Effects of 5α-dihydrotestosterone on the modulation of monocyte/macrophage response to Staphylococcus aureus: an in vitro study

BACKGROUND

Staphylococcus aureus (S. aureus) is a pathogen responsible for a wide range of clinical manifestations and potentially fatal conditions. There is a paucity of information on the influence of androgens in the immune response to S. aureus infection. In this study, we evaluated the influence of the hormone 5α-dihydrotestosterone (DHT) on mouse peritoneal macrophages (MPMs) and human peripheral blood monocytes (HPBMs) induced by S. aureus.

METHODS

An in vitro model of MPMs from BALB/c sham males, orchiectomised (OQX) males, and females was used. Cells were inoculated with 10 μL of S. aureus, phage-type 80 or sterile saline (control) for 6 h. The MPMs of OQX males and females were pre-treated with 100 μL of 10^-2 M DHT for 24 h before inoculation with S. aureus. The concentration of the cytokines TNF-α, IL-1α, IL-6, IL-8, and IL-10; total nitrites (NO^-2); and hydrogen peroxide (H₂O₂) were measured in the supernatant of MPM cultures. In addition, the toll-like receptor 2 (TLR2) and nuclear factor kappa B (NF-kB) genes that are involved in immune responses were analysed. For the in vitro model of HPBMs, nine men and nine women of childbearing age were selected and HPBMs were isolated from samples of the volunteers' peripheral blood. In women, blood was collected during the periovulatory period. The HPBMs were inoculated with S. aureus for 6 h and the supernatant was collected for the analysis of cytokines TNF-α, IL-6, IL-12; and GM-CSF, NO^-2, and H₂O₂. The HPBMs were then removed for the analysis of 84 genes involved in the host's response to bacterial infections by RT-PCR array. GraphPad was used for statistical analysis with a p value < 0.05.

RESULTS

Our data demonstrated that MPMs from sham males inoculated with S. aureus displayed higher concentrations of inflammatory cytokines and lower concentrations of IL-10, NO^-2, and H₂O₂ when compared with MPMs from OQX males and females. A similar result was observed in the HPBMs of men when compared with those of women. Previous treatment with DHT in women HPBMs increased the production of pro-inflammatory cytokines and decreased the levels of IL-10, NO^-2, and H₂O₂. The analysis of gene expression showed that DHT increased the activity of the TLR2 and NF-kB pathways in both MPMs and HPBMs.

CONCLUSIONS

We found that DHT acts as an inflammatory modulator in the monocyte/macrophage response induced by S. aureus and females exhibit a better immune defence response against this pathogen.

Establishing brown trout primary hepatocyte spheroids as a new alternative experimental model-Testing the effects of 5α-dihydrotestosterone on lipid pathways

Three-dimensional (3D) fish liver cultures mimic the in vivo cellular microenvironment, which is ideal for ecotoxicological research. Despite that, the application of these cultures to evaluate toxic effects in fish is scarce. A 3D model of brown trout (Salmo trutta f. fario) primary hepatocyte spheroids was optimized in this study by using DMEM/F-12 with 15 mM of HEPES, 10 mL/L of an antibiotic and antimycotic solution and FBS 10% (v/v), at 18 °C with ∼100 rpm. The selection of optimal conditions was based on a multiparametric characterization of the spheroids, including biometry, viability, microanatomy and immunohistochemistry. Biometric and morphologic stabilization of spheroids was reached within 12-16 days of culture. To our knowledge, this study is the first to culture and characterize viable spheroids from brown trout primary hepatocytes for over 30 days. Further, the 3D model was tested to explore the androgenic influences on lipidic target genes after 96 h exposures to control, solvent control, 10 and 100 µM of 5α-dihydrotestosterone (DHT), a non-aromatizable androgen. Spheroids exposed to 100 µM of DHT had decreased sphericity. DHT at 100 µM also significantly down-regulated Acox1-3I, PPARγ and fatty acid synthesis targets (i.e., ACC), and significantly up-regulated Fabp1. Acsl1 was significantly up-regulated after exposure to both 10 and 100 µM of DHT. The results support that DHT modulates distinct lipidic pathways in brown trout and show that this 3D model is a new valuable tool for physiological and toxicological mechanistic studies.

