Involvement of the GABA-Ergic System in Anxiolytic and Antidepressive Effects of the Scrophularia striata Extract in Rats

Abstract

Recently, neuroprotective and anti-inflammatory effects of an extract of Scrophularia striata Boiss (Sc. st., Scrophulariaceae) were shown in rodents. In our study, we investigated the effects of the Sc. st. extract on anxiety and depression-like behaviors in rats and tried to find possible mechanisms responsible for these influences. The elevated plus-maze (EPM) and forced swimming test (FST) were used. The ethanol extract of Sc. st. was perorally administered at different doses (20, 50, 100, 160, and 220 mg/kg). We also assessed interaction between the effective doses of Sc. st. and GABA(A) receptors in the brain. It was found that Sc. st. at doses of 100 and 160 mg/kg increased normalized values of the open arm time and number of entries in the EPM and decreased the immobility time in the FST in comparison with the control group, indicating anxiolytic and antidepression effects, respectively. Intracerebroventricular administrations of a GABA(A) receptor agonist, muscimol (0.5, 0.75, and 1 mu g/rat), enhanced the respective Sc. st. effects, while a GABA(A) receptor antagonist, bicuculline (0.5, 1 and 2 mu g/rat), blocked these effects. Thus, anxiolytic and antidepressive effects of the active components of Sc. st. may be mediated by modulation of the GABAergic system.