Relative adrenal insufficiency in mice deficient in 5α-reductase 1

Bone marrow-derived mesenchymal stem cell ameliorates post-stroke enterobacterial translocation through liver-gut axis

BACKGROUND

Enterobacterial translocation is a leading contributor to fatal infection among patients with acute ischaemic stroke (AIS). Accumulative evidence suggests that mesenchymal stem cell (MSC) effectively ameliorates stroke outcomes. Whether MSC could inhibit post-stroke enterobacterial translocation remains elusive.

METHODS

Patients with AIS and healthy individuals were enrolled in the study. Mice subjected to transient middle cerebral artery occlusion were treated with bone marrow-derived MSC (BM-MSC) right after reperfusion. Enterobacterial translocation was evaluated with Stroke Dysbiosis Index and circulating endotoxin. Thickness of mucus was assessed with Alcian blue staining. Hepatic glucocorticoid (GC) metabolism was analysed with expression of HSD11B2, HSD11B1 and SRD5A1.

RESULTS

We report that the gut mucus layer was attenuated after the stroke leading to pronounced enterobacterial translocation. The attenuation of the gut mucus was attributed to diminished mucin production by goblet cells in response to the elevated systemic GC after cerebral ischaemia. Transferred-BM-MSC restored the mucus thickness, thus preserving gut microbiota homeostasis and preventing enterobacterial invasion. Mechanistically, the transferred-BM-MSC stationed in the liver and enhanced peroxisome proliferator-activated receptor γ signalling in hepatocytes. Consequently, expression of HSD11B2 and SRD5A1 was increased while HSD11B1 expression was downregulated which promoted GC catabolism and subsequently restored mucin production.

CONCLUSIONS

Our findings reveal that MSC transfer improves post-stroke gut barrier integrity and inhibits enterobacterial translocation by enhancing the hepatic GC metabolism thus representing a protective modulator of the liver-gut-brain axis in AIS.

Chronic Aroclor 1260 exposure alters the mouse liver proteome, selenoproteins, and metals in steatotic liver disease

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) continues to increase due in part to the obesity epidemic and to environmental exposures to metabolism disrupting chemicals. A single gavage exposure of male mice to Aroclor 1260 (Ar1260), an environmentally relevant mixture of non-dioxin-like polychlorinated biphenyls (PCBs), resulted in steatohepatitis and altered RNA modifications in selenocysteine tRNA 34 weeks post-exposure. Unbiased approaches identified the liver proteome, selenoproteins, and levels of 25 metals. Ar1260 altered the abundance of 128 proteins. Enrichment analysis of the liver Ar1260 proteome included glutathione metabolism and translation of selenoproteins. Hepatic glutathione peroxidase 4 (GPX4) and Selenoprotein O (SELENOO) were increased and Selenoprotein F (SELENOF), Selenoprotein S (SELENOS), Selenium binding protein 2 (SELENBP2) were decreased with Ar1260 exposure. Increased copper, selenium (Se), and zinc and reduced iron levels were detected. These data demonstrate that Ar1260 exposure alters the (seleno)proteome, Se, and metals in MASLD-associated pathways.

Pseudohypoadrenalism, a subclinical cortisol metabolism disorder in hyperuricemia

Background

Hyperuricemia is a known risk factor of lipid metabolism disorder. However, the mechanisms have not been fully understood.

Methods

The serum samples from hyperuricemia subjects were used to analyze the correlation between serum uric acid and clinical characteristics. Hyperuricemia mice induced by potassium oxonate (PO) and adenine were used to explore glucocorticoid metabolism.