Regulatory role of dihydrotestosterone on BMP-6 receptors in granular cells of sheep antral follicles

Bone morphogenetic protein-6 (BMP-6) and dihydrotestosterone (DHT) affect steroid synthesis in follicles and regulate cell proliferation in the ovaries of female animals. However, little is known about granular cells (GCs) in sheep. We identified the key BMP-6 receptors, activin receptor-like kinase(ALK-6), and bone morphogenetic protein receptor type 2 (BMPRII) in sheep follicles using immunohistochemistry (IHC) and immunofluorescence (IF). Both ALK-6 and BMPRII were expressed in the GC layer, GC membranes, and cytoplasm. We evaluated ALK-6 and BMPRII expression at the follicular development stage using quantitative real-time PCR and western blotting to detect sheep GCs from large, medium, and small follicles (diameters of ≥5, 2-5, and ≤2 mm, respectively). The mRNA abundance and protein expression of ALK-6 and BMPRII were significantly higher in GCs from large follicles compared to those in GCs from small follicles (P < 0.05) and were the lowest in GCs from medium follicles. To assess whether DHT affects ALK-6 and BMPRII expression in sheep GCs, we cultured GCs from large follicles in vitro then incubated them with DHT (10^-11, 10^-9, 10^-7 M). We found that 10^-7-M DHT significantly inhibited ALK-6 and BMPRII mRNA and protein (P < 0.05). We further explored whether DHT regulates ALK-6 and BMPRII through the nuclear androgen receptor (AR) pathway and found that 10^-6-M flutamide, a non-selective androgen inhibitor, partially relieved the inhibitory effect of 10^-7-M DHT on ALK-6 and BMPRII expression. Thus, GCs in sheep antral follicles differentially expressed ALK-6 and BMPRII at various stages, indicating that BMP-6 plays different roles to some extent during the development of antral follicles, and that high concentrations of DHT can inhibit the expression of ALK-6 and BMPRII via the androgen receptor pathway in sheep GCs. The present study aimed to determine the expression of the main BMP-6-related main receptors, namely, ALK-6 and BMPRII, during the development of GCs in sheep antral follicles and a potential mechanism of DHT regulation in sheep GCs. Our findings lay a foundation for the further exploration of the effects of ovarian BMP-6 expression on follicular development.

Glucocorticoid signaling and lipid metabolism disturbances in the liver of rats treated with 5α-dihydrotestosterone in an animal model of polycystic ovary syndrome

PURPOSE

Polycystic ovary syndrome (PCOS) is a complex reproductive disorder often associated with obesity, insulin resistance, and dyslipidemia. Hormonal changes in PCOS may also include altered glucocorticoid signaling. Our aim was to examine whether alterations in hepatic glucocorticoid signaling are associated with disturbances of glucose and lipid metabolism in animal model of PCOS.

METHODS

Female rats, 3 weeks old, were subcutaneously implanted with 5α-dihydrotestosterone (DHT) or placebo pellets for 90 days to induce PCOS. Expression of 11β-hydroxysteroid dehydrogenase 1 (11βHSD1) and A-ring reductases (5α and 5β), as well as intracellular distribution of glucocorticoid receptor (GR) and expression of its regulated genes were examined in the liver. Proteins of hepatic lipid and carbohydrate metabolism and markers of inflammation were also assessed.

