Differential effects of IV and IP muscimol on central dopamine metabolism.

The effect of IV and IP muscimol on the concentrations of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in both the nigrostriatal and mesolimbic dopaminergic pathways has been studied. IV muscimol (2 mg/kg), produced significant decreases in the concentration of DA in both DA systems, while the concentration of DOPAC remained unaltered. However, IP muscimol (5 and 10 mg/kg) caused significant increases in the concentrations of DA or DOPAC in all brain regions examined. Our results suggest differential actions of muscimol on DA metabolism dependent upon the route of administration.