Possible role of dopamine in central effects of cocaine as measured by apomorphine gnawing test in mice.

Apomorphine (10mg/kg, s.c.) does not induce in mice a compulsion to gnaw, but pretreatment with cocaine (10-40 mg/kg, i.p.) caused gnawing activity. This effect of cocaine was inhibited by pretreatment with alpha-methyl-p-tyrosine, haloperidol, and physostigmine, but not with FLA-63, phenoxybenzamine and tetrabenazine. These findings would suggest that dopaminergic mechanism plays a significant role in the potentiation of apomorphine gnawing activity by cocaine and also support the view that inhibition of dopamine uptake is responsible for the stimulatory action of cocaine.