Effect of a Protein-Free Diet on Protein Metabolism in the Pregnant Rat

Abstract

Estrone (0.5 Mg) and progesterone (6.0 μg) daily prevent the abortive effects of a protein-free diet but do not restore protein synthesis to normal levels in pregnant, protein-deficient rats. Thus, serum total protein, albumin, α1-globulin and A/G values were lower in protein-deficient, steroid-maintained rats than in rats pair-fed 20 % casein. Alanine and aspartic transaminase in uterus, placenta and liver were not altered by steroids or diet during pregnancy. Uteri, placentas and livers of protein-deficient, steroid-maintained rats weighed less and contained less total RNA and protein than did those of pair-fed controls, but total DNA in uterus and liver was not altered. Uterine and hepatic nucleic acids, as well as serum proteins and A/G ratios, were comparable in protein-deficient rats which maintained pregnancy with and without exogenous ovarian steroids. However, placenta] weight and total nucleic acids were greater in protein-deficient, injected rats than in uninjected rats fed the same diet. Possible mechanisms by which estrone and progesterone maintain pregnancy in protein-deficient rats are discussed, and it is suggested that steroids may maintain pregnancy, in the absence of dietary protein, by sustaining placental function. (Endocrinology76: 454, 1965)