EFFECTS OF HALOPERIDOL AND PROLACTIN SECRETING TUMORS ON CEREBROSPINAL-FLUID CONCENTRATIONS OF PROLACTIN IN THE FEMALE RAT

Studies were conducted to determine the effects of acute and chronic elevations in prolactin (PRL) secretion on serum and cerebrospinal fluid (CSF) PRL concentrations in the female rat. Young female rats showed a dose-dependent increase in serum and CSF PRL in response to haloperidol. A time-course evaluation of serum and CSF PRL levels after haloperidol indicated that serum PRL concentrations increased markedly by 30 min and declined thereafter; while CSF PRL increased more slowly, peaking at 2 to 8 h. In young rats with basal serum PRL levels, CSF PRL was maintained at 0.8 to 2.1% of serum PRL levels. During acute hyperprolactinemia, the CSF to serum PRL ratio increased to about 4%. During chronic severe hyperprolactinemia, induced by the growth of a MtT.W15 tumor, CSF PRL concentrations increased to 75 ng/ml, but this represented only 1.5% of serum PRL concentrations. Collectively, these data indicat that the blood-brain barrier effectively limits access to the brain of circulating PRL.