Fig. 7. Cocaine-methiodide in cocaine-experienced rats induces enhanced Glu release: minute scale.

Cocaine-M injections in cocaine-experienced rats resulted in significantly different Glu (red)/Glu₀ (blue) currents for the first two injections at the minute scale (1: Glu/Glu₀ [gray bar, 56 min, F_1,14=7.03]; 2: Glu/Glu₀ (56 min, F_1,14=6.04), all p<0.03; 3: ns) showing [Glu] (orange, shaded area, duration of main effect, 1: 42 min, F_42,420=1.43; 2: 17 min, F_17,170=1.73; 3: 20 min, F_20,200=1.73, all p<0.03). Filled symbols are values significantly different from baseline. J summarizes mean (±SEM) increases in [Glu] across rats for the significant duration of drug effect, no differences within the cocaine-experienced group to cocaine-M injections (orange) were found (ns). Comparing Glu responses to the first two injections of cocaine-M in experienced rats, with acute cocaine-M (green) and cocaine (purple) revealed an Injection × Treatment interaction (F_2,25=4.46 p<0.03); the Glu response to the first cocaine-M injection in cocaine-experienced rats differed from that of rats receiving cocaine for the first time (white circle, F_2,27=3.45, p<0.05). While there was a locomotor response to cocaine-M in cocaine-experienced rats (shaded area, duration of main effect, 56 min all injections: 1: F_56,840=2.76; 2: F_56,840=2.04; 3: F_56,840=1.39, all injections p<0.05) this response did not differ across injections (K, ns). Cocaine and acute cocaine-M locomotion is shown for comparison.