186 The Biochemistry of Semen 



Influence of male sex hormone 



There is a close relationship between the formation of citric acid 

 in the male accessory organs and the activity of the testicular 

 hormone (Humphrey and Mann, 1948, 1949). Following castration, 

 citric acid gradually disappears from the accessory gland secretions 

 but reappears on implantation or injection of testosterone. In this 

 respect, it behaves like seminal fructose, except, however, that in 

 some animals (e.g. rabbit) the postcastrate disappearance and the 

 hormone-induced reappearance of citric acid in the seminal plasma 

 is not as prompt as that of fructose. The 'citric acid test' which 

 depends on the relationship between the formation of citric acid and 

 androgenic activity, has been successfully used in conjunction with 

 the 'fructose test', for the study of certain endocrinological prob- 

 lems, such as the time relationship between spermatogenesis and 

 the onset of secretory function in male accessory organs (Mann, 

 Lutwak-Mann and Price, 1948; Mann, Davies and Humphrey, 

 1949; Mann, 1954); formation of citric acid in subcutaneous trans- 

 plants from accessory gland tissues (Lutwak-Mann, Mann and 

 Price, 1949); and determination of androgenic activity in ovarian 

 hormones (Price, Mann and Lutwak-Mann, 1949, 1954). 



In castrated rats, a direct relationship exists between the dose of 

 injected testosterone and the response of the seminal vesicle to 

 produce citric acid (Mann and Parsons, 1950). This makes it pos- 

 sible to utilize the determination of citric acid, like that of fruc- 

 tose, as a sensitive and quantitative assay of androgen (Mann and 

 Parsons, 1950). Removal of the hypophysis produces the same end- 

 result as castration and again, the secretion of citric acid by the 

 glandula vesicularis of a hypophysectomized rabbit can be restored, 

 in this case, either by testosterone or by gonadotrophin (Mann and 

 Parsons, 1950). The 'citric acid test' was also applied in studies 

 concerned with the influence of malnutrition on the composition 

 of semen (Lutwak-Mann and Mann, 1950^^, b, 1951; Mann and 

 Walton, 1953). The effect of malnutrition manifests itself in a pro- 

 gressive decline of the citric acid level in semen and accessory gland 

 secretion and is due to a state of so-called pseudo-hypophysectomy 

 (see p. 148). 



