C57BL/6J-bgJ (beige) mice: differential sensitivity in the tail flick test to centrally administered mu- and delta-opioid receptor agonists.
The antinociceptive effects of two mu-opioid receptor agonists, morphine and [D-Ala2, MePhe4, Gly-ol5]enkephalin (DAGO), and a selective delta-receptor agonist, [D-Pen2, L-Pen5]enkephalin (DPLPE), were determined in C57BL/6J-bgJ (beige) and control mice (CRS-CDl and C57BL/6By) using a standard tail-flick assay. The antinociceptive response of C57BL/6J-bgJ mice to intracerebro-ventricularly administered morphine and DAGO was significantly reduced compared to controls, but there was no difference in the antinociceptive response to DPLPE. These results suggest that there is a genetic deficit of mu-opioid receptor number or a genetically-induced alteration in receptor function in regions of C57BL/6J-bgJ brains involved in antinociception, that delta-opioid receptors can mediate antinociception in mice, and that the C57BL/6J-bgJ strain may offer a practical new animal model for studying the function of opioid receptor subtypes.
D000818:Animals; D004195:Disease Models, Animal / Q000503:physiopathology; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL / Q000235:genetics / Q000502:physiology; D008817:Mice, Mutant Strains / Q000235:genetics / Q000502:physiology*; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D010147:Pain Measurement; D011957:Receptors, Opioid / Q000172:deficiency / Q000187:drug effects* / Q000235:genetics; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu
D004745:Enkephalins; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009020:Morphine; D020881:Enkephalin, D-Penicillamine (2,5)-