Prenatal cocaine exposure markedly reduces mGluR1 association with G_q/11 and Homer1 in the FCX and hippocampus of P21 rats.

(A) The levels of G_q/11 and Homer1 associated with mGluR1s were examined in the immobilized anti-mGluR1 immunoprecipitates of the solubilized FCX and hippocampal synaptosomal membranes of prenatal saline- and cocaine-exposed P21 rats following incubation with Kreb’s-Ringer (K-R) or 1 µM glutamate by Western blotting. The representative Western blots show the detection of Gα_q/11 protein and Homer1 in the synaptosomal membranes prepared from FCX and hippocampus. Glutamate increased mGluR1 coupling to G_q/11 but not to Homer1. N = 4. (B) Quantitative data are presented as means ± s.e.m. of the ratios of optical intensity of indicated protein to the optical intensity of mGluR1 (1894.3±122.1–2068.8±348.3 optical intensity in FCX of saline and cocaine, respectively and 185.1±99.9–1885.5±98.3 optical intensity in hippocampi of saline and cocaine, respectively) to validate equal loading. Incubation with glutamate increased G_q/11 - mGluR1 coupling by 298.8±33.9% and 387.2±31.4% in FCX and hippocampus respectively. This glutamate-induced G_q/11-mGluR1 coupling was reduced by 69.0±12.3% and 63.4±3.2% respectively in FCX and hippocampus. Glutamate did not alter Homer1-mGluR1 coupling, whereas prenatal cocaine exposure reduced Homer1-mGluR1 association by 56.0±4.9–57.8±10.1% and 52.6±8.0–55.1±10.4% respectively in FCX and hippocampus. N = 4 for each group. *p<0.01, **p<0.05 comparing the level of Gαq/11 in K-R and 1 µM glutamate exposed brain synaptosomal membranes by two-tailed Student’s t test. #p<0.01 comparing the G_q/11 - mGluR1 or Homer1 - mGluR1 coupling levels in cocaine- to saline-treated groups by two-tailed Student’s t test.