Changes in Ratios of Phagocytotic Macrophages in the Splenic Adherent Cells during Estrous Cycle and Pseudopregnancy in Rats.

Abstract

We investigated changes in the ratio of phagocytotic cells (rPC) in splenic adherent cell population which were harvested from rats at different estrous cycle stages or during pseudopregnan-cy. rPC was assessed using the horse radish peroxidase intake as an index. Either the highest or lowest ratio was observed on the proestrous or the metestrous day during the course of estrous cycle. The highest ratio observed on the proestrous day decreased to 50% by ovariectomy on an antecedent diestrous day, and treatment with either 17β-estradiol or progesterone nullified this decrease. A decrease in rPC observed between the proestrous and estrous days was blocked by a dopamine agonist, CB-154 (150μg/rat), treatment on the proestrous day, and a simultaneous PRL treatment (25 μg/rat) counteracted this effect. The induction of pseudopregnancy by cervical stimulation on the proestrous day severely decreased rPC on 2 days later, and this decrease was completely inhibited by the treatment with CB-154. Thereafter rPC gradually increased toward the end of pseudopregnancy, but a high rPC observed at the end of pseudopregnancy (day 12) was significantly decreased by an ovariectomy one day before. These results indicate that rPC changes during estrous cycle and pseudopregnancy, and that this changes is induced at least by ovarian steroids and PRL.