Prenatal cocaine exposure reduces RasGEF activity of GRASP-1 in the FCX.

<p>(<b>a</b>) RhoA and (<b>b</b>) Rap1 purified from frontal cortices (FCX) of naïve rats by immunoaffinity column were loaded with [³H]GDP and incubated with purified GRASP-1 from the FCX of prenatal cocaine- (dashed line) and saline- (bold line) treated P21 rat FCX. Aliquots of these two reactions were taken out every 30 sec up to 5 min and were filtered on HA filters. The [³H]GDP that remained on RhoA and Rap1 was measured by liquid scintillation counting. In GRASP-1 obtained from saline-treated FCX, [³H]GDP-loaded RhoA and Rap1 lost 76.7–81.3% of its radioactivity within 5 min, whereas only 62–69.7% of [³H]GDP was dissociated from RhoA and Rap1 by the GRASP-1 from prenatal cocaine-treated FCX. (<b>c</b>) The calculated GRASP-1 specific activity using RhoA and Rap1 as the substrate in FCX of prenatal saline- (blank bar) and cocaine- (solid bar) exposed P21 rats. *p<0.01 compared to saline-treated group using the respective substrate.