The influence of intraperitoneally injected 6-hydroxydopamine on electroshock seizure in chicks and rats

1. 6-Hydroxydopamine, injected intraperitoneally in rats and chicks, did not induce spontaneous seizures but produced significant alterations in the threshold to electroshock seizure in chicks; the particular effects were dose-dependent and time-dependent. 2. Administration of 6-hydroxydopamine to 3 day old chicks and rats in the first and third days after birth resulted in an increase in the proportion exhibiting tonic seizure with electroshock when tested after 10-12 weeks. 3. When 6-hydroxydopamine was injected intraperitoneally into adult rats and cocks, there was no significant alteration in seizure threshold. 4. The results suggest that 6-hydroxydopamine penetrates the central nervous system of young chicks and rats and that adrenergic mechanisms are probably involved in modulating seizure mechanisms in both the chick and rat.