MIF-I's differential actions as an opiate antagonist.
The effects of MIF-I (Pro-Leu-Gly-NH2) were examined in three experimental conditions in which the opiate antagonist naloxone is active. MIF-I was found to block the analgesic effects of enkephalins and also morphine in the tail-flick test but not in the vas deferens assay. Unlike naloxone, MIF-I did not seem to reduce food intake in VMH-lesioned rats. The results suggest the possibility that MIF-I may represent a class of naturally occurring opiate antagonists with varying activities in independent situations.
D000700:Analgesics; D000818:Animals; D005247:Feeding Behavior / Q000187:drug effects; D007033:Hypothalamus, Middle / Q000502:physiology; D066298:In Vitro Techniques; D009075:MSH Release-Inhibiting Hormone / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists; D011930:Reaction Time / Q000187:drug effects
D000700:Analgesics; D009292:Narcotic Antagonists; D009270:Naloxone; D009075:MSH Release-Inhibiting Hormone