Figure 4.
GluR1 and GluR2/3 surface to intracellular ratios (S/I) are increased in cocaine-sensitized rats 21 d after the last injection, and the magnitude of S/I is positively correlated with the magnitude of sensitization. Data (mean ± SEM) are normalized to saline controls and represent the sum of two independent trials (see Fig. 2, B and D, for corresponding behavioral trial data). A, GluR1 S/I ratio (**p < 0.01 relative to saline and nonsensitized groups). B, GluR1 total protein levels (S + I, normalized to total protein in the lane). Non-Sens, Nonsensitized; Sens, sensitized. C, Relationship between the magnitude of behavioral sensitization (day 7/day 1 beam breaks; first 30 min of activity after cocaine injection) and the GluR1 S/I ratio for all cocaine-treated rats. Data represent the sum of two independent trials; r = Spearman rank order. D, GluR2/3 S/I ratio (**p < 0.01 relative to saline and nonsensitized groups). E, GluR2/3 total protein levels (S + I, normalized to total protein in the lane). Non-Sens, Nonsensitized; Sens, sensitized. F, Relationship between the magnitude of behavioral sensitization (day 7/day 1 beam breaks; first 30 min of activity after cocaine injection) and the GluR2/3 S/I ratio for all cocaine-treated rats. Data represent the sum of two independent trials; r = Spearman rank order. Saline, n = 18; all cocaine, n = 16; nonsensitized, n = 9; sensitized, n = 7.