D-Pen2-[D-Pen5]enkephalin impairs acquisition and enhances retention of a one-way active avoidance response in rats.
We reported previously that D-Pen2-[D-Pen5]enkephalin (DPDE), a delta-opioid receptor selective analog of Leu-enkephalin, impairs acquisition of an automated jump-up avoidance response in rats and acquisition of a one-way active avoidance response in mice. In the present study we investigated the effects of DPDPE on one-way avoidance conditioning in rats. The rats received two escape-only trials on day 1 and eight additional training trials on day 2. DPDPE (1.16 micrograms/kg IP) administered prior to training on day 2 impaired acquisition of the avoidance response. On the other hand, DPDPE (0.332 microgram/kg IP) administered following presentation of the two escape-only trials on day 1 significantly enhanced retention, as measured by improved one-way active avoidance performance on day 2. These results indicate that activation of delta-opioid receptors by DPDPE has a modulatory effect on acquisition and retention of aversively motivated performance.
Martinez
J L
JL
University of California, Department of Psychology, Berkeley 94720.
Hernandez
R V
RV
Rodriguez
S B
SB
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D004745:Enkephalins; D020881:Enkephalin, D-Penicillamine (2,5)-