Systemic administration of Met-enkephalin, (D-Ala2)-Met-enkephalin, beta-endorphin, and (D-Ala2)-beta-endorphin: effects on eating, drinking and activity measures in rats.
Rats were given four daily, interperitoneal injections (80 micrograms/kg) of Met-enkephalin, (D-Ala2)-Met-enkephalin-NH2, beta-endorphin, (D-Ala2)-beta-endorphin or the diluent (0.9% NaCl acidified to, 0.01 M with acetic acid). Animals were subsequently tested for food and water inake and activity. Met-enkephalin injections did not affect any of the measures but its (D-Ala2) analog reduced food intake and some of the activity measures in a complicated way. beta-Endorphin injections did not affect food or water intake; in familiar situations these animals were less active while novel situations seemed to potentiate activity. The (D-Ala2) analog reduced wheel running over 24 hours.
D000818:Animals; D004327:Drinking Behavior / Q000187:drug effects*; D004644:Emotions / Q000187:drug effects; D004723:Endorphins / Q000008:administration & dosage / Q000494:pharmacology*; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D005247:Feeding Behavior / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats
D004723:Endorphins; D004745:Enkephalins