MAINTENANCE OF PREGNANCY IN THE ABSENCE OF DIETARY PROTEIN WITH ESTRONE AND PROGESTERONE¹

Abstract

Nelson and Evans (1953a) have recently shown that institution of a protein-free diet the day of breeding in normal 80-day old rats resulted in 90–100% resorptions, with fetal death occurring in the majority of rats on the 9th or 10th days of gestation. The normality of reproductive performance in pair-fed controls receiving a 30% protein diet eliminated the factors of inanition or other dietary deficiencies as causes for these reproductive disturbances. The early appearance of vaginal eiythrocytes and the rapidity of the resorptive process in these defiqient rats together with the early loss of the estrous cycle in unbred rats suggested the possibility of hormonal deficiencies in these animals. Lyons (1943) has shown that the daily injection of 1 mg. estrone together with 3–4 mg. progesterone will maintain pregnancy in Itypophysectomized-oophorectomized rats. The same dosages of estrone and progesterone will also maintain pregnancy in vitamin B6-deficient rats (Nelson, Lyons and Evans, 1951).