Browning R, Schrick F N, Thompson F N, Wakefield T
Cooperative Agricultural Research Program and the School of Agriculture and Home Economics, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, TN 37209, USA.
Anim Reprod Sci. 2001 May 31;66(3-4):135-49. doi: 10.1016/s0378-4320(01)00098-7.
The objective of this research was to determine if ergotamine, an ergopeptine alkaloid isolated from Neotyphodium-infected grasses and associated with toxicoses in livestock, altered plasma concentrations of reproductive hormones in follicular phase heifers and in cows given a progestin implant. In Experiment 1, blood was sampled for 8h from four cycling heifers 2 days after synchronized luteolysis. Heifers were treated with ergotamine tartrate (19microg/kg) i.v. or saline vehicle in a simple cross-over design after 1h of pre-treatment blood sampling. Heifers received oxytocin (100USP units) i.v. 4h after ergotamine or saline treatment. Ergotamine reduced (P<0.01) prolactin concentrations from 1 to 4h post-treatment and increased (P<0.01) 13,14-dihydro-15-keto prostaglandin F2alpha (PGFM) concentrations from 2 to 5h post-treatment. A PGFM response to oxytocin was not detected. In Experiment 2, blood was sampled for 8h from six cycling cows 10 days after receiving a s.c. norgestomet implant. Cows were treated i.v. with ergotamine (20microg/kg) or saline in a simple cross-over design after 1h of pre-treatment blood sampling. Cows received gonadorelin (GnRH, 100microg) i.v. 1h after ergotamine or saline. Cows received oxytocin (100USP units) i.v. 4h after ergotamine or saline treatment. Ergotamine reduced (P<0.01) serum prolactin concentrations by 120min after treatment, with prolactin returning to pre-treatment concentrations by 200min after treatment. Saline-treated cows had lower (P<0.01) prolactin by 280min after treatment. Ergotamine-treated cows had higher (P<0.01) PGFM concentrations compared to saline-treated cows 120-240min after treatments, but the groups exhibited similar increases in PGFM after oxytocin. Plasma LH and FSH concentrations increased to peaks 100-120min after GnRH for both groups. However, the LH response to GnRH was greater (P<0.01) for ergotamine-treated cows. In summary, ergotamine lowered prolactin and elevated PGFM concentrations in follicular phase heifers and cows on norgestomet therapy. Ergotamine increased the LH response to exogenous GnRH in cows with norgestomet implants. These data highlight the potential of ergopeptine alkaloids to affect reproduction through altered endocrine function.
本研究的目的是确定麦角胺（一种从感染内生真菌的禾本科植物中分离出来的麦角肽生物碱，与家畜中毒有关）是否会改变处于卵泡期的小母牛以及植入孕激素的母牛的生殖激素血浆浓度。在实验1中，在同步黄体溶解2天后，从4头处于发情周期的小母牛身上采集8小时的血液样本。在预处理血液采样1小时后，小母牛按照简单交叉设计接受静脉注射酒石酸麦角胺（19μg/kg）或生理盐水。在麦角胺或生理盐水处理4小时后，小母牛静脉注射催产素（100USP单位）。麦角胺使处理后1至4小时的催乳素浓度降低（P<0.01），并使处理后2至5小时的13,14-二氢-15-酮前列腺素F2α（PGFM）浓度升高（P<0.01）。未检测到PGFM对催产素的反应。在实验2中，在6头处于发情周期的母牛皮下植入炔诺孕酮10天后，采集8小时的血液样本。在预处理血液采样1小时后，母牛按照简单交叉设计静脉注射麦角胺（20μg/kg）或生理盐水。在麦角胺或生理盐水处理1小时后，母牛静脉注射促性腺激素释放激素（GnRH，100μg）。在麦角胺或生理盐水处理4小时后，母牛静脉注射催产素（100USP单位）。麦角胺使处理后120分钟时血清催乳素浓度降低（P<0.01），处理后200分钟时催乳素恢复到处理前浓度。生理盐水处理的母牛在处理后280分钟时催乳素浓度较低（P<0.01）。与生理盐水处理的母牛相比，麦角胺处理的母牛在处理后120 - 240分钟时PGFM浓度较高（P<0.01），但两组在注射催产素后PGFM的升高幅度相似。两组在注射GnRH后100 - 120分钟时血浆促黄体生成素（LH）和促卵泡生成素（FSH）浓度均升至峰值。然而，麦角胺处理的母牛对GnRH的LH反应更大（P<0.01）。总之，麦角胺降低了处于卵泡期的小母牛以及接受炔诺孕酮治疗的母牛的催乳素浓度，并升高了PGFM浓度。麦角胺增强了植入炔诺孕酮的母牛对外源性GnRH的LH反应。这些数据突出了麦角肽生物碱通过改变内分泌功能影响生殖的潜力。
