Protective effect of BR‐16A, a polyherbal preparation against social isolation stress: possible GABAergic mechanism

The antistress effects of BR-16A, a polyherbal preparation and its interaction with GABAergic modulators against social isolation-induced stress were investigated in the present study. Isolation stress was induced by keeping the mice (Laca strain) individually in each cage for 3 weeks and various drug treatments were given for a period of 5 days before the start of the experiments. The various behavioural parameters examined included pentobarbitone-induced sleep (sleep latency and duration), analgesia (tail-ssick test) and locomotor activity, respectively. BR-16A (100 mg/kg and 200 mg/kg) treatment for 5 days significantly reversed the social isolation stress-induced prolongation of onset and decrease in pentobarbitone-induced sleep, increased total motor activity and stress-induced antinociception. When diazepam (0.5 mg/kg), a benzodiazepine agonist, was co-administered with BR-16A (100 mg/kg), it significantly potentiated the reversal of pentobarbitone-induced shortening of sleep time effects; increased locomotor activity and stress induced antinociceptive effects. However, the sleep latency was not decreased significantly. Further, ssumazenil (2 mg/kg), a benzodiazepine receptor antagonist and FG 7142 (10 mg/kg), an inverse agonist, when co-administered with BR-16A (100 mg/kg), showed no significant reversal on pentobarbitone-induced hypnosis, locomotor activity and social isolation-induced antinociception compared with their effects per se. The present study demonstrated the antistress effects of BR-16A preparation against social isolation-induced stress. The present study also suggests that the GABAergic system may be involved in its antistress effect.