Substance P levels in the rat forebrain after apomorphine and haloperidol treatment

The content of substance P(SP) in the rat forebrain was assayed by radioimmunoassay technique after apomorphine and haloperidol injection. Apomorphine (1 and 10 mg/kg) produced dose-dependent decrease in SP content, while haloperidol, 0.2 and 1 mg/kg produced a marked increase in SP level in the forebrain. The results may suggest a modulatory role for SP in the action of dopamine receptor agonists and antagonists.