Deprenyl reduces serum prolactin concentrations in rats

The effects of i.v. administration of deprenyl (2.5, 5, and 10.0 mg/Kg body wt), a monoamine oxidase inhibitor, on serum prolactin (PRL) concentrations were investigated in female Sprague-Dawley rats. In the rats treated with the highest dose (10 mg/Kg), serum PRL decreased by 48% (p < 0.05) within 30 min and remained depressed during a 240-min period. Serum PRL concentrations also decreased by 38% (p < 0.05) within 30 min in the rats treated with the 5 mg dose and remained low during the remainder of the period of observation. Serum PRL levels showed no change in the group treated with 2.5 mg of deprenyl/Kg BW, except at 240 min when it was 48% (p < 0.05) below the pretreatment levels. In the control group, injected with the vehicle (0.5 ml saline) no decreases in PRL levels were observed. The average serum PRL concentrations during the entire posttreatment period were 45% above the pretreatment levels in the control group, whereas they were 31% and 43% below the respective pretreatment levels in the 5 and 10 mg groups, respectively. In the 2.5 mg group, the average serum PRL levels during the posttreatment period were not different from those in the pretreatment period. It is concluded that deprenyl is a potent inhibitor of PRL release in the rat.