FACTORS ALTERING CONCENTRATION OF BLOOD LIPIDS 403 



the rhythm in blood lipids disappeared in lues or after the menopause 

 served as an excellent control test. However, Peters and Van Slyke 202 

 do not accept these changes as being convincing in magnitude or in consist- 

 ency. 



Several workers have observed definite effects on blood lipids as a result 

 of the administration of sex hormones. Thus, Loeb 285 was able to demon- 

 strate a moderate increase in serum lipids when estradiol benzoate was 

 given to rats receiving a high fat diet which was devoid of essential fatty 

 acids. He later demonstrated that a storage of body fat followed the ad- 

 ministration of this hormone. 286 According to Bogdanovitch and Man, 287 

 the blood fatty acids of guinea pigs were increased not only by estrone but 

 also by antuitrin-S, which is an anterior pituitary gonadotrophic hormone. 

 These hormones produced no effect either on the blood cholesterol or on the 

 blood phospholipids. 



Schlegel 288 called attention to the interesting relationship between the 

 menstrual cycle and the serum choline concentration. Thus, the choline 

 level was found to reach the maximum value on the fourteenth day and the 

 lowest level on about the twenty-sixth day. It was deduced that a coin- 

 cidence obtains between the maxima and minima of the blood choline and 

 of the blood estrogen curves. It was suggested that the known effect of 

 estrogen upon the serum cholinesterase 289 in rats, rabbits, and guinea pigs 

 may provide an explanation for this relationship. In addition to the lunar 

 variation of blood choline, a seasonal one was also noted ; the choline con- 

 tent of the serum was found to be five times higher in February-March 

 than in June- July. 288 



f. The Effect of Ovulation. Since the ovulation process is intimately 

 connected with the sex cycle, it would seem probable that this might 

 likewise be associated with changes in the level of some of the blood lipids. 

 Studies in this field have been largely confined to fowls. 



Lawrence and Riddle 290 reported that the blood plasma of laying hens 

 contained more alcohol-soluble substances and phosphorus than did that of 

 non-laying hens or of males. The relative values of phosphorus were as 

 follows: males, 100, non-laying females, 115, and laying hens, 205. The 

 ratios of alcohol-soluble substances were 100, 116, and 181, respectively. 

 In the collared ring dove (Streptopelia risoria), an increase of 35% in the 



285 H. G. Loeb, Proc. Soc. Exptl. Biol. Med., 49, 340-342 (1942). 



286 H. G. Loeb, Proc. Soc. Exptl. Biol. Med., 51, 330-332 (1942). 



287 S. B. Bogdanovitch and E. B. Man, Am. J. Physiol, 122, 73-80 (1938). 



288 J. U. Schlegel, Am. J. Physiol, 158, 345-350 (1949). 



289 C. H. Sawyer and J. W. Everett, Am. J. Physiol, 148, 675-683 (1947). 



290 J. V. Lawrence and O. Riddle, Am. J. Physiol, 41, 430-437 (1916). 