Results

In hyperuricemia patients, the levels of serum uric acid were positively correlated with the levels of γ-glutamyltransferase, associated with a cortisol metabolism disorder. In hyperuricemia state, the adrenal glands failed to respond to adrenocorticotropic hormone properly, leading to low cortisol, but not corticosterone production, and decreased mRNA levels of aldosterone synthase, 11β-hydroxylase, and 3β-hydroxysteroid dehydrogenase 1, three key enzymes for cortisol synthesis. The expression of both hepatic 5α-reductase and renal 11β-hydroxysteroid dehydrogenase 2 was significantly reduced, which led to low cortisol clearance. We denominated this cortisol metabolism disorder in hyperuricemia as pseudohypoadrenalism (PHAL).

Conclusion

PHAL increased exposure to the bioavailable cortisol in the liver, leading to local amplification of the biological action of corticosteroids. Unregulated biosynthesis pathway of bile acid expanded bile acid pool, and further aggravated cholestatic liver injury.

Grape Polyphenols May Prevent High-Fat Diet-Induced Dampening of the Hypothalamic-Pituitary-Adrenal Axis in Male Mice

Context 

Chronic high-fat diet (HFD) consumption causes obesity associated with retention of bile acids (BAs) that suppress important regulatory axes, such as the hypothalamic-pituitary-adrenal axis (HPAA). HFD impairs nutrient sensing and energy balance due to a dampening of the HPAA and reduced production and peripheral metabolism of corticosterone (CORT).

Objective

We assessed whether proanthocyanidin-rich grape polyphenol (GP) extract can prevent HFD-induced energy imbalance and HPAA dysregulation.

Methods

Male C57BL6/J mice were fed HFD or HFD supplemented with 0.5% w/w GPs (HFD-GP) for 17 weeks.

Results

GP supplementation reduced body weight gain and liver fat while increasing circadian rhythms of energy expenditure and HPAA-regulating hormones, CORT, leptin, and PYY. GP-induced improvements were accompanied by reduced mRNA levels of Il6, Il1b, and Tnfa in ileal or hepatic tissues and lower cecal abundance of Firmicutes, including known BA metabolizers. GP-supplemented mice had lower concentrations of circulating BAs, including hydrophobic and HPAA-inhibiting BAs, but higher cecal levels of taurine-conjugated BAs antagonistic to farnesoid X receptor (FXR). Compared with HFD-fed mice, GP-supplemented mice had increased mRNA levels of hepatic Cyp7a1 and Cyp27a1, suggesting reduced FXR activation and more BA synthesis. GP-supplemented mice also had reduced hepatic Abcc3 and ileal Ibabp and Ostβ, indicative of less BA transfer into enterocytes and circulation. Relative to HFD-fed mice, CORT and BA metabolizing enzymes (Akr1d1 and Srd5a1) were increased, and Hsd11b1 was decreased in GP supplemented mice.

Conclusion

GPs may attenuate HFD-induced weight gain by improving hormonal control of the HPAA and inducing a BA profile with less cytotoxicity and HPAA inhibition, but greater FXR antagonism.

Mechanisms for establishment of GABA signaling in adrenal medullary chromaffin cells

γ-Aminobutyric acid (GABA) is thought to play a paracrine role in adrenal medullary chromaffin (AMC) cells. Comparative physiological and immunocytochemical approaches were used to address the issue of how the paracrine function of GABA in AMC cells is established. GABA_A receptor Cl^- channel activities in AMC cells of rats and mice, where corticosterone is the major glucocorticoid, were much smaller than those in AMC cells of guinea-pigs and cattle, where cortisol is the major. The extent of enhancement of GABA_A receptor α3 subunit expression in rat pheochromocytoma (PC12) cells by cortisol was larger than that by corticosterone in parallel with their glucocorticoid activities. Thus, the species difference in GABA_A receptor expression may be ascribed to a difference in glucocorticoid activity between corticosterone and cortisol. GABA_A receptor Cl^- channel activity in mouse AMC cells was enhanced by allopregnanolone, as noted with that in guinea-pig AMC cells, and the enzymes involved in allopregnanolone production were immunohistochemically detected in the zona fasciculata in both mice and guinea pigs. The expression of glutamic acid decarboxylase 67 (GAD67), one of the GABA synthesizing enzymes, increased after birth, whereas GABA_A receptors already developed at birth. Stimulation of pituitary adenylate cyclase-activating polypeptide (PACAP) receptors, but not nicotinic or muscarinic receptors, in PC12 cells, resulted in an increase in GAD67 expression in a protein-kinase A-dependent manner. The results indicate that glucocorticoid and PACAP are mainly responsible for the expressions of GABA_A receptors and GAD67 involved in GABA signaling in AMC cells, respectively.

