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本文报道了四氢异喹啉生物碱(TIQ):左旋千金藤啶碱(1—SPD),左旋及消旋四氢巴马汀(THP)及小檗胺(BBM)对大鼠脑内DA_2,5-HT_2及β—肾上腺素受体的结合特性。 所测的四种TIQ对β-肾上腺素受体的亲和力均很低(IC_(50)大于10~(-4)M)。结果表明,THP对单胺能神经递质受体亲和力远小于经典的单胺受体阻断剂,从而提示单胺受体阻断可能并非THP影响单胺能神经传递的主要机制。作者认为THP一类的TIQ,生物碱至少可以通过两种机制发挥作用:单胺受体阻断及利血平样“颗粒效应”。而对于THP,起主要作用的是引起单胺排空的“颗粒效应”。此外,实验中发现1-SPD与DA_2受体结合并不是简单的双分子反应,表现为1-SPD/[~3H]螺环哌啶酮抑制曲线的Hill系数远小于1。这一受体结合特点可能与其在动物行为实验中表现出的部分激动剂性质有关。
In this paper, the effects of tetrahydroisoquinoline alkaloids (TIQ) on the expression of DA_2 in rat brains were investigated by 1-SPD, THP and BBM. , 5-HT 2 and β-adrenoceptor binding properties. All four tested TIQs showed low affinity for β-adrenoceptors (IC 50 (> 10 -4) M). The results showed THP affinity to monoamine neurotransmitter receptors was much less than that of classical monoamine receptor blockers, suggesting that monoamine receptor blockade may not be the primary mechanism by which THP affects monoamine neurotransmission. The authors suggest that TIQ, a class of THP, alkaloids at least play a role in two mechanisms: blockade of monoamine receptors and reserpine-like “particle effects.” For THP, the primary effect is the “particle effect” that causes the monoamine to empty. In addition, it was found that the binding of 1-SPD to DA 2 receptor was not a simple bimolecular reaction, and the Hill coefficient of 1-SPD / [~ 3H] spiperone inhibition curve was much less than 1. This receptor binding characteristic may be related to its partial agonist properties exhibited in animal behavior experiments.