Livesey J H, Donald R A, Irvine C H, Redekopp C, Alexander S L
Department of Endocrinology, Princess Margaret Hospital, Christchurch, New Zealand.
Endocrinology. 1988 Aug;123(2):713-20. doi: 10.1210/endo-123-2-713.
Plasma ACTH, arginine vasopressin (AVP), and alpha MSH were measured in pituitary venous effluent at 5-min intervals from five unanesthetized horses during cortisol infusion and after an iv bolus of AVP or ovine (o) CRF. In control experiments (no hormone) there was a significant overall correlation between the timing of concentration changes in ACTH and alpha MSH. Cortisol infusion increased jugular cortisol levels by 70% and was associated with a reduction in mean ACTH, AVP, and alpha MSH secretion rates and ACTH peak secretion rate, but did not alter the observed pulse frequencies of these hormones. Administration of AVP raised plasma concentrations to a level comparable to the spontaneous peaks in pituitary venous blood and resulted in an increase in the secretion of ACTH and alpha MSH in all horses. Furthermore, spontaneous AVP peaks occurred in pituitary venous blood between 90 and 180 min after AVP injection, indicating that the exogenous hormone did not suppress AVP secretion. oCRF administration led to a prolonged elevation in plasma CRF and an increase in secretion of ACTH and alpha MSH, but not AVP, in all horses. The pulsatile secretion of ACTH and alpha MSH was maintained despite plasma CRF levels in excess of 400 pmol/liter, and the timing of concentration changes in AVP and ACTH continued to be highly correlated. It is concluded that pulsatile ACTH secretion continues during cortisol, oCRF, or AVP administration. Like that of ACTH, alpha MSH secretion is stimulated by oCRF and AVP administration and suppressed by cortisol. Although the timing of concentration changes in ACTH and alpha MSH is highly correlated, the correlation of the actual concentrations of these two hormones varies considerably in different animals.
在五匹未麻醉的马中，于皮质醇输注期间以及静脉推注精氨酸加压素（AVP）或羊促肾上腺皮质激素释放因子（oCRF）后，每隔5分钟测量垂体静脉流出液中的血浆促肾上腺皮质激素（ACTH）、精氨酸加压素（AVP）和α-促黑素（α-MSH）。在对照实验（无激素）中，ACTH和α-MSH浓度变化的时间之间存在显著的总体相关性。皮质醇输注使颈静脉皮质醇水平升高70%，并伴有平均ACTH、AVP和α-MSH分泌率以及ACTH峰值分泌率降低，但未改变这些激素的脉冲频率。给予AVP使血浆浓度升高至与垂体静脉血中的自发峰值相当的水平，并导致所有马匹的ACTH和α-MSH分泌增加。此外，在注射AVP后90至180分钟之间，垂体静脉血中出现自发的AVP峰值，表明外源性激素并未抑制AVP分泌。给予oCRF导致所有马匹的血浆CRF持续升高，ACTH和α-MSH分泌增加，但AVP分泌未增加。尽管血浆CRF水平超过400 pmol/升，但ACTH和α-MSH的脉冲分泌仍得以维持，并且AVP和ACTH浓度变化的时间仍然高度相关。得出的结论是，在给予皮质醇、oCRF或AVP期间，ACTH的脉冲分泌持续存在。与ACTH一样，α-MSH的分泌受到oCRF和AVP的刺激，并受到皮质醇的抑制。尽管ACTH和α-MSH浓度变化的时间高度相关，但这两种激素的实际浓度在不同动物中的相关性差异很大。
