Regional Differences in Steroidogenesis and Hormone Levels in the Epididymis and Vas Deferens of Adult Rats

Abstract

In vivo and in vitro studies with different parts of the epididymis and vas deferens were carried out to determine their inherent capacity to synthesize steroids and to correlate with the endogenous levels with or without the administration of hCG. Incubation with 14C-labelled pregnenolone and testosterone demonstrated that caput epididymidis was more active than other parts in synthesizing testosterone from 14C-pregnenolone and in converting labelled testosterone to 5 alpha-dihydrotestosterone (DHT). The cauda epididymidis and vas deferens accumulated more radioactivity in progesterone and dehydroepiandrosterone (DHEA) than the caput epididymidis. The levels of DHT, testosterone and 4-androstene-3, 17-dione in the caput epididymidis were reduced after ligation of ipselateral efferent ductules indicating the testicular origin of these steroids. The cauda epididymidis and vas deferens had higher levels of progesterone as compared to the other regions of the epididymis, which were decreased after the ligation. Intravenous injection of hCG increased the levels of oestradiol-17 beta in all tissues and markedly in the cauda epididymidis and vas deferens. The high levels of progesterone and oestradiol-17 beta present in these organs may be of importance in maintaining fertilizing ability of spermatozoa stored in the cauda epididymidis and vas deferens and their transport.

Sources of oestrogen in the testis and reproductive tract of the male

“…In relation to germ cell development, Tsubota et al (1997) have shown, in the brown bear, that oestradiol plays a role in the reinitiation of spermatogenesis after the beginning of testicular recrudescence (i.e according to seasonal changes) as has been speculated for the squirrel (Pudney et al, 1985). The data of Kumari et al (1980) showing an increase in concentration of oestradiol in the cauda epididymis and vas deferens suggested a possible role for oestrogens in the storage and transport of spermatozoa. All of these observations ®t with the data of Shetty et al (1997) demonstrating that oestrogens play an important role in spermatogenesis and spermiogenesis in the bonnet monkey.…”

“…injection of hCG increases the urinary concentration of oestrogens whereas castration causes a decrease). Indeed, in rete testis¯uid and in the caput epididymis of the rat, oestrogen concentrations are much higher than in blood (de Jong et al, 1973;Free & Jaffe, 1979;Kumari et al, 1980). Indeed, in rete testis¯uid and in the caput epididymis of the rat, oestrogen concentrations are much higher than in blood (de Jong et al, 1973;Free & Jaffe, 1979;Kumari et al, 1980).…”

“…In the mature rat, the low level of P450arom gene expression in Sertoli cells may be related to the well-established inhibition of aromatase activity by the neighbouring germ cells (Boitani et al, 1981;Le Magueresse & Je Âgou, 1986 3 ). No demonstration of the presence of an active P450arom in the epididymis of mice has been reported (Schleicher et al, 1989) although Kumari et al (1980) suggested that the adult rat cauda epididymis and vas deferens may express aromatase (under the indirect control of hCG) since their oestradiol contents were much higher than in blood.…”

“…The testicular source of oestradiol has been con®rmed in vitro by Baggett et al (1959) who demonstrated the conversion of labelled testosterone into oestrogens by stallion testicular pieces. Indeed, in rete testis¯uid and in the caput epididymis of the rat, oestrogen concentrations are much higher than in blood (de Jong et al, 1973;Free & Jaffe, 1979;Kumari et al, 1980). Moreover, in man the concentration of oestrogens in the spermatic vein is 50fold higher than in peripheral plasma (Hendry et al, 1983) therefore suggesting a testicular origin for these hormones.…”

Regional distribution of steroids in the dog epididymis

“…T was the major steroid in the testis, but its concentration in the epididymis appeared to be markedly reduced ; a significant decrease of T concentration was observed within the epididymis from the efferent ducts to the corpus. A 4 is a precursor of T, and rat and mouse epididymidis can produce T from its precursor (Hamilton, 1971 (Vreeburg, 1975 ;Kumari et al, 1980 ;Nishihara and Suzuki, 1980), rabbit (Frankel and Eik-Nes, 1970), bull and boar (Aafjes and Vreeburg, 1972 ;Ganjam and Amann, 19761 ; …”