An Involvement of Endogenous Nitric Oxide (no) in the Mechanism of Action of Hypnotic and Convulsant Drugs

NO concentrations in the frontal cortex of anaesthetised rat were measured by using an electrochemical sensor, before and after intraperitoneal (i.p.) administration of a hypnotic drug, pentobarbital (20-40 mg/kg) or a convulsant agent, pentylenetetrazol (50 mg/kg). The results show that NO concentrations were decreased by pentobarbital, while pentylenetetrazole increased the NO levels. These data indicate that endogenous NO is involved in the mechanism of action of hypnotic and epileptic drugs. This further implicates a possible decrease of NO concentrations in the human brain following hypnotic or antiepileptic therapy and corresponding increase of the central NO during an epileptic attack or administration of excitatory amphetamine-like drugs. It is concluded that central NO is an important endogenous neuroexcitatory transmitter involved in the regulation of behavioural activity and seizure susceptibility.