Figure 5.

Cocaine administration causes a loss of surface mGluR5. a, Single cocaine exposure did not change total NAc protein levels of mGluR5. Representative Western blots of animals administered saline (sham) or cocaine in vivo are shown. The blots demonstrate protein levels for mGluR5 using an mGluR5 antibody in the NAc 1 d after injection. Densitometry measurements are expressed as percentage of control ± SEM. Single cocaine exposure (n = 6) did not alter total mGluR5 protein levels in the NAc, compared with saline (n = 5; p > 0.05). b, Representative Western blots of animals administered in vivo with saline (sham) or cocaine showing biotinylated mGluR5 in the NAc 1 d after injection. Densitometry measurements are expressed as percentage of control ± SEM. Single cocaine exposure (n = 9) decreased biotinylated mGluR5 protein levels in the NAc, compared with saline (n = 8; ^***p < 0.05). c, Average time courses of mGluR5-mediated LTD. Single cocaine injection (n = 11) abolished mGluR5-LTD [compared with sham; n = 13; 40 min after application of the selective mGluR5 agonist (S)-DHPG (100 μm) for 10 min; p < 0.05]. Coc, Cocaine.