The effects of Pavlovian cue extinction and ceftriaxone on cocaine relapse after abstinence.

BACKGROUND: Cocaine use disorder is a significant public health problem and currently no medications are FDA-approved to reduce cocaine relapse. Drug-associated cues are reported to elicit craving and cocaine-seeking in humans. Repeated, non-reinforced presentations of drug-associated cues (cue extinction) have been proposed to reduce the ability of such cues to prompt drug-seeking. In rodent models of cocaine relapse, cue extinction reduces cocaine relapse when such extinction occurs in the same context as cocaine self-administration, which is not akin to the manner in which treatment would occur in humans. Here we sought to determine whether cue extinction outside of the cocaine self-administration context would reduce relapse in the drug context. We also hypothesized that ceftriaxone, an antibiotic consistently shown to attenuate cocaine relapse in rats, would enhance the relapse-preventing effects of cue extinction.
METHODS: Rats self-administered intravenous cocaine for 12 days followed by 20-21 days of abstinence. Immediately preceding the relapse test, rats either underwent 6 single daily cue extinction sessions (1 h/day) outside the self-administration context or no extinction with daily handling. Rats also received vehicle or ceftriaxone (200 mg/kg IP) on those six days.
RESULTS: Ceftriaxone attenuated cued relapse relative to vehicle-treated rats, but there was no additive effect of cue extinction on cocaine-seeking. Cue extinction alone did not attenuate relapse.
CONCLUSIONS: Thus, in agreement with work in humans, when cue extinction is conducted outside the drug-associated context it does not reduce the risk of relapse alone. Ceftriaxone remains a strong possibility for medication to reduce cocaine relapse in humans.