Nebrisi Eslam El, Prytkova Tatiana, Lorke Dietrich Ernst, Howarth Luke, Alzaabi Asma Hassan, Yang Keun-Hang Susan, Howarth Frank C, Oz Murat
Department of Pharmacology, College of Medicine and Health Sciences, UAE University, Al Ain, United Arab Emirates.
Department of Pharmacology, Dubai Medical College, Dubai Medical University, Dubai, United Arab Emirates.
Front Pharmacol. 2020 Aug 31;11:1274. doi: 10.3389/fphar.2020.01274. eCollection 2020.
In this study, effects of capsaicin, an active ingredient of the capsicum plant, were investigated on human 5-hydroxytryptamine type 3 (5-HT) receptors. Capsaicin reversibly inhibited serotonin (5-HT)-induced currents recorded by two-electrode voltage clamp method in oocytes. The inhibition was time- and concentration-dependent with an IC = 62 μM. The effect of capsaicin was not altered in the presence of capsazepine, and by intracellular BAPTA injections or trans-membrane potential changes. In radio-ligand binding studies, capsaicin did not change the specific binding of the 5-HT antagonist [H]GR65630, indicating that it is a noncompetitive inhibitor of 5-HT receptor. In HEK-293 cells, capsaicin inhibited 5-HT receptor induced aequorin luminescence with an IC of 54 µM and inhibition was not reversed by increasing concentrations of 5-HT. In conclusion, the results indicate that capsaicin acts as a negative allosteric modulator of human 5-HT receptors.
在本研究中，对辣椒植物的活性成分辣椒素对人5-羟色胺3型（5-HT）受体的作用进行了研究。辣椒素可逆地抑制了通过双电极电压钳法在卵母细胞中记录的血清素（5-HT）诱导的电流。这种抑制作用具有时间和浓度依赖性，IC = 62 μM。在存在辣椒平的情况下，以及通过细胞内注射BAPTA或跨膜电位变化，辣椒素的作用均未改变。在放射性配体结合研究中，辣椒素未改变5-HT拮抗剂[H]GR65630的特异性结合，表明它是5-HT受体的非竞争性抑制剂。在HEK-293细胞中，辣椒素抑制5-HT受体诱导的水母发光蛋白发光，IC为54 µM，并且增加5-HT的浓度并不能逆转这种抑制作用。总之，结果表明辣椒素作为人5-HT受体的负性变构调节剂发挥作用。
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