Expression and activities of 11betaHSD enzymes in the testes and reproductive tracts of sexually immature male pigs

Endocrine disruptors and other inhibitors of 11β-hydroxysteroid dehydrogenase 1 and 2: Tissue-specific consequences of enzyme inhibition

Numerous chemicals in the environment have the ability to interact with the endocrine system. These compounds are called endocrine disruptors (EDs). Exposure to EDs represents one of the hypotheses for decreasing fertility, the increased risk of numerous cancers and obesity, metabolic syndrome and type 2 diabetes. There are various mechanisms of ED action, one of which is their interference in the action of 11β-hydroxysteroid dehydrogenase (11βHSD) that maintains a balance between active and inactive glucocorticoids on the intracellular level. This enzyme has two isoforms and is expressed in various tissues. Inhibition of 11βHSD in various tissues can have different consequences. In the case of EDs, the results of exposure are mainly adverse; on the other hand pharmaceutically developed inhibitors of 11βHSD type 1 are evaluated as an option for treating metabolic syndrome, as well as related diseases and depressive disorders. This review focuses on the effects of 11βHSD inhibitors in the testis, colon, adipose tissue, kidney, brain and placenta.

Effect of Luteolin on 11Beta-Hydroxysteroid Dehydrogenase in Rat Liver and Kidney

11Beta-hydroxysteroid dehydrogenase (11β-HSD) enzymes control the glucocorticoid (GC) signaling, which is essential in regulating homeostasis. Our previous study revealed that Eclipta prostrata (EP) affected the activity and expression of 11β-HSD enzymes which might improve the efficacy and reduce the adverse drug effects of glucocorticoid in patients undergoing combinational therapy. However, it is still unclear which composition of EP plays a major role and how it works. In this paper, we chose Luteolin which is one of the main ingredients of EP and evaluated its effect and metabolism in combination with prednisone. The effects of different concentrations of Luteolin extract on prednisone/prednisolone metabolism indicated the enzyme activity of 11β-HSD, so the production rate (pmol/min per mg protein) of metabolites was used to indicate enzyme activity. Furthermore, we explored the influence of Luteolin on gene and protein expressions of 11β-HSD I/II in rat liver and kidney tissue. Our results showed that oral administration of Luteolin significantly increased the gene and protein expressions of hepatic 11β-HSD I and renal 11β-HSD II, which may improve the efficacy and reduce the adverse drug effect of glucocorticoid in clinical application. A potential clinical value of Luteolin would also be indicated in combination therapy with prednisone for the treatment of nephrotic syndrome.

Pathways and genes involved in steroid hormone metabolism in male pigs: a review and update

This paper reviews state-of-the-art knowledge on steroid biosynthesis pathways in the pig and provides an updated characterization of the porcine genes involved in these pathways with particular focus on androgens, estrogens, and 16-androstenes. At least 21 different enzymes appear to be involved in these pathways in porcine tissues together with at least five cofactors. Until now, data on several porcine genes were scarce or confusing. We characterized the complete genomic and transcript sequences of the single porcine CYP11B gene. We analyzed the porcine AKR1 gene cluster and identified four AKR1C, one AKR1C like genes and one AKR1E2 gene. We provide evidence that porcine AKR1C genes are not orthologous to human AKR1C. A new nomenclature is thus needed for this gene family in the pig. Thirty-two genes are now described: transcript (30+2 characterized in this study) and genomic (complete: 18+1 and partial: 12+1) sequences are identified. However, despite increasing knowledge on steroid metabolism in the pig, there is still no explanation of why porcine testes can produce androstenone and epiandrosterone, but not dihydrotestosterone (DHT), which is also a reduced steroid.

Regulation of glucocorticoid metabolism in the boar testis and caput epididymidis by the gonadotrophin-cAMP signalling pathway

In target tissues, cortisol is metabolised by two 11β-hydroxysteroid dehydrogenase (11βHSD) isoenzymes, namely 11βHSD1 and 11βHSD2, both of which are co-expressed in the boar testis and reproductive tract. The present study has assessed whether cortisol-cortisone metabolism in boar testis and caput epididymidis can be regulated via the gonadotrophin-cAMP signalling pathway. 11βHSD activities were measured by using a radiometric conversion assay in static tissue culture. In both testis and caput epididymidis, the net reduction of cortisone but not the net oxidation of cortisol, was significantly decreased by luteinising hormone (by 53 ± 20% and 45 ± 9%, respectively, P < 0.05), forskolin (by 60 ± 7% and 57 ± 9%, respectively, P < 0.01) and 8-bromo-cAMP (by 54 ± 4% and 64 ± 1%, respectively, P < 0.01). This suppression of 11-ketosteroid reductase activity in the boar testis by forskolin could be attenuated by the protein kinase A (PKA) inhibitor, H89. Hence, within the boar testis and the caput epididymidis, the local actions of glucocorticoids are modulated by gonadotrophin-cAMP-PKA signalling via their selective effects on the reductase activity of 11βHSD.

