Developmental change in striatal concentration of homovanillic acid and 3,4-dihydroxyphenylacetic acid in response to apomorphine and haloperidol treatment.

The striatal concentration of homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) was estimated following an injection of apomorphine into the developing rat subchronically treated (S.C.) with haloperidol. At the withdrawal stage of haloperidol treatment, striatal HVA and DOPAC levels decreased in the rat aged 14, 24 and 34 days. The haloperidol treatment enhanced the apomorphine-induced reduction of the striatal HVA content at the withdrawal stage in the 24-day-old and 34-day-old rat. These results suggest that a functional link in the feedback control mechanism and dopamine receptors do not fully develop at birth but do so in the early stage of postnatal life.