Browning R, Thompson F N, Sartin J L, Leite-Browning M L
Cooperative Agricultural Research Program, Tennessee State University, Nashville 37209, USA.
J Anim Sci. 1997 Mar;75(3):796-802. doi: 10.2527/1997.753796x.
This research investigated whether ergot alkaloids associated with endophyte-infected tall fescue could alter plasma concentrations of pituitary hormones that regulate biological processes related to cattle performance. Seven Angus yearling steers received single i.v. injections of ergotamine tartrate, ergonovine maleate, or saline vehicle in a simple cross-over design. Each steer was given a different compound each week. Blood samples were collected at 15-min intervals for 45 min before and 240 min after treatments to assess plasma concentrations of prolactin, growth hormone, and LH. Respiratory rates were measured hourly to ascertain a systemic effect. Ambient temperature averaged 34 degrees C during data collection. Treatment x time was a significant source of variation for respiration rate and plasma concentrations of each hormone evaluated. Respiration rates were higher for ergonovine than for saline (P < .02) and ergotamine (P < .07) 30 min after treatment, but they were higher (P < .05) for ergotamine than for ergonovine and saline by 210 min after treatment. Both alkaloids transiently elevated (P < .01) plasma growth hormone concentrations compared with before alkaloid treatment and after saline treatment. Ergotamine reduced (P < .01) plasma concentrations of prolactin and LH throughout the 120-min period after treatment compared with concentrations before ergotamine treatment and after saline treatment. Ergonovine lowered (P < .01) prolactin concentrations for a shorter time than ergotamine and did not affect mean LH concentrations. Results indicated that ergot alkaloids implicated as contributing agents to fescue toxicosis can alter plasma concentrations of pituitary hormones important to cattle production.
本研究调查了与内生真菌感染的高羊茅相关的麦角生物碱是否会改变调节与牛生产性能相关生物学过程的垂体激素的血浆浓度。七头安格斯一岁公牛以简单交叉设计接受了单次静脉注射酒石酸麦角胺、马来酸麦角新碱或生理盐水载体。每头公牛每周给予一种不同的化合物。在处理前45分钟和处理后240分钟，每隔15分钟采集血样，以评估催乳素、生长激素和促黄体生成素的血浆浓度。每小时测量呼吸频率以确定全身效应。数据收集期间环境温度平均为34摄氏度。处理×时间是呼吸频率和所评估的每种激素血浆浓度变化的一个重要来源。处理后30分钟，麦角新碱处理组的呼吸频率高于生理盐水组（P < 0.02）和酒石酸麦角胺组（P < 0.07），但处理后210分钟，酒石酸麦角胺组的呼吸频率高于麦角新碱组和生理盐水组（P < 0.05）。与生物碱处理前和生理盐水处理后相比，两种生物碱均使血浆生长激素浓度短暂升高（P < 0.01）。与酒石酸麦角胺处理前和生理盐水处理后相比，酒石酸麦角胺在处理后的120分钟内降低了（P < 0.01）催乳素和促黄体生成素的血浆浓度。麦角新碱降低催乳素浓度的时间比酒石酸麦角胺短（P < 0.01），且不影响促黄体生成素的平均浓度。结果表明，被认为是牛茅草中毒致病因素的麦角生物碱可改变对牛生产很重要的垂体激素的血浆浓度。
