Inhibition of Estrous Cycle in the Rodent with Post-partum Urine and Commercial Prolactin

Abstract

In attempting to ascertain the effect of urine from lactating women upon mammary glands of rats and mice, it was observed that there was an inhibition of estrus in these animals. Animals with normally recurring estrus were used, and these had daily vaginal smears for at least 3 consecutive cycles as a means of control. Injections of post-partum urine were then started. It was found that at least oney usually 2, and occasionally 3 cycles were suppressed, after which the animal resumed its normal estrous rhythm in spite of continuation or increase in the amount of injected urine. Controls, injected with the urine of normal human males and females had no alteration of the rhythm. The rodent's ovaries during this period of induced diestrus contained active corpora lutea which were similar to the ovaries of lactating animals. If injections were discontinued during this period of induced diestrus, a vaginal smear indicative of estrus was obtained within 48 hours. These findings suggested that a substance, possi...