Burke R E, Greenbaum D
J Neurochem. 1987 Aug;49(2):592-6. doi: 10.1111/j.1471-4159.1987.tb02904.x.
Although prior studies have supported the validity of measuring total muscarinic receptor binding in postmortem brain, there has not been a study of postmortem effects on muscarinic receptor subtypes, M1 and M2, defined by high and low affinity for pirenzepine, respectively. We have examined in rat brain the effect of postmortem delay at room temperature, storage at 4 degrees C and -20 degrees C, and multiple freeze/thaw cycles on total muscarinic binding, measured with [3H]quinuclidinylbenzilate ([3H]QNB) and on M1 muscarinic binding, measured with [3H]pirenzepine ([3H]Pir). We found that delay at room temperature up to 4 h, or storage at 4 degrees C for 24 h or at -20 degrees C for 4 weeks, or 3 freeze/thaw cycles had no effect on [3H]QNB or [3H]Pir binding. Exposure of brain to room temperature for 15 h, however, led to an increase in [3H]QNB binding, without change in [3H]Pir. Scatchard analysis showed an increase in binding sites without a change in affinity. We conclude that [3H]QNB and [3H]Pir are valid measures of total and M1 muscarinic binding, respectively, under these circumstances, but that caution must be used in the interpretation of indirect measures of M2 binding.
尽管先前的研究支持在死后大脑中测量总毒蕈碱受体结合的有效性，但尚未有关于死后对毒蕈碱受体亚型M1和M2影响的研究，M1和M2分别由对哌仑西平的高亲和力和低亲和力定义。我们已经在大鼠脑中研究了室温下死后延迟、4℃和-20℃储存以及多次冻融循环对用[3H]喹核醇基苯甲酸酯（[3H]QNB）测量的总毒蕈碱结合以及用[3H]哌仑西平（[3H]Pir）测量的M1毒蕈碱结合的影响。我们发现，室温下延迟长达4小时、4℃储存24小时或-20℃储存4周或3次冻融循环对[3H]QNB或[3H]Pir结合没有影响。然而，将大脑暴露于室温15小时会导致[3H]QNB结合增加，而[3H]Pir结合没有变化。Scatchard分析显示结合位点增加而亲和力没有变化。我们得出结论，在这些情况下，[3H]QNB和[3H]Pir分别是总毒蕈碱结合和M1毒蕈碱结合的有效测量指标，但在解释M2结合的间接测量指标时必须谨慎。
