Effect of subchronic treatment with methamphetamine on apomorphine-induced changes in locomotor activity in mice.

Subchronic treatment with methamphetamine (3 mg/kg, s.c., twice daily for 14 days) attenuated hypomotility produced by a low dose of apomorphine (0.1 mg/kg, s.c.) and enhanced hypermotility induced by a high dose of apomorphine (3 mg/kg, s.c.) in mice. The treatment did not affect apomorphine-induced decrease in striatal DOPA accumulation following gamma-butyrolactone plus m-hydroxybenzylhydrazine, an L-amino acid decarboxylase inhibitor, administration. These results suggest that drug sensitivity of presynaptic dopamine receptors in the striatum may not be altered after subchronic methamphetamine treatment.