Temporary Suppression of Estrous Cycles in the Rat by Prolactin

Abstract

Conclusions

In the regulation of the ovarian activity of rats prolactin is shown to be capable of playing a part, directly or indirectly. Prolactin can not be summarily omitted from lists of pituitary principles having action on the gonads of mammals. The suggestion of Dresel that lactation anestrus in mice is induced by prolactin is supported by these tests on mature non-parous rats. But under effective prolactin dosage the corpora of rats remain large, and at the age of 10-12 days their large cells show no clear evidence of degeneration. The failure of daily injections of low or moderate doses of progesterone to affect the estrous cycles of rats suggests that in this rodent, though the corpus luteum hormone plays its part, it is perhaps not the hormone primarily responsible for the anestrous of either gestation or lactation.