Fig. 6.

Effect of acute cocaine on in vivophosphorylation of GluR1 at Ser⁸⁴⁵: comparison of wild-type and DARPP-32 knock-out mice. Wild-type or DARPP-32 knock-out mice were injected (intraperitoneally) with saline vehicle (Sal) or with (10 mg/kg) (A) or (20 mg/kg) (B) cocaine (Coc) and killed by focused microwave irradiation 30 min later. The levels of phospho-Ser⁸⁴⁵ GluR1 and phospho-Thr³⁴ DARPP-32 were detected in neostriatum by immunoblotting, and the data were quantitated by densitometry.Arrows indicate the position of phospho-GluR1 and phospho-DARPP-32 bands. A, Top, An autoradiogram of a representative experiment shows the level of phospho-GluR1 in saline-injected or cocaine-injected wild-type and DARPP-32 knock-out mice. The bar graph summarizes phospho-Ser⁸⁴⁵ GluR1 levels in the neostriatum of the wild-type and knock-out mice. Data are expressed as means ± SEM for eight mice per group (*p < 0.01 compared with saline-injected mice; Student's t test).A, Bottom, A typical autoradiogram shows the level of phospho-DARPP-32 in a saline-injected and a cocaine-injected wild-type mouse neostriatum. The bar graph shows phospho-Thr³⁴DARPP-32 levels in the neostriata of mice. Data are expressed as means± SEM for four mice per group (*p< 0.05 compared with saline-injected mice; Mann–WhitneyU test). B, Data are expressed as means± SEM for 3–5 mice per group (*p< 0.05 compared with respective saline-injected controls; Mann–Whitney U test).