INDUCTION OF UTERINE LEUKOCYTOSIS AND ITS EFFECT ON PREGNANCY IN RATS

Glycogen, a leukocyte chemotactic agent, was used to induce transient leukocytosis in rat uteri during pregnancy. Large numbers of polymorphonuclear leukocytes (PMNLs) were attracted to the uterine endometrium and lumen after a single intrauterine injection of soluble glycogen (ligated horns) or glycogen-releasing gelatin beads (nonligated horns). Glycogen treatment on Days 3 through 5 of pregnancy (Day 5 = implantation) caused complete termination of pregnancy and significantly reduced fertility on Days 2 and 6 of pregnancy. However, fertility was unaffected by glycogen treatment after Day 6 of pregnancy even though a substantial leukocytic response was also elicited by glycogen in rats during later stages of gestation. This study indicates that glycogen-induced uterine leukocytosis effectively terminates pregnancy before and during the implantation stage. We propose that leukocyte chemotactic agents such as glycogen may prove clinically useful as abortifacient agents or may be used to improve the contraceptive efficiency of intrauterine devices.