Dopamine D1 receptor mediation of the discriminative stimulus properties of SKF 38393.

Dopaminergic mediation of the stimulus properties of SKF 38393 was analyzed in a two-lever, drug discrimination task. After acquiring the ability to discriminate SKF 38393 (10 mg/kg) from saline, rats (N = 12) were given substitution (generalization) and combination (antagonism) tests with selective D1 and D2 receptor agonists and antagonists. The D2 agonists apomorphine and Ly 171555 (levo-isomer of Ly 141865) produced predominantly saline-lever responding; the D1 antagonist Sch 23390, but not the D2 antagonist haloperidol, dose dependently antagonized the SKF 38393 cue. These data support previous neurochemical and behavioral research which suggest that SKF 38393 may act by stimulating D1 receptors.