Proulx-Ferland L, Meunier H, Côté J, Dumont D, Gagné B, Labrie F
J Steroid Biochem. 1983 Jul;19(1B):439-45. doi: 10.1016/0022-4731(83)90201-7.
Alpha 1-adrenergic agents are potent stimulators of ACTH secretion directly at the pituitary level as observed using anterior pituitary cells in primary culture and by in vivo studies. On the other hand, beta-adrenergic as well as antidopaminergic agents are also potent stimulators of ACTH secretion but at a suprapituitary level, since no effect of these compounds are observed in vitro. CRF administration has been found to lead to rapid and parallel increases in ACTH and alpha-MSH concentrations in rat plasma and the mechanism of action of CRF has been studied in vitro using rat anterior and intermediate lobe of pituitary gland for ACTH and alpha-MSH secretion, respectively. In both cases, CRF stimulates adenylate cyclase activity at ED50 values of 70 and 350 nM for ACTH and alpha-MSH, respectively. CRF stimulates adenylate cyclase activity at least partly through a guanyl nucleotide-dependent mechanism. Using rat pars intermedia cells in culture, we have demonstrated the presence, in addition of a CRF receptor, of a beta 2-adrenergic receptor which stimulates cyclic AMP accumulation and alpha-MSH secretion and of a dopaminergic receptor which inhibits cellular activity. These results have been confirmed in in vivo studies where isoproterenol and thioproperazine (a dopamine antagonist) lead to a rapid increase of alpha-MSH secretion.
α1肾上腺素能药物是促肾上腺皮质激素（ACTH）分泌的强效刺激剂，在原代培养的垂体前叶细胞实验以及体内研究中均观察到其可直接作用于垂体水平。另一方面，β肾上腺素能药物以及抗多巴胺能药物也是ACTH分泌的强效刺激剂，但作用于垂体以上水平，因为在体外实验中未观察到这些化合物的作用。已发现给予促肾上腺皮质激素释放因子（CRF）可导致大鼠血浆中ACTH和α-促黑素（α-MSH）浓度迅速且平行升高，并且已分别使用大鼠垂体前叶和中间叶在体外研究了CRF的作用机制，以观察其对ACTH和α-MSH分泌的影响。在这两种情况下，CRF分别以70和350 nM的半数有效剂量（ED50）刺激腺苷酸环化酶活性，以促进ACTH和α-MSH分泌。CRF至少部分通过一种依赖鸟苷酸的机制刺激腺苷酸环化酶活性。利用培养的大鼠垂体中间叶细胞，我们证实除了CRF受体外，还存在一种β2肾上腺素能受体，其可刺激环磷酸腺苷（cAMP）积累和α-MSH分泌，以及一种多巴胺能受体，其可抑制细胞活性。这些结果在体内研究中得到了证实，其中异丙肾上腺素和硫丙嗪（一种多巴胺拮抗剂）可导致α-MSH分泌迅速增加。