RESULTS

DHT treatment induced increase in body and liver mass, as well as in triglycerides and free fatty acids levels in plasma. Elevation of 11βHSD1 and reduction of 5α-reductase expression was observed together with increased hepatic corticosterone concentration and nuclear GR activation. Induced expression of Krüppel-like factor 15 and decreased expression of genes for proinflammatory cytokines and de novo lipogenesis (DNL) were detected in the liver of DHT-treated rats, while DNL regulators and proinflammatory markers were not changed. However, increased mRNA levels of stearoyl-CoA desaturase and apolipoprotein B were observed in DHT animals.

CONCLUSIONS

DHT treatment stimulated hepatic glucocorticoid prereceptor metabolism through increased corticosterone availability which is associated with enhanced GR activation. This does not affect gluconeogenesis and DNL, but could be linked to stimulated triglyceride synthesis and hypertriglyceridemia.

Derivatization with 2-hydrazino-1-methylpyridine enhances sensitivity of analysis of 5α-dihydrotestosterone in human plasma by liquid chromatography tandem mass spectrometry

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Quantitative analysis of low abundance androgens in human plasma.

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Quantitation of androgens over physiological range in men and post-menopausal women.

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Use of hydrazine derivatives improves analytical sensitivity.

Liquid Chromatography tandem mass spectrometry (LC-MS/MS) is the gold-standard approach for androgen analysis in biological fluids, superseding immunoassays in selectivity, particularly at low concentrations. While LC-MS/MS is established for analysis of testosterone and androstenedione, 5α-dihydrotestosterone (DHT) presents greater analytical challenges. DHT circulates at low nanomolar concentrations in men and lower in women, ionizing inefficiently and suffering from isobaric interference from other androgens. Even using current LC-MS/MS technology, large plasma volumes (>0.5 mL) are required for detection, undesirable clinically and unsuitable for animals. This study investigated derivatization approaches using hydrazine-based reagents to enhance ionization efficiency and sensitivity of analysis of DHT by LC-MS/MS. Derivatization of DHT using 2-hydrazino-1-methylpyridine (HMP) and 2-hydrazino-4-(trifluoromethyl)-pyrimidine (HTP) were compared. A method was validated using an UHPLC interfaced by electrospray with a triple quadruple mass spectrometer , analyzing human plasma (male and post-menopausal women) following solid-phase extraction. HMP derivatives were selected for validation affording greater sensitivity than those formed with HTP. HMP derivatives were detected by selected reaction monitoring (DHT-HMP m/z 396→108; testosterone-HMP m/z 394→108; androstenedione-HMP m/z 392→108). Chromatographic separation of androgen derivatives was optimized, carefully separating isobaric interferents and acceptable outputs for precision and trueness achieved following injection of 0.4 pg on column (approximately 34 pmol/L). HMP derivatives of all androgens tested could be detected in low plasma volumes: male (100 µL) and post-menopausal female (200 µL), and derivatives were stable over 30 days at -20°C. In conclusion, HMP derivatization, in conjunction with LC-MS/MS, is suitable for quantitative analysis of DHT, testosterone and androstenedione in low plasma volumes, offering advantages in sensitivity over current methodologies.

Physiological effects of 5α-dihydrotestosterone in male mummichog (Fundulus heteroclitus) are dose and time dependent

