ABSTRACT
IDPH-791, when injected (ip) to mice potentiated the pentobarbitone sleeping time in a dose dependent manner. Involvement of neurotransmitters and receptors in this effect was studied using various receptor blockers, enzyme inhibitors, agonist and an amine depletor. Pretreatment with high dose of yohimbine (0.5 mg/kg), haloperidol, cyproheptadine, atropine and a combination of atropine and yohimbine significantly reversed the activity. Physostigmine, diethyldithiocarbamate and high dose of apomorphine (2.5 mg/kg) potentiated the subminimal effect of IDPH-791, whereas low dose of apomorphine (0.1 mg/kg) failed to potentiate. However, reserpine significantly reversed this response. Prazosin, phenoxybenzamine, low dose of yohimbine (0.25 mg/kg), propranolol, methysergide, mepyramine and cimetidine did not produce any change, thus ruling out the involvement of adrenergic, serotonergic and histaminergic systems. There seems to be simultaneous involvement of muscarinic receptors and postsynaptic dopamine (D2) receptors in IDPH-791 induced potentiation of pentobarbitone hypnosis.