Bentley A M, Wallis M
J Endocrinol. 1986 Jun;109(3):313-20. doi: 10.1677/joe.0.1090313.
Experiments were carried out on the antagonistic effects of opiates on the inhibition by dopamine of prolactin secretion from rat anterior pituitary glands. Dose-response and time-course experiments were carried out using both static incubation of paired hemipituitary glands and perifusion of whole glands. Dopamine (10-1000 nmol/l) was found to have an inhibitory effect on prolactin secretion, but at a lower concentration (0.1 nmol/l) a small stimulation was observed. Against an inhibition established with 100 nmol dopamine/l in static incubation, the three opiates under study, morphine sulphate, Leu5-enkephalin and D-Ala2,Met5-enkephalin (DAME), had a maximum antagonistic effect at 50-1000 nmol/l in a 90-min incubation. Morphine and DAME were rather more effective than Leu5-enkephalin, possibly because of degradation of the latter. Naloxone reversed the effect of morphine. All three opiates showed little effect on dopamine-inhibited prolactin secretion in a perifusion system. The data accord with previous suggestions that prolactin secretion may be stimulated both by very low concentrations of dopamine and by opiates acting to reverse the inhibition exerted by higher dopamine concentrations. It should be noted that both morphine and the enkephalins have similar effects on prolactin secretion, despite their normal specificity for different opiate receptors; their actions on the pituitary may thus be rather non-specific.
进行了关于阿片类药物对多巴胺抑制大鼠垂体前叶催乳素分泌的拮抗作用的实验。使用成对半垂体的静态孵育和全垂体的灌流进行了剂量反应和时间进程实验。发现多巴胺（10 - 1000 nmol/l）对催乳素分泌有抑制作用，但在较低浓度（0.1 nmol/l）时观察到轻微的刺激作用。在静态孵育中，针对用100 nmol多巴胺/ l建立的抑制作用，所研究的三种阿片类药物，硫酸吗啡、亮氨酸脑啡肽和D - 丙氨酸2，甲硫氨酸5 - 脑啡肽（DAME），在90分钟孵育中，在50 - 1000 nmol/l时具有最大拮抗作用。吗啡和DAME比亮氨酸脑啡肽更有效，可能是因为后者会降解。纳洛酮可逆转吗啡的作用。在灌流系统中，所有三种阿片类药物对多巴胺抑制的催乳素分泌几乎没有影响。这些数据与先前的推测一致，即极低浓度的多巴胺和作用于逆转较高多巴胺浓度所施加抑制作用的阿片类药物均可刺激催乳素分泌。应当指出的是，尽管吗啡和脑啡肽对不同阿片受体具有正常的特异性，但它们对催乳素分泌具有相似的作用；因此它们对垂体的作用可能相当非特异性。