Numerous anthropogenic sources, such as pulp mill and sewage treatment effluents, contain androgenic endocrine disrupting compounds that alter the reproductive status of aquatic organisms. The current study injected adult male mummichog (Fundulus heteroclitus) with 0 (control), 1 pg/g, 1 ng/g or 1 μg/g body weight of the model androgen 5α-dihydrotestosterone (DHT) with the intent to induce a period of plasma sex hormone depression, a previously-observed effect of DHT in fish. A suite of gonadal steroidogenic genes were assessed during sex hormone depression and recovery. Fish were sampled 6, 12, 16, 18, 24, 30 and 36 h post-injection, and sections of testis tissue were either snap frozen immediately or incubated for 24 h at 18 °C to determine in vitro gonadal hormone production and then frozen. Plasma testosterone (T) and 11-ketotestosterone (11KT) were depressed beginning 24 h post-injection. At 36 h post-injection plasma T remained depressed while plasma 11KT had recovered. In snap frozen tissue there was a correlation between plasma sex hormone depression and downregulation of key steroidogenic genes including steroidogenic acute regulatory protein (star), cytochrome P450 17a1 (cyp17a1), 3β-hydroxysteroid dehydrogenase (3βhsd), 11β-hydroxysteroid dehydrogenase (11βhsd) and 17β-hydroxysteroid dehydrogenase (17βhsd). Similar to previous studies, 3βhsd was the first and most responsive gene during DHT exposure. Gene responses from in vitro tissue were more variable and included the upregulation of 3βhsd, 11βhsd and star during the period of hormone depression. The differential expression of steroidogenic genes from the in vitro testes compared to the snap frozen tissues may be due to the lack of regulators from the hypothalamo-pituitary-gonadal axis present in whole-animal systems. Due to these findings it is recommended to use snap frozen tissue, not post-incubation tissue from in vitro analysis, for gonadal steroidogenic gene expression to more accurately reflect in vivo responses.

Do 5α-Reductase Inhibitors Raise Circulating Serum Testosterone Levels? A Comprehensive Review and Meta-Analysis to Explaining Paradoxical Results

INTRODUCTION

Many studies have reported that 5α-reductase inhibitors (finasteride and dutasteride) raise serum testosterone (T) levels, yet there is lack of consistency among studies on this point.

AIM

To review and meta-analyze available studies reporting changes in serum T concentrations in men treated with 5α-reductase inhibitors (5α-RIs).

METHODS

A Medline search using PubMed and EMBASE was performed including the following key words: "finasteride," "dutasteride," "testosterone and 5α-reductases."

MAIN OUTCOME MEASURE

Relevant studies were extracted, evaluated, and analyzed. Of these, 40 studies were analyzed qualitatively and 11 were included in the meta-analysis. A random effects model was used to conduct the meta-analysis.

RESULTS

In 11 studies comprising 1,784 patients with age ranging between 18 and 83 years and average treatment follow-up of 17 months, meta-analytic estimate of the mean baseline change was 27 (95% confidence interval 1-54). The meta-analysis did not demonstrate unequivocal significant increase in serum T levels. The increase was not uniform among all studies reported. Sensitivity analysis showed that no single study contributed decisively to the outcome or could be attributed to drug action. The reported increases in T levels with finasteride or dutasteride in men with low baseline serum T may be attributed, in part, to increased trapping of T by unsaturated sex hormone binding globulin (SHBG) due to dissociation of 5α-dihydrotestosterone. In men with high baseline T levels, there appears to be no change in serum T levels. 10 studies reported luteinizing hormone, follicle-stimulating hormone, SHBG, and estradiol values and none reported significant changes in their levels, suggesting that observed changes in serum T levels are unlikely mediated by gonadotropins levels or peripheral conversion of T to estradiol.

CONCLUSION

5α-RI therapy is not associated with consistent and significant increases in serum T levels. Traish AM, Krakowsky Y, Doros G, et al. Do 5α-reductase inhibitors raise circulating serum testosterone levels? A comprehensive review and meta-analysis to explaining paradoxical results. Sex Med Rev 2019;7:95-114.

