Anxiolytic-like effects of xanthone-rich diethylether extract of Gentiana kochiana in rodents

Abstract

A diethylether extract of Gentiana kochiana aerial parts (GE), rich in two xanthones (gentiacaulein and gentiakochianin, 90% w/w), has already been shown to inhibit microsomal MAO enzymes in vitro and to exhibit certain antidepressant effects on mice. The aim of this study is to evaluate anxiolytic-like activity of GE in rodents by three behavioral tests, and to explore in vitro interactions of GE/xanthones with some anxiety-related elements of neurotransmission. The elevated plus maze test in rats and the staircase test in mice reveal specific anxiolytic-like influences of GE (5-20(40) mg/kg; ip), with the dose-effect ratios mainly converging to the inverted U-shaped curve. These effects are only partially analogous to the action of anxiolytic diazepam. In vitro assays demonstrate that neither GE nor the xanthones express substantial interactions with alpha(1)-adrenergic receptors, GABA(A) and GABA(B) receptors, and acetylcholine esterase. These results suggest a specific anxiolytic-like potential of GE in rodents and reduce the probability of particular neurochemical mechanisms to underlie this action.