Differential effects of alpha-methyl-p-tyrosine and 6-hydroxydopamine on pentylenetetrazol seizures in mice.

An intraperitoneal injection of the tyrosine hydroxylase inhibitor, alpha-methyl-p-tyrosine, did not alter the incidence of seizures induced by pentylenetetrazol, but increased the severity and duration of the tonic and clonic phases which resulted in death of some animals. By contrast, pentylenetetrazol seizures' characteristics were significantly changed in response to the intraperitoneal administration of the norepinephrine antagonist, 6-hydroxydopamine, by abolishing the tonic and clonic phases of the seizure. Moreover, alpha-methyl-p-tyrosine slightly attenuated the protective effect of 6-hydroxydopamine against pentylenetetrazol-induced seizures. Neurochemically, alpha-methyl-p-tyrosine significantly lowered the brain contents of both norepinephrine and dopamine while 6-hydroxydopamine caused no changes in the brain contents of these amines.