Altered Cortisol Metabolism Increases Nocturnal Cortisol Bioavailability in Prepubertal Children With Type 1 Diabetes Mellitus

OBJECTIVE

Disturbances in the activity of the hypothalamus-pituitary-adrenal axis could lead to functional alterations in the brain of diabetes patients. In a later perspective of investigating the link between the activity of the hypothalamus-pituitary-adrenal axis and the developing brain in children with diabetes, we assessed here nocturnal cortisol metabolism in prepubertal children with type 1 diabetes mellitus (T1DM).

METHODS

Prepubertal patients (aged 6-12 years) diagnosed with T1DM at least 1 year previously were recruited, along with matched controls. Nocturnal urine samples were collected, with saliva samples taken at awakening and 30 minutes after awakening. All samples were collected at home over 5 consecutive days with no detectable nocturnal hypoglycaemia. The State-Trait Anxiety Inventory (trait scale only) and Child Depression Inventory were also completed. Glucocorticoid metabolites in the urine, salivary cortisol (sF) and cortisone (sE) were measured by liquid chromatography-tandem mass spectrometry. Metabolic data were analysed by logistic regression, adjusting for sex, age, BMI and trait anxiety score.

RESULTS

Urine glucocorticoid metabolites were significantly lower in T1DM patients compared to controls. 11β-hydroxysteroid dehydrogenase type 1 activity was significantly higher, while 11β-hydroxysteroid dehydrogenase type 2, 5(α+β)-reductase and 5α-reductase levels were all lower, in T1DM patients compared to controls. There was a significant group difference in delta sE level but not in delta sF level between the time of awakening and 30 minutes thereafter.

CONCLUSIONS

Our findings suggest that altered nocturnal cortisol metabolism and morning HPA axis hyperactivity in children with T1DM leads to greater cortisol bioavailability and lower cortisol production as a compensatory effect. This altered nocturnal glucocorticoid metabolism when cortisol production is physiologically reduced and this HPA axis hyperactivity question their impact on brain functioning.

Unravelling the role of epigenetics in reproductive adaptations to early-life environment

Reproductive function adjusts in response to environmental conditions in order to optimize success. In humans, this plasticity includes age of pubertal onset, hormone levels and age at menopause. These reproductive characteristics vary across populations with distinct lifestyles and following specific childhood events, and point to a role for the early-life environment in shaping adult reproductive trajectories. Epigenetic mechanisms respond to external signals, exert long-term effects on gene expression and have been shown in animal and cellular studies to regulate normal reproductive function, strongly implicating their role in these adaptations. Moreover, human cohort data have revealed differential DNA methylation signatures in proxy tissues that are associated with reproductive phenotypic variation, although the cause-effect relationships are difficult to discern, calling for additional complementary approaches to establish functionality. In this Review, we summarize how adult reproductive function can be shaped by childhood events. We discuss why the influence of the childhood environment on adult reproductive function is an important consideration in understanding how reproduction is regulated and necessitates consideration by clinicians treating women with diverse life histories. The resolution of the molecular mechanisms responsible for human reproductive plasticity could also lead to new approaches for intervention by targeting these epigenetic modifications.

