Vasopressin effect on learning in 6-hydroxydopamine-pretreated rats: correlation with caudate vasopressin levels.

Conditioned avoidance learning was studied at 2 months of age in rats treated with intracisternal 6-OH dopamine (DA) at 5 days of life after desipramine pretreatment. Subcutaneous DDAVP 20 micrograms/rat or LVP 1 microgram/rat improved conditioned avoidance learning in the 6-OH DA-treated rats at least as much as in control rats. Caudate vasopressin levels significantly correlated with learning ability in the shuttle box in control rats (r = 0.69, n = 8), 6-OH DA-treated rats (r = 0.64, n = 8), 6-OH DA plus DDAVP-treated rats (r = 0.60, n = 9), or in the total sample (r = 0.59, n = 25, p less than 0.01).