Strain differences in patterns of drug-intake during prolonged access to cocaine self-administration.
The current study examined possible interactions between genetic factors and prolonged drug access by testing the Fischer (F344), Lewis (LEW), and Wistar rat strains in a prolonged access cocaine self-administration (SA) procedure. Before prolonged access, the strains did not differ in breakpoints for food or cocaine with progressive ratio (PR) testing. The LEW and Wistar rats acquired cocaine SA faster than the F344s. With prolonged access to cocaine SA, the LEW and Wistar rats showed comparable within-session patterns that were higher at the outset of each session and decreased to a stable baseline. Alternatively, the F344 rats began sessions with lower intake and increased their rate of intake during the session. The F344 and Wistar rats took more drug per session than the LEW rats but did not differ from each other. Following prolonged access, the strains did not differ in breakpoints for food, but the Wistar rats had higher breakpoints for cocaine than the F344 rats. Possible underpinnings for the observed strain differences are discussed.
Freeman
Kevin B
KB
Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, The University of Mississippi Medical Center, Jackson, Mississippi 39216, USA. kfreeman@psychiatry.umsmed.edu
Kearns
David N
DN
Kohut
Stephen J
SJ
Riley
Anthony L
AL
D000704:Analysis of Variance; D000818:Animals; D003042:Cocaine / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects* / Q000502:physiology*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D017208:Rats, Wistar; D012646:Self Administration; D013045:Species Specificity
D018765:Dopamine Uptake Inhibitors; D003042:Cocaine