Ruotsalainen S, Haapalinna A, Riekkinen P J, Sirviö J
A.I. Virtanen Institute, University of Kuoplo, Finland.
Pharmacol Biochem Behav. 1997 Jan;56(1):31-40. doi: 10.1016/S0091-3057(96)00151-7.
The present study investigated the role of alpha 2-adrenergic mechanisms in the performance of motor responses, attention and short-term memory in rats. A low dose (3.0 micrograms/kg, s.c.) of dexmedetomidine, an alpha 2-adrenoceptor agonist, reduced response tendency in an attentional task and a working memory task, but it did not affect the choice accuracy of rats. Atipamezole (300 micrograms/kg), an alpha 2-adrenoceptor antagonist, increased anticipatory responding. Although atipamezole did not affect the number of omissions, it reversed the effects of dexmedetomidine on that parameter. We also investigated the effects of dexmedetomidine in rats with partial destruction of noradrenergic nerves induced by the neurotoxin DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride). On its own, DSP-4 treatment did not affect choice accuracy or behavioural activity of rats in the attentional task. The effects of dexmedetomidine (0.3-3.0 micrograms/kg) on anticipatory responses did not differ between controls and DSP-4 group. Furthermore, the effect on omissions was not consistently diminished in DSP-4 treated rats. These results suggest that the activation of postsynaptic alpha 2-adrenoreceptors may be responsible for dexmedetomidine-induced reduction of response tendency while attention and short-term memory are not markedly affected.
本研究调查了α2-肾上腺素能机制在大鼠运动反应、注意力和短期记忆表现中的作用。低剂量（3.0微克/千克，皮下注射）的右美托咪定，一种α2-肾上腺素能受体激动剂，降低了注意力任务和工作记忆任务中的反应倾向，但不影响大鼠的选择准确性。α2-肾上腺素能受体拮抗剂阿替美唑（300微克/千克）增加了预期反应。虽然阿替美唑不影响遗漏次数，但它逆转了右美托咪定对该参数的影响。我们还研究了右美托咪定对由神经毒素DSP-4（N-（2-氯乙基）-N-乙基-2-溴苄胺盐酸盐）诱导的去甲肾上腺素能神经部分破坏的大鼠的影响。单独使用DSP-4治疗不影响大鼠在注意力任务中的选择准确性或行为活动。右美托咪定（0.3 - 3.0微克/千克）对预期反应的影响在对照组和DSP-4组之间没有差异。此外，在DSP-4处理的大鼠中，对遗漏的影响并没有持续减弱。这些结果表明，突触后α2-肾上腺素能受体的激活可能是右美托咪定诱导反应倾向降低的原因，而注意力和短期记忆并未受到明显影响。
