Fig. 4. Activation or inhibition of Gβγ subunits alters amphetamine-induced extracellular dopamine (DA) levels in the nucleus accumbens of freely moving rats.

a Activation of Gβγ subunits increases amphetamine-induced extracellular DA levels in the nucleus accumbens (NAc). Data represented as percent increase of baseline extracellular DA levels per 10 min for rats treated with scr-mSIRK (1 mM)–amphetamine (3 mg/kg) (n = 4) or mSIRK (1 mM)–amphetamine (3 mg/kg) (n = 5) over 210 min of testing. scr-mSIRK or mSIRK was perfused through the microdialysis probe by reverse dialysis for 1 h (pretreatment period) before an intraperitoneal (i.p.) injection of amphetamine (3 mg/kg) (treatment period) and continually perfused through the 2 h treatment period. b Area under the curve (AUC) of total extracellular DA levels during the baseline, pretreatment, and treatment periods. c Inhibition of Gβγ subunits reduces amphetamine-induced extracellular dopamine levels in the NAc of freely moving rats. Data represented as percent increase of baseline extracellular DA levels per 10 min for rats treated with gallein (4 mg/kg)–saline (1 ml/kg) (n = 4), vehicle (25% dimethyl sulfoxide (DMSO) in saline)–amphetamine (3 mg/kg) (n = 7) or gallein–amphetamine (n = 7) over the 180 min testing period. The i.p. injections of vehicle or gallein occurred during the pretreatment period followed by an i.p. injection of amphetamine or saline during the 2 h treatment period. d AUC analysis of total extracellular DA levels during the baseline, pretreatment, and treatment periods. ***P < 0.001 denotes AUC between scr-mSIRK-amphetamine and mSIRK-amphetamine during the treatment period, ****p < 0.0001 denotes AUC between gallein-saline and vehicle-amphetamine during the treatment period, ^####p < 0.0001 denotes AUC between vehicle-amphetamine and gallein-amphetamine during the treatment period