Studies on the biosynthesis in vivo and excretion of 16-unsaturated C19 steroids in the boar

Abstract

1. In one experiment [7alpha-(3)H]pregnenolone was infused continuously for 12min into the left spermatic artery of a sexually mature boar and blood was collected during this period by continuous drainage from the spermatic vein. After infusion, the testis was removed and immediately cooled to -196 degrees C. 2. From both the testicular tissue and the spermatic venous plasma, (3)H-labelled 16-unsaturated C(19) steroids were isolated and characterized and their radiochemical purity was established. 5alpha-Androst-16-en-3alpha- and 3beta-ol occurred mainly as sulphate conjugates and to a lesser extent as free steroids. Only traces of these alcohols occurred as glucosiduronate conjugates. 5alpha-Androst-16-en-3-one was found in the free (ether-extractable) fraction. 3. The isotope concentration of each of the (3)H-labelled 16-unsaturated C(19) steroids in testicular tissue was different from that in spermatic venous plasma. 4. The ratios of tritiated 5alpha-androst-16-en-3alpha- and 3beta-ol (free steroids) to their respective sulphate conjugates in the testicular tissue were less than the ratios of the same compounds in the spermatic venous plasma. The possibility that the sulphates are partially hydrolysed by testicular sulphatases before secretion is discussed. 5. In a second experiment, a continuous close-arterial infusion of [7alpha-(3)H]pregnenolone into the left testis was performed over a 200min period and all the urine that accumulated during the infusion was collected for analysis. 6. No (3)H-labelled 16-unsaturated C(19) steroids were detected in the urine as free steroids. Only a trace of 5alpha-androst-16-en-3alpha-ol was detected conjugated as glucosiduronate, whereas the corresponding 3beta-alcohol occurred mainly as glucosiduronate and to a lesser extent as sulphate. 7. The absence of 5alpha-androst-16-en-3beta-ol glucosiduronate in the spermatic venous blood and its presence in considerable amount in the urine may be attributed to hepatic glucuronyl transferase activity.

Changes With Age in the Occurrence of C19 Steroids in the Testis and Submaxillary Gland of the Boar

“…Furthermore, the change in the predominance of individual 16-androstenes that was found in the testis during development reflects the proposed biosynthetic pathway for these compounds (Brophy & Gower, 1972). The similar pattern in the occurrence of 3a-androstenol in both testis and submaxillary glands strongly suggests that the concentration of this steroid in the salivary gland is directly dependent upon the testicular production of this steroid or its precursors (Katkov, Booth & Gower, 1972); failure of the submaxillary gland to accumulate higher levels of 3/?-androstenol may be due to a limited presence of specific receptors for this steroid in the salivary gland, or to the inactivation and excretion of this steroid as the glucosiduronate conjugate in urine (Saat, Gower, Harrison & Heap, 1972).…”

Comparative rates of formation, in vivo, of 16-androstenes, testosterone and androstenedione in boar testis

“…Sterile operative procedures were used for catheterization of the arterial supply and the venous drainage of each testicle. For arterial catheters, the scrotal skin was incised to expose each testicle and the respective sper¬ matic artery was catheterized beneath the surface of the tunica albugínea as previously described (Saat et al 1972). Each testicle was repositioned in the scrotum after anchoring the catheter with silk sutures.…”

“…Further, the high capacity for forming the 16-androstenes (Gower, 1972;Claus, 1979;Booth, 1981) is of considerable interest because some of these steroids are important in the reproduc¬ tive physiology of the pig (Reed, Melrose & Patterson, 1974) and a cause of boar taint (Booth, 1982). There is little doubt that these steroids are quantitatively more important than the androgens (Ahmad & Gower, Previous work (Saat, Gower, Harrison & Heap, 1972) has shown that the spermatic venous blood plasma contains 3H-labelled 16-androstenes shortly after boar testes have been infused with [JH]pregnenolone. The aims of the present work were to study the rates of formation of some 16-androstenes relative to those of testosterone and 4-androstenedione.…”

A note on the metabolism of 5α-androst-16-en-3-one in the young boar in vivo

“…Indeed, few experiments have been devoted to the mechanisms by which circulating androstenone is stored in fatty tissue or to the pathways and intensity of its catabolism. In the mature boar, C 19 < l 16 steroids are probably catabolized in the liver (Claus, 1979 ;Fish et a/., 1980) and subsequently eliminated in the uterine, mainly in the form of an-!i glucuronide (Gower et al, 1970 a, b ;Saat et al, 1972Saat et al, , 1974. The purpose of ('&dquo;) Abbreviations and trivial names : an-a : 5a-androst- 16-en-3a-ol ; an-0 : 5u-androst-16-en-30-ol ; androstenone : 5a-androst-16-en-3-one ; pregnenolone : 5-pregnen-3(3-0l-20-one ; progesterone : 4-pregnen-3, 20-dione ; ( 3 H) androstenone : (5u-3 H) 5a-androst-16-ene-3-one. this experiment was to study the metabolism and excretion of circulating androstenone in the young boar weighing about 100 kg (common slaughter weight).…”