Spiegel K, Kourides I A, Pasternak G W
Life Sci. 1982;31(20-21):2177-80. doi: 10.1016/0024-3205(82)90112-6.
Morphine has a variety of actions on the release of pituitary hormones in addition to its analgesic actions. In the rat, morphine releases prolactin and growth hormone at doses comparable to those active in the tailflick analgesic assay. Naloxazone selectively inhibits the high affinity (mu 1) binding site and dramatically decreases morphine's analgesic potency for over 24 hours. In an effort to determine the opiate receptor mechanisms of morphine-induced prolactin and growth hormone release, groups of rats were treated with either naloxone or naloxazone and 24 hours later the prolactin and growth hormone response to morphine sulfate determined. Peak prolactin levels in the group treated the previous day with naloxone were very similar to levels in untreated controls. However, the peak prolactin levels in the group that received naloxazone the day before were depressed 80% (p less than 0.005). By contrast, growth hormone levels in the naloxazone-treated animals were actually higher than in the naloxone-treated group. Thus prolactin release, like analgesia, appears to be mediated through high affinity, or mu 1, sites, while growth hormone release is not.
吗啡除具有镇痛作用外，对垂体激素的释放还有多种作用。在大鼠中，吗啡释放催乳素和生长激素的剂量与甩尾镇痛试验中的有效剂量相当。纳洛沙宗选择性抑制高亲和力（μ1）结合位点，并在超过24小时内显著降低吗啡的镇痛效力。为了确定吗啡诱导催乳素和生长激素释放的阿片受体机制，将几组大鼠用纳洛酮或纳洛沙宗处理，24小时后测定催乳素和生长激素对硫酸吗啡的反应。前一天用纳洛酮处理的组中催乳素峰值水平与未处理对照组的水平非常相似。然而，前一天接受纳洛沙宗处理的组中催乳素峰值水平降低了80%（p小于0.005）。相比之下，纳洛沙宗处理动物的生长激素水平实际上高于纳洛酮处理组。因此，催乳素的释放与镇痛一样，似乎是通过高亲和力或μ1位点介导的，而生长激素的释放则不是。
