Effects of hysterectomy, administration of uterine extract, posterior pituitary extract and aspirin on the length of pseudopregnancy in rats.

Effects of hysterectomy, administration of uterine extract, posterior pituitary extract and aspirin on the length of pseudopregnancy were investigated in 174 virgin, female rats. Pseudopregnancy was induced by injecting a single dose of reserpine (1 mg/kg body weight) subcutaneously on the 1st day of diestrus. The mean length of pseudopregnancy in the control group was 13.8 days. There was an increase (p less than .001) in the duration of pseudopregnancy to 17.1 days following hysterectomy. The administration of uterine extract reduced the duration to 15.9 days. Administration of posterior pituitary extract reduced the duration of pseudopregnancy in the pseudopregnant hysterectomized rats to 12.4 days (p less than .001). Aspirin treatment did not effect the length of pseudopregnancy. It is concluded that there is a definite pituitary-utero-ovarian relationship. The neurohypophyseal hormones may be involved in the mechanism of regression of corpora lutea of pseudopregnancy in rats.