Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center ''Kazan Scientific Center of RAS", Kazan, Russia, 2/31 Lobachevsky Street, box 30, Kazan, 420111, Russia.
Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center ''Kazan Scientific Center of RAS", Kazan, Russia, 2/31 Lobachevsky Street, box 30, Kazan, 420111, Russia; Institute of Neuroscience, Kazan State Medial University, Kazan, Russia, 49 Butlerova Street, Kazan, 420012, Russia.
Biochem Biophys Res Commun. 2020 Apr 9;524(3):589-594. doi: 10.1016/j.bbrc.2020.01.112. Epub 2020 Feb 3.
Previously, we found that muscarine downregulates the acetylcholine release at the frog neuromuscular junction acting via M3 muscarinic receptors. Here, the molecular mechanisms underlying the inhibitory effect of muscarine on the quantal secretion of acetylcholine were studied. Inhibition of phospholipase C (with U-73122) prevented the reduction of evoked neurotransmitter release induced by muscarine. Interruption of synthesis of phosphatidylinositol 3-phosphate by the inhibitor of phosphoinositide-3-kinase (wortmannin) did not affect the depressant action of muscarine but precluded the restoration of secretion after removal of muscarine from the bathing solution. The effect of muscarine was not significantly modified by the blockade of endocannabinoid receptors (with AM 281), but it was abolished by the inhibitor of nitric oxide synthase (L-NAME) as well as extracellular nitric oxide (NO) chelator (hemoglobin). Moreover, muscarine increased NO-sensitive dye fluorescence in junctional region, which was prevented by the M3 receptor antagonist 4-DAMP. The data obtained indicate that the attenuation of acetylcholine release mediated by muscarine is associated with a change in the activity of both lipid-metabolizing enzymes and NO synthases.
先前，我们发现毒蕈碱通过 M3 毒蕈碱受体下调蛙神经肌肉接头处的乙酰胆碱释放。在此，我们研究了毒蕈碱抑制乙酰胆碱量子分泌的抑制作用的分子机制。毒蕈碱引起的诱发神经递质释放减少被 PLC 抑制剂（U-73122）所抑制。PI3K 抑制剂（wortmannin）阻断磷脂酰肌醇 3-磷酸的合成并不影响毒蕈碱的抑制作用，但在从灌流液中去除毒蕈碱后，分泌的恢复受到阻碍。内源性大麻素受体阻断剂（AM 281）对毒蕈碱的作用没有显著影响，但一氧化氮合酶抑制剂（L-NAME）和细胞外一氧化氮（NO）螯合剂（血红蛋白）可完全消除毒蕈碱的作用。此外，毒蕈碱增加了连接区域中对 NO 敏感的染料荧光，而这种荧光可被 M3 受体拮抗剂 4-DAMP 所抑制。所得数据表明，毒蕈碱介导的乙酰胆碱释放的衰减与脂质代谢酶和一氧化氮合酶的活性变化有关。
