ALTERATIONS OF LIDOCAINE AND PENTYLENETETRAZOL-INDUCED CONVULSIONS BYMANIPULATION OF BRAIN MONOAMINES

The tresholds for pentylenetetrazol and lidocaine-induced clonic convu lsions were significantly influenced by manipulation of brain biogenic amines. Pretreatment with inhibitors of monoamine synthesis, alpha-me thyl-p-tyrosine and p-chlorophenylalanine, caused significant decrease s in brain monoamine contents and pentylenetetrazol seizure threshold, while the threshold for lidocaine-induced convulsions was significant ly increased by either treatment, Moreover, the inhibitor of dopamine- beta-hydroxylase, disulfiram, caused significant decrease in brain nor adrenaline (NA) and significant increase in brain dopamine (DA) conten ts. The threshold for pentylenetetrazol-induced convulsions was decrea sed by treatment with disulfiram, while that of lidocaine was increase d by the same treatment. Furthermore, treatment with L-dihydroxyphenyl alanine (L-DOPA) caused significant increase in brain DA contents, whi le 5-hydroxytryptophan (5-HTP) treatment caused significant increase i n brain 5-hydroxytryptamine (5-HT) contents, but the thresholds for li docaine and pentylenetetrazol-induced convulsions were not influenced by either treatment. These results may suggest that the brain monoamin ergic systems, different from their ability to inhibit control of pent ylenetetrazol seizures, act to potentiate lidocaine-induced convulsion s.