Consequences of steroid-5α-reductase deficiency and inhibition in vertebrates

In 1974, a lack of 5α-dihydrotestosterone (5α-DHT), the most potent androgen across species except for fish, was shown to be the origin of a type of pseudohermaphrodism in which boys have female-like external genitalia. This human intersex condition is linked to a mutation in the steroid-5α-reductase type 2 (SRD5α2) gene, which usually produces an important enzyme capable of reducing the Δ⁴-ene of steroid C-19 and C-21 into a 5α-stereoisomer. Seeing the potential of SRD5α2 as a target for androgen synthesis, pharmaceutical companies developed 5α-reductase inhibitors (5ARIs), such as finasteride (FIN) and dutasteride (DUT) to target SRD5α2 in benign prostatic hyperplasia and androgenic alopecia. In addition to human treatment, the development of 5ARIs also enabled further research of SRD5α functions. Therefore, this review details the morphological, physiological, and molecular effects of the lack of SRD5α activity induced by both SRD5α mutations and inhibitor exposures across species. More specifically, data highlights 1) the role of 5α-DHT in the development of male secondary sexual organs in vertebrates and sex determination in non-mammalian vertebrates, 2) the role of SRD5α1 in the synthesis of the neurosteroid allopregnanolone (ALLO) and 5α-androstane-3α,17β-diol (3α-diol), which are involved in anxiety and sexual behavior, respectively, and 3) the role of SRD5α3 in N-glycosylation. This review also features the lesser known functions of SRD5αs in steroid degradation in the uterus during pregnancy and glucocorticoid clearance in the liver. Additionally, the review describes the regulation of SRD5αs by the receptors of androgens, progesterone, estrogen, and thyroid hormones, as well as their differential DNA methylation. Factors known to be involved in their differential methylation are age, inflammation, and mental stimulation. Overall, this review helps shed light on the various essential functions of SRD5αs across species.

Role of Hepatic Glucocorticoid Receptor in Metabolism in Models of 5αR1 Deficiency in Male Mice

Inhibition of 5α-reductases impairs androgen and glucocorticoid metabolism and induces insulin resistance in humans and rodents. The contribution of hepatic glucocorticoids to these adverse metabolic changes was assessed using a liver-selective glucocorticoid receptor (GR) antagonist, A-348441. Mice lacking 5α-reductase 1 (5αR1-KO) and their littermate controls were studied during consumption of a high-fat diet, with or without A-348441(120 mg/kg/d). Male C57BL/6 mice (age, 12 weeks) receiving dutasteride (1.8 mg/kg/d)) or vehicle with consumption of a high-fat diet, with or without A-348441, were also studied. In the 5αR1-KO mice, hepatic GR antagonism improved diet-induced insulin resistance but not more than that of the controls. Liver steatosis was not affected by hepatic GR antagonism in either 5αR1KO mice or littermate controls. In a second model of 5α-reductase inhibition using dutasteride and hepatic GR antagonism with A-348441 attenuated the excess weight gain resulting from dutasteride (mean ± SEM, 7.03 ± 0.5 vs 2.13 ± 0.4 g; dutasteride vs dutasteride plus A-348441; P < 0.05) and normalized the associated hyperinsulinemia after glucose challenge (area under the curve, 235.9 ± 17 vs 329.3 ± 16 vs 198.4 ± 25 ng/mL/min; high fat vs high fat plus dutasteride vs high fat plus dutasteride plus A-348441, respectively; P < 0.05). However, A-348441 again did not reverse dutasteride-induced liver steatosis. Thus, overall hepatic GR antagonism improved the insulin resistance but not the steatosis induced by a high-fat diet. Moreover, it attenuated the excessive insulin resistance caused by pharmacological inhibition of 5α-reductases but not genetic disruption of 5αR1. The use of dutasteride might increase the risk of type 2 diabetes mellitus and reduced exposure to glucocorticoids might be beneficial.

