Temporary increase in the circulating prolactin levels during and after consecutive administration of bromocriptine-mesilate (CB-154) in female mice

Abstract

Abstract. Changes in circulating prolactin (Prl) levels during and after consecutive administration of bromocriptine-mesilate (CB-154; 0.2 mg/day), a potent suppressor of pituitary Prl secretion, were studied in virgin mice of SHN and BALB/c strains. Plasma Prl levels were lower in CB-154-treated SHN mice than in vehicletreated controls until the first week of the daily treatment. However, the circulating Prl increased in the experimental mice and surpassed the control levels thereafter. The elevated levels of Prl were maintained throughout the treatment, then they decreased to control levels 1 month after the termination of the treatment. In BALB/c mice given CB-154, the pattern of changes of the circulating Prl levels was almost the same seen in SHN mice; a significant suppression of the Prl levels was observed on the 2nd day of the treatment and the levels increased and reached to the control levels thereafter. The results have demonstrated that in mice the inhibition of pituitary Prl secretion by CB-154 did not persist throughout the period of consecutive administration.