Effects of LY379268 and phenmetrazine alone on cocaine
self-administration. (A) Effects of the lower (0.03 mg/kg; green) and higher
(0.30 mg/kg; blue) doses of LY379268 relative to saline injection on increasing
doses of cocaine. (B) LY379268-induced decrease in breakpoints shown in Panel A
expressed as a percent of baseline. (C) Phenmetrazine minipumps (25 mg/kg/day;
gray bars) significantly reduced breakpoints at each dose of cocaine during
self-administration compared to saline minipumps. (D) Phenmetrazine-induced
(shaded area) reduction in breakpoint across three cocaine doses in Panel C
expressed as a percent of baseline. Number of animals: A, B (0.1875
mg/kg/infusion, n=12; 0.375 mg/kg/infusion, n=8; 0.75 mg/kg/infusion, n=6); C, D
(0.1875 mg/kg/infusion, n=6; 0.375 mg/kg/infusion, n=8; 0.75 mg/kg/infusion,
n=6). Main effect of treatment on cocaine self-administration:
δp<0.05,
δδδp<0.001. Post-hoc comparison of
LY379268 or phenmetrazine: *p< 0.05, **p<0.01,
***p<0.001 at 0.1875 mg/kg; #p<0.05,
##p<0.01,
###p<0.001 at 0.375 mg/kg
cocaine; Δp<0.05,
ΔΔp<0.01,
ΔΔΔp<0.001 at 0.75 mg/kg cocaine.
All doses of cocaine are mg/kg/infusion. Data points are expressed as
mean±SEM. Note: In panels A and C, bars are plotted for linear
breakpoints on left y-axis and corresponding final response ratios on log scale
are plotted on right y-axis for comparison.