Ketamine blocks morphine-induced conditioned place preference and anxiety-like behaviors in mice
bioRxiv Preprint Server January 22, 2020 Greer McKendrick, Hannah Garrett, Holly E. Jones et al. 1 citation preprint
Mice conditioned with morphine showed anxiety-like behavior (less time in the open arms of an elevated plus maze) and robust conditioned place preference (CPP) for morphine. A single dose of (R,S)-ketamine given before testing increased open-arm time in both morphine- and saline-conditioned mice. A second ketamine injection before CPP tests blocked morphine-induced CPP, an effect lasting up to 28 days. Sucrose conditioning did not evoke anxiety but produced CPP, which ketamine also attenuated. These results suggest ketamine's blockade of morphine CPP may stem from impairing drug-context memory rather than solely reducing negative affective states.