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 caud… Show more
“…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.…”
Section: Physiological and Pathological Roles Of Oestrogensmentioning
confidence: 92%
“…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).…”
Section: Introductionmentioning
confidence: 99%
“…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.…”
Section: Introductionmentioning
confidence: 99%
“…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.…”
The cytochrome P450 aromatase (P450arom) is the terminal enzyme responsible for the irreversible transformation of androgens into oestrogens and is present in the endoplasmic reticulum of various tissues throughout at least the phylum of vertebrates. The CYP 19 gene is unique and its expression is regulated in a tissue and more precisely in a cell-specific fashion via the alternative use of several promoters located in the first exons. The P450arom has been immunolocalized in germ cells of the mouse, brown bear and rooster. According to age, aromatase activity has been measured in immature and mature rat Leydig cells as well as in Sertoli cells, whereas in the pig, ram and human aromatase is mainly present in Leydig cells. In the adult rat testis, four complementary approaches (RTPCR, in situ hybridization, immunocytochemistry and the tritiated water assay) demonstrate that not only somatic cells but also mature germ cells represent a source of oestrogen synthesis. Taking into account the widespread distribution of oestrogen receptors (ER alpha & ER beta) in testicular cells and the genital tract of the male on the one hand, and the cross-talk between sex steroids and growth factors, and between membrane receptors and nuclear receptors for steroids on the other hand, it is anticipated that understanding of the pathophysiological roles of these 'female' hormones in the male will advance understanding of the hormonal regulation of male reproductive function. One of the future goals is to define oestrogen-targeted genes in the male gonad and indeed, a lot of work is now focused on this specific area in order to clarify the role of oestrogens in the reproductive tract of the male as well as to elucidate the regulation of aromatase gene expression.
“…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.…”
Section: Physiological and Pathological Roles Of Oestrogensmentioning
confidence: 92%
“…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).…”
Section: Introductionmentioning
confidence: 99%
“…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.…”
Section: Introductionmentioning
confidence: 99%
“…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.…”
The cytochrome P450 aromatase (P450arom) is the terminal enzyme responsible for the irreversible transformation of androgens into oestrogens and is present in the endoplasmic reticulum of various tissues throughout at least the phylum of vertebrates. The CYP 19 gene is unique and its expression is regulated in a tissue and more precisely in a cell-specific fashion via the alternative use of several promoters located in the first exons. The P450arom has been immunolocalized in germ cells of the mouse, brown bear and rooster. According to age, aromatase activity has been measured in immature and mature rat Leydig cells as well as in Sertoli cells, whereas in the pig, ram and human aromatase is mainly present in Leydig cells. In the adult rat testis, four complementary approaches (RTPCR, in situ hybridization, immunocytochemistry and the tritiated water assay) demonstrate that not only somatic cells but also mature germ cells represent a source of oestrogen synthesis. Taking into account the widespread distribution of oestrogen receptors (ER alpha & ER beta) in testicular cells and the genital tract of the male on the one hand, and the cross-talk between sex steroids and growth factors, and between membrane receptors and nuclear receptors for steroids on the other hand, it is anticipated that understanding of the pathophysiological roles of these 'female' hormones in the male will advance understanding of the hormonal regulation of male reproductive function. One of the future goals is to define oestrogen-targeted genes in the male gonad and indeed, a lot of work is now focused on this specific area in order to clarify the role of oestrogens in the reproductive tract of the male as well as to elucidate the regulation of aromatase gene expression.
“…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 ; …”
Summary. Concentrations of !4 androstenedione, testosterone and dihydrotestosterone were measured in the post-nuclear supernatant of the dog epididymis. In addition, they were measured in the efferent ducts and the testis. From the efferent ducts to the corpus there was a significant decrease in testosterone and 0 4 androstenedione concentrations. On the contrary, the concentration of dihydrotestosterone increased from the efferent ducts to the corpus where this steroid predominated. The marked differences in steroid concentration along the epididymis of the dog suggested regional differences in androgen metabolism.Introduction.
Recently we reported that mouse germ cells in the testis contain active P450 aromatase (P450arom), the enzyme that converts androgens to estrogens. This finding suggested that germ cells have the ability to produce estrogen. Further studies have shown that germ cells in the testis of several species contain P450arom. The goal of this study was to determine if epididymal sperm contain P450arom and if P450arom activity in sperm changes during traversion of the epididymis in the adult mouse. P450arom was localized in sperm present in the efferent ductules and epididymis by immunocytochemistry using an antiserum generated against purified human placental cytochrome P450arom. P450arom immunostaining in sperm was most prominent in sperm located in the proximal caput epididymis, decreased as sperm traversed the corpus epididymis, and was only slightly apparent in sperm in the cauda epididymis. The immunolocalization of P450arom in epididymal sperm was supported by the measurement of P450arom activity in sperm by the 3H2O assay. We found that P450arom activity in sperm significantly decreases as sperm traverse the epididymis. Based upon these observations, we conclude that sperm can synthesize estrogen and that the synthesis of estrogen by sperm present in the efferent ductules and caput epididymis could be important in the process of sperm maturation.
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