Involvement of GABAergic system in regulation of the anxiolytic- and antidepressant-like effects of Scrophularia striata extract in rats

Abstract

Context: Neuropsychiatric disorders, like anxiety and depression, are global problems for clinical researchers in neurology. Recently, some authors have shown neuroprotective and anti-inflammatory effects of Scrophularia striata Boiss (Scrophulariaceae) extract in rodents. Objective: The purpose of the current study was to investigate the effects of S. striata extract on anxiety and depressant-like behaviors and find a possible mechanism for these impacts. Materials and methods: In this study, the elevated plus-maze (EPM) and forced swimming test (FST), which are useful models for selective identification of anxiolytic and antidepressant drug effects in rodents, were used. We investigated the effects of S. striata ethanol extract at different doses (20, 50, 100, 160 and 220 mg/kg) on anxiety and depression behaviors in the EPM and FST, and then we assessed the role of gamma-aminobutyric acid (GABA)(A) receptor in modulation of the effects of S. striata extract in the brain. Results: Our results showed that effective doses of S. striata (100 and 160 mg/kg) increased the percentages of open arm time and entries in the EPM and decreased immobility time in the FST in comparison with control group, indicating anxiolytic and antidepressant effects, respectively. Moreover, intracerebroventricular administration of GABA(A) receptor agonist (muscimol; 1 mu g/rat) enhanced the impact of S. striata, and GABA(A) receptor antagonist (bicuculline; 1 mu g/rat) blocked these effects in rats, indicating that significant interactions existed between S. striata and the GABAergic system in the brain. Discussion and conclusion: Findings of this study suggest that anxiolytic and antidepressant effects of S. striata may be modulated via the GABAergic system.