Antihypertensive effects of androgens in conscious, spontaneously hypertensive rats

Androgens are vasoactive steroids that induce acute vasodilation in a number of isolated vascular beds from different species, but the effects of these hormones on systemic blood pressure (BP) have been studied little. Although it has been reported that androgens exert systemic hypotensive effects through peripheral vasodilation in normotensive rats, there have not been any reports of systemic hypotensive effects of androgens in animals with hypertension. This study was designed to evaluate the acute effects of testosterone (TES) and its 5-reduced metabolites on systemic BP in hypertensive rats and to test the hypothesis that hypotestosteronemia may be involved in the pathogenesis of hypertension. Chronic, indwelling catheters were implanted in carotid artery and jugular vein of 18-21-week-old male spontaneously hypertensive rats (SHR) and normotensive-control Wistar-Kyoto (WKY) rats, for BP recording and drug administration, respectively. Bolus injections of TES, 5α- or 5β-dihydrotestosterone (5α- and 5β-DHT), were administrated cumulatively to conscious rats at doses of 0.1-100μmolkg^-1min^-1. 5β-DHT was also administrated during the pressor effect of Bay K 8644, an L-type voltage-operated Ca²⁺ channel (L-VOCC) agonist. In separate experiments, BP of orchidectomized normotensive male WKY and Wistar rats, with or without androgen-replacement therapy, was evaluated weekly for 10 weeks by tail-cuff plethysmography. TES and its metabolites reduced BP in a dose-dependent manner, while heart rate was reduced with some androgens at the highest doses. The hypotensive effects of androgens were markedly greater in SHR, with a rank order potency of: 5β-DHT>TES>5α-DHT. 5β-DHT, the most potent antihypertensive androgen, abolished the pressor response to Bay K 8644 in SHR. TES deprivation by orchidectomy increased BP in normotensive WKY and Wistar rats, but this hypertension was prevented by TES replacement therapy. BP responses to androgens are androgen structure-dependent. These data indicate that: 1) androgens play a significant role in the control of BP and may contribute to the pathogenesis of hypertension; 2) blockade of L-VOCC is involved in the antihypertensive effects of androgens, which are non-genomically mediated; and 3) hypotestosteronemia may be a risk factor for hypertension.

5α-Dihydrotestosterone enhances wound healing in diabetic rats

Wound healing involves a complex interaction between the cells, extracellular matrix and oxidative response.

AIMS

Analyze the effects of 5α-Dihydrotestosterone (5α-DTH) ointment in cutaneous wound healing by secondary intention in diabetic Wistar rats.

MAIN METHODS

Rats (302.23±26.23g, n=48) were maintained in cages with food and water ad libitum in accordance with the Guiding Principles in the Use of Animal Ethics Committee. Diabetes was induced by intraperitoneal injection of streptozotocin (60mg/kg). Three skin wounds (12mm diameter) were created on the animals' back, which were randomized into 6 groups according to the application received: VT group: Vehicle (lanolin), SA group: 0.9% saline solution, NC group: Non-diabetic, CP group: positive control (silver sulfadiazine 0001%), T1 group: Testosterone (10%), T2 group: Testosterone (20%) emulsified in lanolin. The applications were made daily within 21days, and tissues from different wounds were removed every 7days.

KEY FINDINGS

Both groups treated with testosterone (T1 and T2) showed a significantly higher proportion of type I and type III collagen fibers. Superoxide dismutase levels were significantly higher on days 7 and 14 in testosterone treated groups. Protein carbonyls and MDA were lower in both groups.

SIGNIFICANCE

We conclude that groups treated with 5α-DTH showed a better healing pattern with complete wound closure, and proved to have a positive effect on the morphology of the scar tissue as well as an antioxidant stimulating effect during secondhand intention skin wounds repair in diabetic rats.

Regulatory mechanisms for the development of the migratory phenotype: roles for photoperiod and the gonad