Factors impacting on the action of glucocorticoids in patients receiving glucocorticoid therapy

Glucocorticoids (GCs) are steroid hormones, which are essential for life. They are secreted by the adrenal cortex under the control of the hypothalamic-pituitary-adrenal (HPA) axis. Glucocorticoids are essential for the normal function of most organ systems and, in both, excess and deficiency can lead to significant adverse consequences. Adrenal insufficiency (AI) is a rare, life-threatening disorder characterized by insufficient production of corticosteroid hormones. Primary AI is defined by the inability of the adrenal cortex to produce sufficient amounts of glucocorticoids and/or mineralocorticoids despite normal or increased adrenocorticotropin hormone (ACTH). Secondary AI is adrenal hypofunction due to insufficient amount of ACTH produced by the pituitary gland. Conventional treatment of both primary and secondary adrenal insufficiencies involves lifelong glucocorticoid replacement therapy. The role of cortisol deficiency and the impact of hydrocortisone replacement on morbidity and mortality in this patient group are under increasing scrutiny. Established glucocorticoid replacement regimens do not completely mirror endogenous hormonal production, and their monitoring to ensure optimum therapy is hampered by the lack of reliable biomarkers of hormone sufficiency. A further confounding issue is the tissue-specific regulation of glucocorticoid through the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) with research focusing on the role of this prereceptor regulation in the development of adverse metabolic features in patients. This review defines the factors influencing glucocorticoid action in patients with adrenal insufficiency receiving glucocorticoid therapy.

Dysregulation of Cortisol Metabolism in Equine Pituitary Pars Intermedia Dysfunction

Equine Cushing disease [pituitary pars intermedia dysfunction (PPID)] is a common condition of older horses, but its pathophysiology is complex and poorly understood. In contrast to pituitary-dependent hyperadrenocorticism in other species, PPID is characterized by elevated plasma ACTH but not elevated plasma cortisol. In this study, we address this paradox and the hypothesis that PPID is a syndrome of ACTH excess in which there is dysregulation of peripheral glucocorticoid metabolism and binding. In 14 horses with PPID compared with 15 healthy controls, we show that in plasma, cortisol levels and cortisol binding to corticosteroid binding globulin were not different; in urine, glucocorticoid and androgen metabolites were increased up to fourfold; in liver, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) expression was reduced; in perirenal adipose tissue, 11β-HSD1 and carbonyl reductase 1 expression was increased; and tissue cortisol levels were not measurably different. The combination of normal plasma cortisol with markedly enhanced urinary cortisol metabolite excretion and dysregulated tissue-specific steroid-metabolizing enzymes suggests that cortisol clearance is increased in horses with PPID. We infer that the ACTH excess may be compensatory and pituitary pathology and autonomous secretion may be a secondary rather than primary pathology. It is possible that successful therapy in PPID may be targeted either at lowering ACTH or, paradoxically, at reducing cortisol clearance.

Hypothalamus-Pituitary-Adrenal Dysfunction in Cholestatic Liver Disease

The Hypothalamic-Pituitary-Adrenal (HPA) axis has an important role in maintaining the physiological homeostasis in relation to external and internal stimuli. The HPA axis dysfunctions were extensively studied in neuroendocrine disorders such as depression and chronic fatigue syndrome but less so in hepatic cholestasis, cirrhosis or other liver diseases. The HPA axis controls many functions of the liver through neuroendocrine forward signaling pathways as well as negative feedback mechanisms, in health and disease. This review describes cell and molecular mechanisms of liver and HPA axis physiology and pathology. Evidence is presented from clinical and experimental model studies, demonstrating that dysfunctions of HPA axis are correlated with liver cholestatic disorders. The functional interactions of HPA axis with the liver and immune system in cases of bacterial and viral infections are also discussed. Proinflammatory cytokines stimulate glucocorticoid (GC) release by adrenals but they also inhibit bile acid (BA) efflux from liver. Chronic hepatic inflammation leads to cholestasis and impaired GC metabolism in the liver, so that HPA axis becomes depressed. Recently discovered interactions of GC with self-oscillating transcription factors that generate circadian rhythms of gene expression in brain and liver, in the context of GC replacement therapies, are also outlined.

