FACTORS ALTERING CONCENTRATION OF BLOOD LIPIDS 455 



increased, while a significant depression of the total serum cholesterol and 

 of the total cholesterol : lipid P ratio occurred in female patients. The 

 results obtained with diethylstilbestrol were similar to those obtained with 

 ethinyl estradiol. 638 



a'. The Effect of Natural Estrogenic Hormones and of Stilbestrol on 

 Chicks : Entenman and co-workers 639 were the first to demonstrate that the 

 injection of pregnant mare serum into immature female birds produced an 

 increase in blood lipids similar to that which had been observed earlier in 

 the domestic fowl, coincident with the laying of eggs. 294,640 Lorenz, Chai- 

 koff, and Entenman 295 subsequently showed that the injection of estrone 

 in a dosage of 3000 rat units caused a doubling of the blood lipids of the 

 immature female birds within twelve hours. Moreover, after the injec- 

 tion of 2000 rat units of estrone into male birds, blood lipid values well over 

 1000 milligram per cent were obtained. In contradistinction to the results 

 on women, all lipid constituents shared in the increase in the fowl, although 

 the most pronounced effect was exerted upon the neutral fat. In a later 

 study, Entenman et al. eil reported that the following crystalline estrogenic 

 substances increased the concentration of total fatty acids, phospholipids, 

 and cholesterol in the blood: estrone, estradiol, estradiol benzoate, and 

 ethinyl estradiol. The synthetic estrogenic compound, stilbestrol, was also 

 active and, in fact, increased the blood lipids to the greatest extent. Es- 

 tradiol benzoate resulted in a more marked increase than did any of the 

 other natural estrogenic substances investigated. The male hormone, 

 testosterone, as well as progesterone and DCA, yielded negative results 

 when administered in amounts as high as 60 mg. Flock and Bollman 53 

 confirmed the earlier results of Entenman and collaborators. 



In a study of the phospholipid response to estrogenic hormones and 

 stilbestrol, it was found that the increase in plasma phospholipid coincided 

 with a decrease of this component in the liver. 83 Since the liver is pre- 

 sumably the site of synthesis of the plasma phospholipids, Flock and Boll- 

 man 642 suggest that an increase in phospholipid synthesis may occur in 

 the liver. Burr and Barnes 643 suggest as an alternate explanation that the 

 estrogens may inhibit the destruction of phospholipids. As a result of 

 experiments with P 32 (injected intraperitoneally into cells), Flock and Boll- 

 man 642 came to the conclusion that the administration of diethylstilbestrol 



639 C. Entenman, F. W. Lorenz, and I. L. Chaikoff, J. Biol. Chem., 126, 133-139 

 (1938). 



640 F. W. Lorenz, I. L. Chaikoff, and C. Entenman, J. Biol. Chem., 128, 577-585 

 (1938). 



641 C. Entenman, F. W. Lorenz, and I. L. Chaikoff, J. Biol. Chem., 134, 495-504 (1940). 



642 E. V. Flock and J. L. Bollman, /. Biol. Chem., 156, 151-160 (1944). 



643 G. O. Burr and R. H. Barnes, Ann. Rev. Biochem., 12, 157-182 (1943). 



