Contextual extinction of drug-associated discriminative stimuli fails to attenuate drug-vs-food choice in rhesus monkeys

Relapse within the context of a substance use disorder can be triggered by cues that function as discriminative stimuli to signal contingencies of drug availability and promote drug-taking behavior. Extinction procedures can weaken this association between drug-associated cues and drug-taking behavior and may reduce the probability of relapse. This study evaluated a regimen of extinction training on cocaine and heroin self-administration in rhesus monkeys under a drug-vs.-food choice procedure. Behavior was initially maintained under a concurrent schedule of food (1-g food pellets; fixed-ratio 100 schedule) and cocaine injections (0-0.1 mg/kg/injection; fixed-ratio 10) (n=4 males) or heroin injections (0-0.01 mg/kg/injection; fixed-ratio 10) (n=3 females and 1 male) during daily 2-h choice sessions. Subsequently, choice sessions were supplemented by daily 20-h extinction sessions for 14 consecutive days. During extinction sessions, drug-associated discriminative stimuli were presented, but responding produced saline injections. Drug continued to be available during choice sessions. Prior to extinction, both cocaine- and heroin-maintained dose-dependent increases in drug-vs.-food choice. Exposure to 14 extinction sessions failed to significantly decrease drug choice and increase food choice. These preclinical results do not support the effectiveness of extinguishing drug-associated discriminative stimuli as a non-pharmacological treatment strategy for reducing drug choice.