Pedersen L J, Jensen K H, Jørgensen E
National Institute of Animal Science, Dept. of Research in Pigs and Horses, Tjele, Denmark.
Acta Vet Scand. 1996;37(2):153-61. doi: 10.1186/BF03548108.
The effect of intermittent electroshock on LH and estradiol secretory pattern and on reaching puberty was studied in 24 prepubertal gilts. Twelve gilts 115-168 days of age received unpredictable and inescapable electroshocks 0-5 times daily between 8 am and 4 pm and 12 gilts served as controls. At an age of 168 +/- 0.7 days all gilts were moved, regrouped and exposed to a boar for 30 min. Observations for signs of oestrus were carried out twice daily. Indwelling jugular catheters were inserted into 8 gilts on each treatment after the initial boar contact. Blood samples were collected to determine LH profiles for 4 h every 15 min on day 2 and day 4 after the initial boar contact. The remaining 4 gilts on each treatment were catheterized one day prior to the initial boar contact and blood was collected to determine LH profiles the day before initial boar contact and day 1 and day 2 after initial boar contact for 6 h every 15 min. In addition, blood samples were collected and analyzed for LH and estradiol from all gilts daily at 8 am, 12 am and 4 pm for the first 3 days following the initial boar contact and thereafter every 4 h until the end of oestrus (diurnal samples). Samples taken daily at noon the first 5 days following initial boar contact were analyzed for cortisol. The electroshock treatment significantly increased the age at puberty (p = 0.04) and tended to decrease the mean LH concentration prior to the preovulatory LH surge (p = 0.08) and the maximal concentration of LH during the preovulatory LH surge (p = 0.07). The apparent down regulation of the plasma concentration of LH was not associated with increased activity in the hypothalamus-pituitary-adrenal axis in that the basal concentration of cortisol was not affected by treatment. This indicates that other physiological mechanisms are involved in stress-induced suppression of LH.
在24头青春期前的小母猪中研究了间歇性电击对促黄体生成素（LH）和雌二醇分泌模式以及进入青春期的影响。12头115 - 168日龄的小母猪在上午8点至下午4点期间每天接受0 - 5次不可预测且无法逃避的电击，另外12头小母猪作为对照。在168±0.7日龄时，所有小母猪被转移、重新分组并与一头公猪接触30分钟。每天观察两次发情迹象。在初次与公猪接触后，对每种处理的8头小母猪插入颈静脉留置导管。在初次与公猪接触后的第2天和第4天，每隔15分钟采集一次血样，持续4小时，以测定LH水平。每种处理的其余4头小母猪在初次与公猪接触前一天插入导管，并在初次与公猪接触前一天、初次与公猪接触后第1天和第2天每隔15分钟采集一次血样，持续6小时，以测定LH水平。此外，在初次与公猪接触后的前3天，每天上午8点、中午12点和下午4点从所有小母猪采集血样并分析LH和雌二醇，此后每4小时采集一次，直至发情结束（昼夜样本）。在初次与公猪接触后的前5天，每天中午采集的样本用于分析皮质醇。电击处理显著提高了青春期的年龄（p = 0.04），并且倾向于降低排卵前LH峰之前的平均LH浓度（p = 0.08）以及排卵前LH峰期间LH的最大浓度（p = 0.07）。LH血浆浓度的明显下调与下丘脑 - 垂体 - 肾上腺轴活性增加无关，因为皮质醇的基础浓度不受处理影响。这表明其他生理机制参与了应激诱导的LH抑制。
