[The neurochemical characteristics of the effect of morphine and pentapeptide FK 33-824 on cerebral cortical excitability].

GABA-stimulating agents (muscimol, depakine, aminohydroxyacetic acid), serotonin stimulants (5-hydroxytryptophan, fluoxetine), catecholaminergic stimulants (L-DOPA, apomorphine) and a cholinergic inhibitor (hemicholinium-3) of the brain were found to enhance the inhibitory effect of morphine and pentapeptide FK 33-824 on the cortical excitability of free-moving cats. GABA-negative agents (thiosemicarbazide, bicuculline, picrotoxin), serotonin-negative agents (p-chlorophenylalanine, methysergide), catecholaminergic inhibitors (6-hydroxydopamine, alpha-methyl-p-tyrosine) and cholinergic stimulant (physostigmine) of the brain appeared to decrease the effects of morphine and pentapeptide FK 33-824 on the excitability of the cortex. beta-adrenoceptor blocker propranolol decreased the effects of morphine and pentapeptide FK 33-824 on the cortical excitability, whereas alpha-adrenoblockers (phentolamine, phenoxybenzamine and yochimbine) exerted no effect on their action.