Warenycia M W, McKenzie G M
Department of Pharmacology, University of Alberta, Edmonton, Canada.
Pharmacol Biochem Behav. 1989 Jun;33(2):489-91. doi: 10.1016/0091-3057(89)90536-4.
Striatal neurons of mature rats responded to 2.5 mg/kg dexamphetamine with increased multiple unit activity that followed the time course of drug-increased behavior. In contrast, in older (middle-aged) rats striatal neurons failed to respond to dexamphetamine with excitation. Behavioral responses were reduced by half as compared to mature rats. Retesting of these middle-aged rats with dexamphetamine did not result in either improved behavioral or neuronal responses and decreases in spontaneous MUA suggested dexamphetamine neurotoxicity in older animals. Since striatal neuronal responses and behavioral responses to dexamphetamine are greatly reduced, age-related impairment of dopaminergic neurotransmission may lead to in reductions in striatal neuronal excitation as well as feedback from dexamphetamine-induced behavior.
成熟大鼠的纹状体神经元对2.5毫克/千克的右旋苯丙胺有反应，其多个单位活动增加，且与药物增加行为的时间进程一致。相比之下，在老年（中年）大鼠中，纹状体神经元对右旋苯丙胺没有兴奋反应。与成熟大鼠相比，行为反应减少了一半。用右旋苯丙胺对这些中年大鼠进行重新测试，既没有改善行为反应也没有改善神经元反应，并且自发多单位活动（MUA）的减少表明老年动物存在右旋苯丙胺神经毒性。由于纹状体神经元对右旋苯丙胺的反应和行为反应大大降低，与年龄相关的多巴胺能神经传递损伤可能导致纹状体神经元兴奋的减少以及右旋苯丙胺诱导行为的反馈减少。
