Role of Src family kinase in the rewarding effect and hyperlocomotion induced by morphine.

The aim of the present study was to investigate the effect of a selective Src family kinase inhibitor, 4-amino-5-(4-chlorophenyl)-(t-butyl)pyrazolo[3,4-D]pyrimidine (PP2), on the rewarding effect and hyperlocomotion induced by morphine. An intracerebroventricular pretreatment with PP2 (0.1-10 nmol/mouse) significantly suppressed the morphine-induced rewarding effect and hyperlocomotion in a dose-dependent manner. We also investigated the changes in immunoreactivities to phosphorylated-Src family kinase in the nucleus accumbens of mice showing the morphine-induced rewarding effect. We found for the first time that Src family kinase is activated in the nucleus accumbens of mice showing the morphine-induced rewarding effect as compared with that found in saline-treated control mice. These findings suggest that Src family kinases in the nucleus accumbens are involved in the rewarding effect and hyperlocomotion induced by morphine.