Inhibition of acetylcholine-mediated effects by borneol

• Published in: Biochemical pharmacology 2003, Vol.65 (1), p.83-90
• Main Authors: Park, Tae-Ju, Park, Yong-Soo, Lee, Tae-Gyun, Ha, Hyunjung, Kim, Kyong-Tai
• Format: Article
• Language: English
• Subjects: Acetylcholine - antagonists & inhibitors; Anesthetics, Local - pharmacology; Animals; Biological and medical sciences; Bornanes - pharmacology; Borneol; Bovine adrenal chromaffin cells; Calcium - metabolism; Cattle; Cholinergic system; Chromaffin Cells - drug effects; Chromaffin Cells - metabolism; Drug Interactions; Exocytosis; Lidocaine; Lidocaine - pharmacology; Medical sciences; Neuropharmacology; Neurotransmitters. Neurotransmission. Receptors; Nicotine - antagonists & inhibitors; Nicotine - pharmacology; Nicotinic acetylcholine receptor; Pharmacology. Drug treatments; Receptors, Nicotinic - drug effects; Receptors, Nicotinic - metabolism; Signal Transduction; Sodium - metabolism
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/S0006-2952(02)01444-2

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 μM. 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 μM), suggesting that the activity of nAChRs is inhibited by borneol. Borneol inhibited DMPP-induced secretion of [ 3 H ]norepinephrine with an ic 50 of 70±12 μM. Carbon-fiber amperometry also confirmed the inhibition of DMPP-induced exocytosis by borneol in single chromaffin cells. [ 3 H ]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.