Chunk #14 — DISCUSSION — Reduced MOPR expression in the NAc and/or VTA of G/G mice may contribute to decreased morphine-induced hyperactivity and locomotor sensitization
NAc and VTA were demonstrated to be involved morphine-induced hyperactivity in rats (Bunney et al., 1984). In addition, VTA plays an important role in morphine-induced locomotor sensitization (Kalivas and Duffy, 1987; Vezina et al., 1987). Our finding that G/G mice have lower MOPR expression in NAc and VTA than A/A mice is likely to contribute to the observation that G/G mice displayed decreased morphine-mediated hyperactivity and failed to develop locomotor sensitization following repeated morphine administration (Mague et al., 2009).
