Effect of p-chlorophenylalanine on LH, FSH, prolactin and ovulation in the rat

Abstract

The effect of p-chlorophenylalanine (PCPA: 300 mg/kg) on the rate of ovulation and plasma LH, FSH and prolactin secretion has been studied in rats at preovulatory periods (18th hour of diestrus) and post-ovulatory periods (9th hour of metaestrus).In both experimental groups, results showed that administration of PCPA caused an increase in both prolactin concentration and number of mature ovarian follicles (p less than 0.001).No changes were observed in FSH levels.LH concentration, however, decreased (p less than 0.001) and ovulation became totally inhibited.Rats treated at the 9th hour of metaestrus exhibited a marked luteinization as well as an increased number of corpus luteum in the ovaric tissue (p less than 0.001), whereas those treated at the 18th hour of diestrus underwent no luteinization and merely showed a greater number of mature ovarian follicles (p less than 0.001).PCPA, therefore, seems not to have a double effect on ovulation, LH, FSH, and prolactin secretion regardless of the pre or post-ovulatory periods.Changes observed in the ovaric tissue might be due to an increase in plasma prolactin concentration which appears earlier in the preovulatory than in the post-ovulatory treated animals.This difference may explain the double effect that has been attributed to the ovaric cycle and reproductive behavior.