Effects of neonatal and adult 6-hydroxydopamine treatment on random-interval behavior.
Rats were given intraventricular injections of 6-hydroxydopamine (6-HDA) or saline-ascorbate vehicle as neonates (3-days old) and as adults (49 and 51 days old). At 73 days of age, they were trained on a random interval 90-sec schedule of water reinforcement. The rats treated with 6-HDA as adults stabilized at response rates approximately twice those of vehicle-treated rats, while rats treated with 6-HDA as neonates showed response rates which were not significantly different from vehicle-treated rats; Both L-Dopa and apomorphine decreased response rates at all doses tested. There were no differences among the groups with respect to the effect of these drugs. Adult-treated rats showed greater response rate decreases following peripheral decarboxylase inhibition with Ro 4-4602. Catecholamine analyses revealed the rats treated with 6-HDA as neonates had greater depletions in the striatum and the remainder of telencephalon than adult-treated rats but an increase in brainstem norepinephrine. These findings suggest that age of treatment is an important determinant of the biochemical and behavioral effects of treatment with 6-HDA.
D000375:Aging; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001058:Apomorphine / Q000494:pharmacology; D001923:Brain Chemistry / Q000187:drug effects; D002395:Catecholamines / Q000378:metabolism; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology*; D007980:Levodopa / Q000494:pharmacology; D008297:Male; D051379:Mice; D051381:Rats; D012055:Reinforcement Schedule; D013997:Time Factors
D002395:Catecholamines; D006892:Hydroxydopamines; D007980:Levodopa; D001058:Apomorphine