title: Differences in morphine reinforcement property in two inbred rat strains: associations with cortical receptors, behavioral activity, analgesia and the cataleptic effects of morphine.
abstract: The purpose of the current study was to investigate genetic differences between two inbred strains of rats, Fisher-344 (F344/N) and Wistar Albino Glaxo (WAG/GSto), in a number of drug-naive and drug-related behaviors, including oral and intravenous morphine self-administration. F344/N and WAG/GSto rats differed in drug-naive behaviors such as nociception, rearing and sensitivity to lick suppression tests but did not differ in locomotor activity, ambulation or grooming behavior. F344/N rats were less sensitive to thermal stimuli as measured via tail-flick response, and more sensitive to the suppressive effects of intermittent shock in a lick suppression test. The F344/N rats demonstrated a significantly greater amount of rearing in open field tests but did not differ from WAG/GSto rats in locomotor activity, ambulation or grooming behavior. In addition to the behavioral results, naive F344/N and WAG/GSto rats were found to differ in mu and alpha 2 receptor concentrations (F344/N > WAG/GSto) and in 5HT2 and D2 affinity constants (WAG/GSto > F344/N). These two inbred rat strains also differed in drug-related behaviors. F344/N rats showed significantly greater depression of locomotor activity at morphine 3 mg/kg than WAG/GSto rats. In addition, F344/N rats consumed significantly greater amounts of morphine in a two-bottle choice procedure and morphine maintained significantly greater amounts of behavior during intravenous self-administration sessions. Importantly, drug maintained behavior was significantly greater than with vehicle only in the F344/N rats during operant self-administration sessions.
authors.affiliation: Laboratory of Experimental Therapy of Drug Abuse, All-Union Research Center of Addictions, Moscow, Russia.
authors.forename: S K
authors.initials: SK
authors.lastname: Sudakov
authors.forename: S R
authors.initials: SR
authors.lastname: Goldberg
authors.forename: E V
authors.initials: EV
authors.lastname: Borisova
authors.forename: L A
authors.initials: LA
authors.lastname: Surkova
authors.forename: I V
authors.initials: IV
authors.lastname: Turina
authors.lastname: Rusakov DJu
authors.forename: G I
authors.initials: GI
authors.lastname: Elmer
mesh_terms: D000284:Administration, Oral; D000698:Analgesia; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002375:Catalepsy / Q000139:chemically induced* / Q000523:psychology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D004361:Drug Tolerance; D004597:Electroshock; D005247:Feeding Behavior / Q000187:drug effects; D007275:Injections, Intravenous; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D011869:Radioligand Assay; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism*; D012054:Reinforcement, Psychology; D012646:Self Administration; D013045:Species Specificity
chemical_list: D011957:Receptors, Opioid; D009020:Morphine