Norman A B, Blaker S N, Thal L, Creese I
Neurosci Lett. 1986 Oct 8;70(2):289-94. doi: 10.1016/0304-3940(86)90479-9.
Despite a 34% decrease in the activity of choline acetyltransferase (ChAT) in the rat cerebral cortex following lesions of the nucleus basalis, there were no changes in the Bmax of the antagonist ligands [3H]quinuclidinyl benzilate ((-)-[3H]QNB) or (-)-[3H]N-methylscopolamine ((-)-[3H]NMS). Furthermore, this treatment produced no significant change in the proportions or affinities of muscarinic receptors having high and low affinity for pirenzepine or (-)-NMS. These data indicate that putative M2 muscarinic receptors are not restricted to ChAT-containing neurons in rat cerebral cortex. In senescent compared to mature rats there was no significant loss of ChAT activity although a significant reduction in the Bmax of both (-)-[3H]QNB and (-)-[3H]NMS binding was observed. However, no changes in the competition of pirenzepine or (-)-NMS for the remaining (-)-[3H]QNB binding sites were observed. Therefore, there is no evidence for any differential regulation of either putative muscarinic receptor subtype in response to cholinergic deafferentation or as a function of the natural aging process.
尽管在大鼠基底核损伤后，其大脑皮层中胆碱乙酰转移酶（ChAT）的活性下降了34%，但拮抗剂配体[3H]喹核醇基苯甲酸酯（(-)-[3H]QNB）或(-)-[3H]N-甲基东莨菪碱（(-)-[3H]NMS）的Bmax并没有变化。此外，这种处理对与哌仑西平或(-)-NMS具有高亲和力和低亲和力的毒蕈碱受体的比例或亲和力没有产生显著影响。这些数据表明，假定的M2毒蕈碱受体并不局限于大鼠大脑皮层中含ChAT的神经元。与成熟大鼠相比，衰老大鼠的ChAT活性没有显著丧失，尽管观察到(-)-[3H]QNB和(-)-[3H]NMS结合的Bmax显著降低。然而，未观察到哌仑西平或(-)-NMS对剩余的(-)-[3H]QNB结合位点竞争的变化。因此，没有证据表明任何一种假定的毒蕈碱受体亚型在对胆碱能传入缺失的反应或作为自然衰老过程的函数方面存在差异调节。
