Kiem D T, Bartha L, Makara G B
Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest.
Brain Res. 1991 Nov 1;563(1-2):107-13. doi: 10.1016/0006-8993(91)91521-2.
We studied the effect of dexamethasone (DEX) implantation in male Wistar rats to elucidate the site of action of morphine-induced prolactin (PRL), growth hormone (GH), adrenocorticotropic hormone (ACTH) and corticosterone (B) secretion. DEX or cholesterol was implanted in the close vicinity of the paraventricular (PVN), or the arcuate nuclei (ARN) of the hypothalamus or into the hippocampus. Five days after implantation blood samples were taken 30 min after i.p. morphine by decapitation or through an indwelling cannula 15, 30, 60 min after i.v. injection. DEX implanted near the PVN resulted in a blockade of morphine-induced ACTH and B secretion. In contrast, GH response to morphine was enhanced, while that of PRL was unchanged. DEX implanted near the ARN significantly inhibited the PRL-releasing effect of morphine, but was without any influence on the PRL secretion induced by haloperidol. There was a partial reduction in the B response to morphine, and GH secretion was unchanged. Dorsal hippocampal implants were without any effect on the morphine-induced GH, PRL or B secretion. We suggest that the site of glucocorticoid inhibitory action in the hypothalamus is the PVN for the opiate-induced ACTH/B secretion, and the ARN for the morphine-induced PRL release. The enhanced GH response to morphine observed in DEX-PVN implanted rats might be due to a decreased somatostatin tone.
我们研究了地塞米松（DEX）植入雄性Wistar大鼠体内的效果，以阐明吗啡诱导的催乳素（PRL）、生长激素（GH）、促肾上腺皮质激素（ACTH）和皮质酮（B）分泌的作用位点。将DEX或胆固醇植入下丘脑室旁核（PVN）或弓状核（ARN）附近或海马体中。植入后5天，通过腹腔注射吗啡30分钟后断头采血，或静脉注射后15、30、60分钟通过留置套管采血。植入PVN附近的DEX导致吗啡诱导的ACTH和B分泌受阻。相比之下，GH对吗啡的反应增强，而PRL的反应不变。植入ARN附近的DEX显著抑制了吗啡的PRL释放作用，但对氟哌啶醇诱导的PRL分泌没有任何影响。B对吗啡的反应部分降低，GH分泌不变。海马体背侧植入物对吗啡诱导的GH、PRL或B分泌没有任何影响。我们认为，下丘脑糖皮质激素抑制作用的位点对于阿片类药物诱导的ACTH/B分泌是PVN，对于吗啡诱导的PRL释放是ARN。在植入DEX-PVN的大鼠中观察到的GH对吗啡反应增强可能是由于生长抑素张力降低。
