Bugajski J, Gadek A
Agents Actions. 1984 Apr;14(3-4):550-3. doi: 10.1007/BF01973869.
In conscious rats clonidine given intracerebroventricularly 1 h prior to a mild stress of immobilization intensified the stress-induced increase of pituitary-adrenocortical response, measured indirectly through corticosterone concentration in blood serum. The corticosterone response to clonidine was abolished by i.c.v. pretreatment of rats with yohimbine, an alpha 2-adrenergic antagonist, and was antagonized by pretreatment with phenoxybenzamine, an alpha 1-adrenergic antagonist. Clonidine intensified also the corticosterone response induced in stressed rats by i.c.v. injected histamine, 2-pyridylethylamine (PEA), a H1-receptor agonist, and dimaprit, a H2-receptor agonist. The depletion of brain catecholamines by alpha-methyl-p-tyrosine (alpha-MT) considerably increased the corticosterone response to stress but did not substantially change the response to histamine, PEA and dimaprit in stressed rats. These results suggest that clonidine increases the corticosterone secretion induced by a mild stress and histamine and histamine H1 and H2 agonists mainly through the activation of central alpha 2-adrenoceptors. The increase by alpha-MT of the stress-induced corticosterone response may indicate the inhibitory role of central catecholamines in the pituitary-adrenocortical response to stress in rats.
在清醒大鼠中，于轻度固定应激前1小时脑室内注射可乐定，可增强应激诱导的垂体-肾上腺皮质反应，该反应通过血清皮质酮浓度间接测定。用α2-肾上腺素能拮抗剂育亨宾对大鼠进行脑室内预处理可消除可乐定引起的皮质酮反应，而用α1-肾上腺素能拮抗剂酚苄明预处理则可拮抗该反应。可乐定还可增强应激大鼠经脑室内注射组胺、H1受体激动剂2-吡啶乙胺（PEA）和H2受体激动剂二甲双胍所诱导的皮质酮反应。用α-甲基对酪氨酸（α-MT）耗竭脑内儿茶酚胺可显著增强应激大鼠对应激的皮质酮反应，但对组胺、PEA和二甲双胍的反应无实质性改变。这些结果表明，可乐定主要通过激活中枢α2-肾上腺素能受体来增加轻度应激、组胺以及组胺H1和H2激动剂所诱导的皮质酮分泌。α-MT增强应激诱导皮质酮反应可能表明中枢儿茶酚胺对大鼠垂体-肾上腺皮质对应激反应具有抑制作用。
