 10.1016/s0093-691x(97)00055-1.
The present study investigated the peripheral plasma inhibin levels in relation to 1) the stage of estrous cycle and the effect of climatic variations. Blood samples were collected from cyclic buffalo (n=5) once daily for 32 consecutive days during the tropical hot humid (summer) and cold (winter) seasons. Estrus was recorded by parading a vasectomized bull as well as by plasma progesterone determination. In the winter season, peripheral inhibin concentrations which were lowest (0.35 +/- 0.02 ng/ml) during the mid-luteal phase of estrous cycle (Day 6 to Day 14, Day 0 = day of estrus) increased significantly (P < 0.02) to 0.47 +/- 0.04 ng/ml during the late luteal phase (Day -4 to Day -2) and then further to 0.52 +/- 0.03 ng/ml (P< 0.02) during the periestrus phase (Day -1 to Day 1). Inhibin concentrations then decreased significantly (P < 0.02) to 0.40 +/- 0.03 ng/ml during the early luteal phase (Day 2 to Day 5). In the summer season the differences in peripheral inhibin concentrations among different phases of estrous cycle were found to be nonsignificant. A comparison of the circulating inhibin concentrations between the two seasons indicated that inhibin concentrations were significantly higher in the late luteal phase (P < 0.01) and periestrus phase (P < 0.05) during the winter season compared with corresponding periods during the summer season. The present study suggests that peripheral inhibin concentrations change in the estrous cycle during cooler breeding season and that environmental heat stress can cause a reduction in peripheral inhibin concentrations.
1）发情周期阶段及气候变化的影响。在热带炎热潮湿（夏季）和寒冷（冬季）季节，连续32天每天从5头处于发情周期的水牛采集血样。通过牵行输精管结扎公牛以及测定血浆孕酮来记录发情情况。在冬季，发情周期黄体中期（第6天至第14天，第0天 = 发情日）外周抑制素浓度最低（0.35±0.02 ng/ml），在黄体后期（第 -4天至第 -2天）显著升高（P < 0.02）至0.47±0.04 ng/ml，然后在发情前期（第 -1天至第1天）进一步升至0.52±0.03 ng/ml（P < 0.02）。随后在黄体早期（第2天至第5天）抑制素浓度显著下降（P < 0.02）至0.40±0.03 ng/ml。在夏季，发情周期不同阶段外周抑制素浓度差异不显著。两季循环抑制素浓度比较表明，与夏季相应时期相比，冬季黄体后期（P < 0.01）和发情前期（P < 0.05）的抑制素浓度显著更高。本研究表明，在较凉爽的繁殖季节，外周抑制素浓度在发情周期中会发生变化，并且环境热应激会导致外周抑制素浓度降低。