Immunolocalisation of 11β-HSD-1 and -2, glucocorticoid receptor, mineralocorticoid receptor and Na+ K+-ATPase during the postnatal development of the rat epididymis

Glucocorticoids have been implicated in male reproductive function and 11β-HSD-1 and -2, the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR), all of which are known to modulate glucocorticoid action, have been localised in the adult rat epididymis, but their developmental expression has not been investigated. Na(+)K(+)-ATPase activity, responsible for sodium transport, is induced by both mineralocorticoids and glucocorticoids in the kidney and colon, and has been localised in epididymal epithelium. This study examined the immunolocalisation of 11β-HSD-1 and -2, GR, MR and Na(+)K(+)-ATPase in rat epididymal epithelium (n = 5) at postnatal days (pnd) 1, 7, 15, 28, 40, 60, 75 and 104, and relative mRNA expression of 11β-HSD-1 and -2, and GR at pre-puberty (pnd 28) and post-puberty (pnd 75). 11β-HSD-1, GR and MR were localised in the epididymal epithelium from pnd 1, and 11β-HSD-2 and Na(+)K(+)-ATPase reactivity from pnd 15. At pnd 28 there was maximal immunoreactivity for both the GR and MR and 11β-HSD-1 and -2. 11β-HSD-1 mRNA expression in the caput increased from pre- to post-puberty, whereas 11β-HSD-2 mRNA expression fell over the same period (P < 0.01). GR mRNA expression was similar at pre- and post-puberty in both caput and cauda. Developmental changes in expression of 11β-HSD-1 and -2 suggest that overall exposure of the epididymis to glucocorticoids increases post-puberty, but cell-specific expression of the 11β-HSD enzymes still provides a capacity for intricate local control of glucocorticoid exposure.

Glucocorticoid receptor in the rat epididymis: expression, cellular distribution and regulation by steroid hormones

Glucocorticoids regulate several physiological functions, including reproduction, in mammals. Curiously, little is known about glucocorticoid-induced effects on the epididymis, an androgen-dependent tissue with vital role on sperm maturation. Here, RT-PCR, Western blot and immunohistochemical studies were performed to evaluate expression, cellular distribution and hormonal regulation of glucocorticoid receptor (GR) along rat epididymis. The rat orthologue of human GRalpha (mRNA and protein) was detected in caput, corpus and cauda epididymis and immunolocalized in the nucleus and cytoplasm of different epididymal cells (epithelial, smooth muscle and interstitial cells) and nerve fibers. Changes in plasma glucocorticoid and androgen levels differentially regulated GR expression in caput and cauda epididymis by homologous and heterologous mechanisms. In vivo treatment with dexamethasone significantly changed the expression of glucocorticoid-responsive genes and induced ligand-dependent GR nuclear translocation in epithelial cells from epididymis, indicating that GR is fully active in this tissue. Heterologous regulation of androgen receptor expression by glucocorticoids was also demonstrated in cauda epididymis. Our results demonstrate that the epididymis is under glucocorticoid regulation, opening new insights into the roles of this hormone in male fertility.

Sequence and expression of 11beta-hydroxysteroid dehydrogenase type 1 cDNA cloned from pig testis

Pig 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 cDNA was cloned from neonatal pig testis, and 15 nucleotides were found to differ from the sequence in GenBank (Accession No. NM_214248). It was an exclusive clone obtained as pig 11beta-HSD type 1, and the sequence of 11beta-HSD type 1 cDNA cloned from pig liver was identical to that from testis. Amino acid sequence, deduced from cloned cDNA, also had a conserved triad of catalytically important Ser, Tyr and Lys residues for the short-chain dehydrogenase/reductase family, a membrane-spanning domain consisting of hydrophobic amino acid and a glycine motif in the cofactor binding region. The protein translated from this clone on expression in mammalian HEK293 cells exhibited oxo-reduction activity of cortisone and oxidation activity of cortisol. Furthermore, this oxo-reduction activity of cortisone was stimulated by co-expression of human H6PDH, while oxidation activity of cortisol was suppressed by H6PDH co-expression in HEK293 cells. Based on these results, the sequence of newly cloned cDNA is considered to correspond to an active enzyme form of pig 11beta-HSD type 1.