D'Occhio M J, Setchell B P
J Endocrinol. 1984 Dec;103(3):371-6. doi: 10.1677/joe.0.1030371.
The capacity of the anterior pituitary gland and testes in mature bulls (705 +/- 9 (S.E.M.) kg body wt, n = 4) to respond to graded doses of LH-releasing hormone (LHRH) was assessed relative to endogenous profiles of LH and testosterone secretion. Endogenous hormone profiles were determined by bleeding bulls at 20-min intervals for 12 h. Responses to LHRH were assessed on successive days after single intravenous injections of 1, 5, 10, 50 or 100 ng LHRH/kg body wt. Blood samples were taken at -40, -20, 0, 10, 20, 30, 40, 60 and 120 min relative to LHRH injection. During a 12-h bleed bulls showed spontaneous pulses of LH and testosterone which had peak amplitudes of 2.6 +/- 0.5 micrograms/l and 44.5 +/- 7.1 nmol/l respectively. Respective peak LH (micrograms/l) and testosterone (nmol/l) responses to LHRH were as follows: 1 ng LHRH (3.0 +/- 0.7; 47.3 +/- 4.1); 5 ng LHRH (8.0 +/- 1.2; 52.8 +/- 6.2); 10 ng LHRH (11.1 +/- 2.3; 57.7 +/- 9.1); 50 ng LHRH (19.2 +/- 2.8; 47.9 +/- 8.6); 100 ng LHRH (19.1 +/- 4.7; 43.9 +/- 6.4). A dose of 1 ng LHRH/kg produced LH and testosterone responses which were comparable in amplitude to spontaneous peaks in the respective hormone. There was a linear (y = 0.28 X + 5.72; r = 0.81) increase in the LH response to doses of LHRH between 1 and 50 ng/kg; corresponding testosterone responses showed no relationship with the dose of LHRH. The capacity of the anterior pituitary gland to release amounts of LH eight to ten times in excess of those secreted during spontaneous peaks suggests that (1) there exists a large releasable store of LH in the anterior pituitary gland and (2) hypothalamic LHRH is a limiting factor in gonadotrophin secretion. In contrast to LH release, the androgenic response of the testes to acute gonadotrophic stimulation is determined largely by prevailing steroidogenic activity.
相对于促黄体生成素（LH）和睾酮分泌的内源性变化情况，评估了成熟公牛（体重705±9（标准误）千克，n = 4）垂体前叶和睾丸对不同剂量促黄体生成素释放激素（LHRH）的反应能力。通过每隔20分钟采集公牛血液样本，持续12小时来测定内源性激素变化情况。在单次静脉注射1、5、10、50或100 ng LHRH/千克体重后的连续几天评估对LHRH的反应。相对于LHRH注射，在-40、-20、0、10、20、30、40、60和120分钟采集血样。在12小时的采血过程中，公牛表现出LH和睾酮的自发脉冲，其峰值幅度分别为2.6±0.5微克/升和44.5±7.1纳摩尔/升。对LHRH的LH（微克/升）和睾酮（纳摩尔/升）峰值反应分别如下：1 ng LHRH（3.0±0.7；47.3±4.1）；5 ng LHRH（8.0±1.2；52.8±6.2）；10 ng LHRH（11.1±2.3；57.7±9.1）；50 ng LHRH（19.2±2.8；47.9±8.6）；100 ng LHRH（19.1±4.7；43.9±6.4）。1 ng LHRH/千克的剂量产生的LH和睾酮反应在幅度上与各自激素的自发峰值相当。在1至50 ng/千克的LHRH剂量之间，LH反应呈线性增加（y = 0.28X + 5.72；r = 0.81）；相应的睾酮反应与LHRH剂量无关。垂体前叶释放的LH量比自发峰值期间分泌量高出八至十倍，这表明：（1）垂体前叶存在大量可释放的LH储备；（2）下丘脑LHRH是促性腺激素分泌的限制因素。与LH释放不同，睾丸对急性促性腺激素刺激的雄激素反应在很大程度上取决于当时的类固醇生成活性。
