182 The Biochemistry of Semen 



not the anaerobic, fructolysis is gradually inhibited. Brochart (1951) 

 attributed this effect to adrenochrome and noradrenochrome which 

 are formed aerobically through the catalytic action of the cyto- 

 chrome system of bull spermatozoa upon adrenaline and noradren- 

 aline, respectively. Adrenochrome itself, added to bull semen in 

 amounts of 01-100 ^ag./ml, produces an instantaneous inhibition 

 of lactic acid formation but only so long as it remains in the oxidized 

 form; in the course of incubation with semen it becomes gradually 

 reduced and inactive. 



However, an alternative mechanism for the oxidation of seminal 

 adrenaline may well exist since Zeller and Joel (1941) have found 

 in extracts from the human prostate and seminal vesicle, but not in 

 the seminal plasma, a highly active monoamine oxidase (adrenaline 

 oxidase). The reaction catalysed by this enzyme follows the equation 



RCH^NR +O2+H2O -^ RCHO+NHR'+HaOa 

 and leads to the formation of hydrogen peroxide as one of the 

 reaction products. 



Pharmacodynamic properties 



An interesting synergistic relationship between adrenaline and 

 seminal plasma was reported by Goldblatt (1935Z)) who used 

 isolated seminal vesicles of the guinea-pig as his test object. He 

 observed that When he added 0-5-1 ml. human seminal plasma to the 

 medium (30 ml. oxygenated Tyrode solution) there was usually 

 no response from the vesicles; if, however, a small amount of 

 adrenaline was added first and a considerable interval of time 

 allowed to elapse until the only activity of the vesicle was an occa- 

 sional contraction, then the addition of the seminal plasma pro- 

 voked a succession of strong contractions. Adrenaline in doses so 

 small as to be entirely devoid of activity alone, nevertheless induced 

 in the vesicles a condition in which the seminal plasma itself or 

 material obtained from it by ethanolic or acetone extraction, were 

 able to develop to the full their pharmacological activity. This 

 behaviour of adrenaline led Goldblatt to suggest that there may be 

 a sort of synergism between adrenaline and the seminal plasma. 

 But it is not clear as yet, whether effects of this kind are significantly 

 related to the function of either the male or the female reproductive 

 system. 



