Age-dependent reduction in maximum electroshock convulsive threshold associated with decreased concentrations of brain monoamines.
This study investigated modification of the tonic convulsive threshold to maximum electroshock in 15- and 30 day old rats treated with drugs which reduce steady-state concentrations of monoamines. On postnatal day 15, reduction of central catecholamine concentrations by 6-hydroxydopamine or of central serotonin concentrations by 5,7-dihydroxytryptamine or p-chloroamphetamine did not alter the tonic convulsive threshold. However, simultaneous depletion of catecholamines and serotonin by tetrabenazine was associated with a significant decrease in the tonic threshold. This effect could be reversed partially by simultaneous administration of the catecholamine and serotonin precursors, L-dihydroxyphenylalanine and 5-hydroxytryptophan, respectively. On postnatal day 30, reduction of brain serotonin concentration, but not catecholamine concentrations, was associated with a significant decrease of the tonic convulsive threshold. In a previous study, in which 7-8 day old rats were used, a tetrabenazine-induced decrease in the tonic convulsive threshold prevented by L-dihydroxyphenylalanine but not 5-hydroxytryptophan. Furthermore, intracisternal 6-hydroxydopamine, but not 5,7-dihydroxyhyptamine, decreased the threshold on postnatal day 8. Therefore, the results of the present day study involving 15- and 30 day old rats, together with the earlier findings in 7-8 day old rats, [28] suggest an apparent developmental transition from catecholaminergic to serotonergic dominance in regulation of the tonic convulsive threshold during the first postnatal month.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000375:Aging; D000818:Animals; D001679:Biogenic Amines / Q000378:metabolism*; D001923:Brain Chemistry; D004597:Electroshock; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology; D007980:Levodopa / Q000494:pharmacology; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012640:Seizures / Q000503:physiopathology*; D013747:Tetrabenazine / Q000494:pharmacology; D010133:p-Chloroamphetamine / Q000494:pharmacology
D001679:Biogenic Amines; D006892:Hydroxydopamines; D015116:5,7-Dihydroxytryptamine; D007980:Levodopa; D010133:p-Chloroamphetamine; D006916:5-Hydroxytryptophan; D013747:Tetrabenazine