[Right/left discrimination learning in rat pups neonatally treated with 6-hydroxydopamine].
At 2 and 4 days of age, rat pups were treated with 6-hydroxydopamine (6-OHDA; 70 micrograms, ivt) following desmethylimipramine (20 mg/kg, sc) pretreatment. Spontaneous activity test in a novel cage at 16 and 17 days of age revealed a sustained higher level of locomotor activity in 6-OHDA-treated rats, which was characterized by a deficit of habituation. For right/left discrimination learning trained from 18 days of age, "homing" was used as an reinforcer, i.e., pups could enter the goal area adjacent to home cage if they chose a predetermined correct arm of T-maze. Rats were trained 10 trials a day until they attained the learning criterion (at least 17 correct choices in 2 days). Thereafter, they were re-trained for the reversal learning to the criterion (at least 8 correct choices in a day). 6-OHDA-treated rats were required significantly more trials to attain the learning criterion both in the original and the reversal learnings. Biochemical assay confirmed a marked depletion of brain dopamine contents in striatum, cortex and midbrain with thalamus in 6-OHDA-treated rats. Therefore, the neonatal depletion of brain dopamine produced hyperactivity (habituation deficit) and a discrimination deficit during the developmental period.
Takasuna
M
M
Institute of Psychology, University of Tsukuba, Japan.
Iwasaki
T
T
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000378:metabolism; D004193:Discrimination Learning / Q000187:drug effects*; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006892:Hydroxydopamines / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D016627:Oxidopamine; D051381:Rats; D011916:Rats, Inbred F344
D006892:Hydroxydopamines; D016627:Oxidopamine; D004298:Dopamine