Pretreatment of either isoniazid, an aminoacid decarboxylase inhibitor, or GABA receptor antagonist picrotoxin prevented thedepressant effect of diazepam on the amplitude of phrenic discharge.
Conclusion: Melatonin does not exhibit its potentiation sleeping time in mice through melatonin 3 receptor. Hypnotic activity of melatonin may be mediated through picrotoxin site on GABAA receptor.