Immunolocalization of Steroidogenic Enzymes, P450scc, 3β-HSD, P450c17, and P450arom in the Hokkaido Brown Bear (Ursus arctos yesoensis) Testis

Tsubota, Toshio; Nitta, Hiroaki; Osawa, Yoshio; Ji, Mason; Kita, Isao; Tiba, Tosiro; Jm, Bahr

doi:10.1006/gcen.1993.1180

Cited by 62 publications

(44 citation statements)

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“…In support of this hypothesis, we found that testosterone, oestradiol and inhibin concentrations in dogs with seminomas were not significantly different from those in control dogs. The facts that aromatase has been demonstrated mainly in spermatids , Tsubota et al 1993 and that canine seminomas are believed to be of spermatocytic origin (Looijenga et al 1994) could explain the unaltered oestradiol concentrations found in this group of dogs.…”

Section: Discussionmentioning

confidence: 89%

“…Despite the fact that aromatase activity and thus the ability to synthesise oestrogens has been demonstrated in germinal cells of mice , bears (Tsubota et al 1993) and roosters (Kwon et al 1995), seminomas in dogs are believed not to secrete oestrogen and indeed are known to be hormonally inactive (Nielsen & Kennedy 1990, Chastain 1993. When signs of feminisation are present, they are probably due to a co-existing tumour that has not been detected (Nielsen & Kennedy 1990).…”

Section: Discussionmentioning

confidence: 99%

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Ageing, testicular tumours and the pituitary-testis axis in dogs

Peters

Jong²,

Teerds³

et al. 2000

Journal of Endocrinology

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Dogs of different ages without testicular diseases were evaluated to study possible age-related changes in hormone concentrations in serum. Dogs with testicular tumours were also investigated to study the relation between tumour type and hormone concentrations; in this study, dogs with Sertoli cell tumours, Leydig cell tumours and seminomas were included. We measured testosterone, oestradiol, LH, FSH and inhibin-like immunoreactivity concentrations in peripheral venous and testicular venous blood of these animals.In normal dogs there appeared to be no age-related changes in the concentrations of the investigated hormones, except for a significant age-related decrease in oestradiol concentrations in testicular venous blood (P<0·02). Dogs with a Sertoli cell tumour had greater oestradiol concentrations and inhibin-like immunoreactivity in both peripheral and testicular venous blood than did dogs without a neoplasm (P<0·05). Testosterone concentrations were reduced in dogs with Sertoli cell tumours, as were FSH and LH. Feminisation occurred in eight of 13 dogs with a Sertoli cell tumour and in two of 14 dogs with a Leydig cell tumour; it was accompanied by a significantly greater oestradiol concentration than in normal dogs and in dogs with Sertoli cell tumours without signs of feminisation. Dogs with a Leydig cell tumour had greater concentrations of oestradiol and inhibin-like immunoreactivity in both peripheral venous and testicular venous blood than did dogs without a neoplasm (P<0·05). The testosterone concentration in testicular venous blood of these dogs was lower than that in dogs with normal testes. The concentration of LH in peripheral venous blood was also reduced (P<0·05). Hormone concentrations in dogs with a seminoma were not different from those in normal dogs.It was concluded that seminomas are not endocrinologically active. In contrast, both Sertoli cell tumours and Leydig cell tumours can cause increased oestrogen production leading to signs of feminisation. These tumours also have considerable amounts of inhibin-like immunoreactivity, but only in Sertoli cell tumours does this result in a reduction in FSH concentrations, suggesting that Sertoli cell tumours secrete dimeric inhibin, whereas Leydig cell tumours presumably produce loose -subunits that cross-react in the inhibin assay but are not biologically active.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Ageing, testicular tumours and the pituitary-testis axis in dogs

Peters

Jong²,

Teerds³

et al. 2000

Journal of Endocrinology

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“…In mammals, it is now well established that germ cells represent a new source of oestrogens , Tsubota et al 1993, Levallet et al 1998, Carreau 2001. In adult human testis, aromatase has been immunolocalised to the cytoplasm surrounding elongated spermatids (Turner et al 2002) and in the cytoplasmic droplet of ejaculated spermatozoa (Rago et al 2003), but was absent from other germ cells (Turner et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Human immature germ cells and ejaculated spermatozoa contain aromatase and oestrogen receptors

Lambard¹,

Galeraud-Denis²,

Saunders³

et al. 2004

Journal of Molecular Endocrinology

122

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It is now well established that oestrogens play a part in germ cell function. These hormones are synthesised by the cytochrome P450 aromatase (P450 arom) and act via two kinds of receptor (ER and ER ). Although the presence of aromatase and oestrogen receptors in mammalian testis is now well documented, the localisation of these proteins in human germ cells is not yet clear. The primary purpose of the current study was to look for the expression of aromatase and oestrogen receptors in human germ cells. Human immature germ cells were collected from semen samples with an excess of rounds cells (>20%) and purified spermatozoa were obtained after sedimentation on a discontinuous PureSperm gradient. Expression of aromatase and oestrogen receptors was determined by RT-PCR with specific primers, and by Western blot using monoclonal antibodies. RT-PCR products for aromatase, ER and ER were amplified from total RNA isolated from human germ cells and spermatozoa. We identified an ER isoform variant that lacks exon 4 in human germ cells and visualised P450 arom as a single band of 49 kDa in germ cells, as we have already reported for human ejaculated spermatozoa. By Western blot, we identified two proteins for ER at ∼ 50 and ∼ 60 kDa, which could correspond to the long and short forms of ER formed from the use of alternative start sites. In human ejaculated spermatozoa, ER protein was not detected, even though we could amplify mRNA. Using Western blot analysis and a monoclonal antibody specific for ER , we detected two proteins in human immature germ cells: one of the expected size (66 kDa) and a second one of 46 kDa. In mature spermatozoa, only the 46 kDa band was observed and we speculate it may be related to the ER isoform lacking exon I. In conclusion, we have identified P450 arom and ER proteins (full-length and variant) in human germ cells. Further studies are now required to elucidate the mechanism of action of oestrogens on human male germ cells, in terms of both genomic and 'non-genomic' pathways.

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“…The present study demonstrated the localization of P450arom in spermatids in May, and April and June of the next year. It has been previously reported that developing spermatids and epididymal sperm contain P450arom [17,23,37,39]. In addition, it has been reported that estrogen receptors are present in the epididymis of the dog and monkey [41,43].…”

Section: Synthesis Of Estrogenmentioning

confidence: 99%