title: Intraventricular self-administration of leucine-enkephalin by laboratory rats.
abstract: Naive laboratory rats, without pre-exposure to operant training procedures or to opioids, were shown to self-administer directly into their cerebral ventricles the endogenous opiate peptide, leucine-enkephalin. They were shown to self-administer the peptide consistently for six consecutive days with no indication of the development of tolerance. The results indicate that leucine-enkephalin may possess potent reinforcing properties and suggests that it may play a role as an endogenous reward transmitter.
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004743:Enkephalin, Leucine / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D051381:Rats; D011919:Rats, Inbred Strains / Q000502:physiology*; D012054:Reinforcement, Psychology; D012646:Self Administration
chemical_list: D004743:Enkephalin, Leucine