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Biochem Pharmacol. 2003 Jan 1;65(1):83-90.

Inhibition of acetylcholine-mediated effects by borneol.

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1
Department of Life Science, Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang, South Korea

Abstract

We previously reported that the aqueous extract from a medicinal plant Dryobalanops aromatica specifically inhibits the nicotinic acetylcholine receptor (nAChR) (Oh et al. Pharmacol Res 2000;42(6):559-64). Here, the effect of borneol, the main constituent of D. aromatica, on nAChR activity was investigated in bovine adrenal chromaffin cells. Borneol inhibited a nAChR agonist 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP)-induced calcium increase with a half maximal inhibitory concentration (IC(50)) of 56+/-9 microM. In contrast, borneol did not affect the calcium increases induced by high K+, veratridine, and bradykinin. The sodium increase induced by DMPP was also inhibited by borneol with similar potency (49+/-12 microM), suggesting that the activity of nAChRs is inhibited by borneol. Borneol inhibited DMPP-induced secretion of [3H]norepinephrine with an IC(50) of 70+/-12 microM. Carbon-fiber amperometry also confirmed the inhibition of DMPP-induced exocytosis by borneol in single chromaffin cells. [3H]nicotine binding, however, was not affected by borneol. The inhibitory effect by borneol is more potent than the effect by lidocaine, a commonly used local anesthetic. The data suggest that borneol specifically inhibits the nAChR-mediated effects in a noncompetitive way.

PMID:
12473382
[Indexed for MEDLINE]

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