Curcumin potentiates the function of human ? 7 -nicotinic acetylcholine receptors expressed in SH-EP1 cells

Abstract

Effects of curcumin, a biologically active ingredient of turmeric, were tested on the Ca 2+ transients induced by the activation of ? 7 subunit of the human nicotinic acetylcholine (? 7 nACh) receptor expressed in SH-EP1 cells. Curcumin caused a significant potentiation of choline (1 mM)-induced Ca 2+ transients with an EC 50 value of 133 nM. The potentiating effect of curcumin was not observed in Ca 2+ transients induced by high K + (60 mM) containing solutions or activation of ? 4 ? 2 nACh receptors and the extent of curcumin potentiation was not altered in the presence of Ca 2+ channel antagonists nifedipine (1 ?M), verapamil (1 ?M), ?-conotoxin (1 ?M), and bepridil (10 ?M). Noticeably the effect of curcumin was not observed when curcumin and choline were co-applied without curcumin pre-incubation. The effect of curcumin on choline-induced Ca 2+ transients was not reversed by pre-incubation with inhibitors of protein C, A, and CaM kinases. Metabolites of curcumin such as tetrahydrocurcumin, demethylcurcumin, and didemethylcurcumin also caused potentiation of choline-induced Ca 2+ transients. Notably, specific binding of [ 125 I]-bungarotoxin was not altered in the presence of curcumin. Collectively, our results indicate that curcumin allosterically potentiate the function of the ?7-nACh receptor expressed in SH-EP1 cells. - 2018 Elsevier Ltd