title: Naloxone and [Met5]enkephalin effects on retention: attenuation by adrenal denervation.
abstract: This study investigated the effect of posttraining administration (i.p.) of naloxone and [Met5]enkephalin on retention in intact and adrenal-denervated mice. Naloxone (0.3 mg/kg) enhanced and [Met5]enkephalin (0.5 or 2.0 micrograms/kg) impaired retention in both inhibitory avoidance and Y-maze discrimination tasks. Further, [Met5]enkephalin antagonized the facilitative effect of naloxone on retention while naloxone attenuated the retention deficit produced by [Met5]enkephalin. However, neither naloxone nor [Met5]enkephalin affected retention in adrenal denervated mice. These findings suggest that endogenous hormones of the adrenal medulla, including [Met5]enkephalin, may be involved in the modulating influence of opiate peptides on memory storage.
mesh_terms: D000311:Adrenal Glands / Q000294:innervation*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D003714:Denervation; D004193:Discrimination Learning / Q000187:drug effects; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D008297:Male; D008568:Memory / Q000187:drug effects*; D051379:Mice; D009270:Naloxone / Q000494:pharmacology*
chemical_list: D009270:Naloxone; D004744:Enkephalin, Methionine