title: Leu-enkephalin impairs memory of an appetitive maze response in mice.
abstract: Leu-enkephalin (300 micrograms/kg) impaired memory of a Y-maze response in mice when the animals were trained to obtain food in one arm of the maze. The dose-response function was U-shaped, with neither 100 nor 600 micrograms/kg having any effect. Des-Tyr-Leu-enkephalin, a nonopioid peptide, had no effect at doses equimolar to the leu-enkephalin. Finally, the leu-enkephalin (300 micrograms/kg) was without effect if the drug injection was delayed 90 min. The results show that leu-enkephalin affects appetitive conditioning in much the same way as avoidance conditioning, a finding that suggests that leu-enkephalin may generally influence learning and memory.
mesh_terms: D000818:Animals; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology*; D016308:Enkephalin, Leucine-2-Alanine; D007858:Learning / Q000187:drug effects; D008297:Male; D008568:Memory / Q000187:drug effects*; D051379:Mice
chemical_list: D004743:Enkephalin, Leucine; C042087:enkephalin-Leu, des-Tyr(1)-; D016308:Enkephalin, Leucine-2-Alanine