Des-Gly-vasopressin improves acquisition and slows extinction of autoshaped behavior

The effects of a vasopressin analog (DGAVP) with minimal endocrinological activity, were assayed on acquisition and extinction of a discrete trial, food reinforced, autoshaped lever touch response. Magazine-trained rats, maintained at 80-85% of free-feeding body weights, were injected s.c. with saline, 5 or 10 micrograms/kg of DGAVP 1 h before each of two sessions in which they learned to touch a retractable lever, presented on a 45 s random interval (RI 45) schedule. Retracted lever contacts (nose-pokes) and unconditioned rearing activity were simultaneously monitored. After acquisition of the extended lever touch response, rats were reassigned to treatment groups, and again injected with saline, 5 or 10 micrograms/kg of DGAVP 1 h before each of two extinction sessions. DGAVP facilitated acquisition (5 micrograms/kg) and slowed extinction (5 and 10 micrograms/kg) of conditioned behavior, while having no effects on the other behaviors, thus demonstrating the specificity of the effect of a vasopressin-like compound on both tasks (enhanced acquisition and retarded extinction) used to study learning.