THE RELATIONSHIP BETWEEN OVARIAN HORMONES AND UTERINE INFECTION IN THE RABBIT.

Abstract

SUMMARY The effect of ovarian hormones on the resistance of rabbits to experimental uterine infection was compared in oestrous and pseudopregnant animals and in ovariectomized rabbits treated with oestradiol (10 μg./day for 3 days) or progesterone (5 mg./day for 5 days) or oestradiol + progesterone. A standard period of 8 hr. following inoculation was used after which bacteria flushed from the uterus were assessed by plate count and leucocyte response by packed cell volume (p.c.v.). The number of bacteria recovered from the uterine horn of ovariectomized control animals was intermediate between, and significantly different from, pseudopregnant and oestrous animals. The results with ovarian hormone therapy in spayed animals were similar to those of pseudopregnant and oestrous condition. Flushing the uterus prior to inoculation significantly increased the p.c.v. of the uterus of groups under the influence of progesterone and decreased the number of bacteria in these groups. Thus flushing the uterus prior to infection reduced the significant differences in antibacterial activity due to hormone status. The mechanism of the effect of ovarian hormones on resistance to uterine infection is discussed, and it is postulated that a substance is present in the uterus of the rabbit under the influence of progesterone which inhibits leucocyte infiltration and therefore decreases the bactericidal effect.