This article is part of a Special Issue "Energy Balance". Male white-crowned sparrows, Zonotrichia leucophrys gambelii, were studied to investigate roles of natural day length and the testes in regulating development and expression of the vernal migration phenotype. Previous work suggested that a pulse of androgen during winter months followed by the vernal increase in photoperiod promotes fueling (fat deposition) to support long distance flight; however, other traits required for successful migration remain untested. To investigate these points, birds were captured on their wintering grounds and castrated prior to winter solstice following Mattocks (1976). A subset of the castrates received 8mm Silastic implants of testosterone (T-castrates) and others blank implants (Blank-castrates) for 16 days in February. Shams were surgical controls. Migratory traits measured were as follows: 24h locomotor activity, prenuptial molt, body mass, fat score, flight muscle profile, cloacal protuberance (CPL) and plasma androgens measured over 28 weeks divided into 3 experimental periods (pre-implant, implant, and post-implant). Under short day lengths, castration increased diurnal locomotor activity over Shams. Testosterone implants temporarily enhanced CPL, plasma androgens and flight muscle enlargement, but failed to induce migratory restlessness. Whereas all groups exhibited seasonal increases in mass, fat score and muscle profile, only Shams showed timely onset and completion of prenuptial molt and migratory restlessness. Thus, for castrated males exposed to naturally increasing day lengths, the organizational effects of a transient testosterone surge were not sufficient to actuate a timely spring molt and migratory behavior. A fully functional testis that can organize central processes is required for the entire expression of the spring migratory phenotype.

Identification and quantification of 5α-dihydrotestosterone in the teleost fathead minnow (Pimephales promelas) by gas chromatography-tandem mass spectrometry

The steroid hormone 5α-dihydrotestosterone (DHT) is one of the most physiologically important androgens in male vertebrates, with the exception of teleost fish, in which it is generally assumed that DHT does not play any major physiological role. However, this assumption is challenged by the fact that all the components involved in DHT biosynthesis and action are present and evolutionary conserved in teleost fish. In fact, testosterone (T) is converted into DHT by two isoforms of the enzyme steroid-5-alpha-reductase (5αR), and both 5αRs gene expression and enzymatic activity have been detected in several tissues of different teleost species, which also have an androgen receptor with high binding affinity to DHT. This body of evidence strongly suggest that DHT is synthesised by teleost fish. We investigated this hypothesis using the cyprinid fathead minnow (Pimephales promelas) as the experimental model. The study of the evolutionary and functional conservation of 5αRs in teleost fish was used to support the experimental approach, based on an ultrasensitive gas chromatography-tandem mass spectrometry (GC-MS/MS) method to identify and measure simultaneously T and DHT in fathead minnow biological fluids and tissues. The analyses were performed using plasma samples collected from both male and female adult fish and samples of testicular tissue collected from sexually mature males. Both T and DHT were identified and quantified in all the samples analysed, and in particular, the high concentrations of DHT quantified in the testes suggested that these organs are a likely site of synthesis of DHT in the teleost fathead minnow, as they are in mammals. These results may represent the basis for future studies aimed at elucidating the physiological role, if any, of DHT in teleost fish.

Opposite long-term synaptic effects of 17β-estradiol and 5α-dihydrotestosterone and localization of their receptors in the medial vestibular nucleus of rats

In brainstem slices of male rats, we examined in single neurons of the medial vestibular nucleus (MVN) the effect of exogenous administration of estrogenic (17β-estradiol, E2) and androgenic (5α-dihydrotestosterone, DHT) steroids on the synaptic response to vestibular afferent stimulation. By whole cell patch clamp recordings we showed that E2 induced synaptic long-term potentiation (LTP) that was cancelled by the subsequent administration of DHT. Conversely, DHT induced synaptic long-term depression (LTD) that was partially reversed by E2. The electrophysiological findings were supported by immunohistochemical analysis showing the presence of estrogen (ER: α and β) and androgen receptors (AR) in the MVN neurons. We found that a large number of neurons were immunoreactive for ERα, ERβ, and AR and most of them co-localized ERβ and AR. We also showed the presence of P450-aromatase (ARO) in the MVN neurons, clearly proving that E2 can be locally synthesized in the MVN. On the whole, these results demonstrate a role of estrogenic and androgenic signals in modulating vestibular synaptic plasticity and suggest that the enhancement or depression of vestibular synaptic response may depend on the local conversion of T into E2 or DHT.