Haidamous M, Kouyoumdjian J C, Briley P A, Gonnard P
Eur J Pharmacol. 1980 May 16;63(4):287-94. doi: 10.1016/0014-2999(80)90257-5.
Cerebellar cyclic GMP levels can be altered by neurotransmitters and their receptor agonists and antagonists. In this study, we investigated the action of noradrenaline and certain drugs affecting alpha- and beta-adrenoceptors on rat cerebellaceptor agonists such as methoxamine and phenylephrine increased cGMP levels. alpha-Adrenoceptor antagonists such as phentolamine, phenoxybenzamine and ARC 239 decreased cGMP levels, whereas yohimbine and piperoxane which are known to act as presynaptic alpha-adrenoceptor antagonists had no effect. The action of clonidine which decreased cGMP levels at low doses was probably due to the fact that this adrenoceptor agonist inhibited the release of noradrenaline from adrenergic nerve terminals, since piperoxane injected prior to clonidine antagonized the effect of clonidine on cerebellar cGMP, and since pretreatment of the animals with 6-hydroxydopamine partially antagonized the effect of clonidine. Isoproterenol, a beta-noradrenergic agonist had no effect on cerebellar cGMP levels. Propranolol, a beta-noradrenergic antagonist decreased cGMP levels. Phenoxybenzamine or propranolol injected prior to noradrenaline decreased cerebellar cGMP.
小脑环磷酸鸟苷（cGMP）水平可被神经递质及其受体激动剂和拮抗剂改变。在本研究中，我们研究了去甲肾上腺素以及某些影响α-和β-肾上腺素能受体的药物对大鼠小脑的作用。α-肾上腺素能受体激动剂如甲氧明和去氧肾上腺素可提高cGMP水平。α-肾上腺素能受体拮抗剂如酚妥拉明、酚苄明和ARC 239可降低cGMP水平，而已知作为突触前α-肾上腺素能受体拮抗剂的育亨宾和哌罗克生则无作用。低剂量时降低cGMP水平的可乐定的作用可能是由于这种肾上腺素能受体激动剂抑制了去甲肾上腺素能神经末梢释放去甲肾上腺素，因为在可乐定之前注射哌罗克生可拮抗可乐定对小脑cGMP的作用，并且因为用6-羟基多巴胺对动物进行预处理可部分拮抗可乐定的作用。β-去甲肾上腺素能激动剂异丙肾上腺素对小脑cGMP水平无作用。β-去甲肾上腺素能拮抗剂普萘洛尔可降低cGMP水平。在去甲肾上腺素之前注射酚苄明或普萘洛尔可降低小脑cGMP。
