Conditioned taste avoidance induced by Δ9-tetrahydrocannabinol in the Fischer (F344) and Lewis (LEW) rat strains

Abstract

Although Fischer (F344) and Lewis (LEW) rats differ in their sensitivity to the rewarding effects of ∆9-tetrahydrocannabinol (THC), no data have been reported on differences in their sensitivity to the drug's aversive effects, a limiting factor in drug use and abuse. Examining the degree of differences (if any) in such effects in these strains may help further characterize possible genetic factors important to abuse vulnerability. Accordingly, the aversive effects of THC (1–5.6mg/kg; intraperitoneal) were examined in 32F344 and 32 LEW subjects using the conditioned taste avoidance (CTA) procedure. Thermoregulation was assessed following an acute injection of THC (same as CTA groups) after a week washout period following the last trial. Subjects in both strains displayed dose-dependent THC-induced taste avoidance, with no significant strain difference. THC induced dose-dependent decreases in core body temperature in both strains. LEW subjects displayed lower core body temperatures than F344 rats, although this effect was independent of THC and was likely stress related. These results were discussed in terms of the nature of THC-induced taste avoidance and the basis of strain differences in the aversive effects of drugs of abuse.