title: Dose- and strain-dependent effects of dermorphin and [D-Ala2-D-Leu5]enkephalin on passive avoidance behavior in mice.
abstract: Dermorphin and [D-Ala2-D-Leu5]enkephalin, administered intracerebroventricularly (icv) immediately after training in a passive avoidance test, exerted dose- and strain-dependent effects in DBA/2 (DBA) and C57BL/6 (C57) mice. In fact, the peptides impaired, at a low dose (5 ng), the retention performances of both strains; a higher dose (50 ng) impaired retention in DBA but improved it in C57 mice. A dose of naloxone (0.3 microgram, icv), which was ineffective when administered alone, antagonized the effects observed. The results are discussed in terms of strain differences in central mechanisms.
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001921:Brain / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009270:Naloxone / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D018847:Opioid Peptides; D011957:Receptors, Opioid / Q000187:drug effects*; D013045:Species Specificity
chemical_list: D000701:Analgesics, Opioid; D009842:Oligopeptides; D018847:Opioid Peptides; D011957:Receptors, Opioid; C030058:dermorphin; D009270:Naloxone; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine