RESUMO
We investigated the effect of hyperprolactinemia by long-term domperidone treatment (10.0 mg/kg, single daily dose, ip) on striatal dopamine (DA) receptor sensitivity in male Wistar rats weighing 250-300 g(N=8). Domperidone treatment for days continued to produce an increased in serum concentration of prolactin (PRL) form 17.3 ñ 2.2 to 33.1 ñ 7.3 and from 16.8 ñ 2.3 to 21.9 ñ 2.1, 2 and 72 h after domperidone withdrawal, respectively. Hyperprolactinemia induced by long-term domperidone treatment did not change binding sites (B max) and dissociation constant (Kd) of [3***H]-spiroperidol binding when compared to controls. These results show that byperprolactinemia induced by long-term domperidone treatment does not effect the sensitivity of striatal DA receptors presumably because the effect of neuroleptic drugs is due to their interaction with the receptors and not to the concomitant hyperprolactinemia