Hyperactivity of Hypothalamic-Pituitary-Adrenal Axis Due to Dysfunction of the Hypothalamic Glucocorticoid Receptor in Sigma-1 Receptor Knockout Mice

Sigma-1 receptor knockout (σ₁R-KO) mice exhibit a depressive-like phenotype. Because σ₁R is highly expressed in the neuronal cells of hypothalamic paraventricular nuclei (PVN), this study investigated the influence of σ₁R deficiency on the regulation of the hypothalamic-pituitary-adrenocortical (HPA) axis. Here, we show that the levels of basal serum corticosterone (CORT), adrenocorticotropic hormone (ACTH) and corticotrophin releasing factor (CRF) as well as the level of CRF mRNA in PVN did not significantly differ between adult male σ₁R-KO mice and wild-type (WT) mice. Acute mild restraint stress (AMRS) induced a higher and more sustainable increase in activity of HPA axis and CRF expression in σ₁R-KO mice. Percentage of dexamethasone (Dex)-induced reduction in level of CORT was markedly attenuated in σ₁R^-/- mice. The levels of glucocorticoid receptor (GR) and protein kinase C (PKC) phosphorylation were reduced in the PVN of σ₁R-KO mice and σ₁R antagonist NE100-treated WT mice. The exposure to AMRS in σ₁R-KO mice induced a stronger phosphorylation of cAMP-response element binding protein (CREB) in PVN than that in WT mice. Intracerebroventricular (i.c.v.) injection of PKC activator PMA for 3 days in σ₁R-KO mice not only recovered the GR phosphorylation and the percentage of Dex-reduced CORT but also corrected the AMRS-induced hyperactivity of HPA axis and enhancement of CRF mRNA and CREB phosphorylation. Furthermore, the injection (i.c.v.) of PMA in σ₁R-KO mice corrected the prolongation of immobility time in forced swim test (FST) and tail suspension test (TST). These results indicate that σ₁R deficiency causes down-regulation of GR by reducing PKC phosphorylation, which attenuates GR-mediated feedback inhibition of HPA axis and facilitates the stress response of HPA axis leading to the production of depressive-like behaviors.

Metabolic dysfunction in female mice with disruption of 5α-reductase 1

5α-Reductases irreversibly catalyse A-ring reduction of pregnene steroids, including glucocorticoids and androgens. Genetic disruption of 5α-reductase 1 in male mice impairs glucocorticoid clearance and predisposes to glucose intolerance and hepatic steatosis upon metabolic challenge. However, it is unclear whether this is driven by changes in androgen and/or glucocorticoid action. Female mice with transgenic disruption of 5α-reductase 1 (5αR1-KO) were studied, representing a 'low androgen' state. Glucocorticoid clearance and stress responses were studied in mice aged 6 months. Metabolism was assessed in mice on normal chow (aged 6 and 12 m) and also in a separate cohort following 1-month high-fat diet (aged 3 m). Female 5αR1-KO mice had adrenal suppression (44% lower AUC corticosterone after stress), and upon corticosterone infusion, accumulated hepatic glucocorticoids (~27% increased corticosterone). Female 5αR1-KO mice aged 6 m fed normal chow demonstrated insulin resistance (~35% increased area under curve (AUC) for insulin upon glucose tolerance testing) and hepatic steatosis (~33% increased hepatic triglycerides) compared with controls. This progressed to obesity (~12% increased body weight) and sustained insulin resistance (~38% increased AUC insulin) by age 12 m. Hepatic transcript profiles supported impaired lipid β-oxidation and increased triglyceride storage. Female 5αR1-KO mice were also predisposed to develop high-fat diet-induced insulin resistance. Exaggerated predisposition to metabolic disorders in female mice, compared with that seen in male mice, after disruption of 5αR1 suggests phenotypic changes may be underpinned by altered metabolism of glucocorticoids rather than androgens.

The modulation of corticosteroid metabolism by hydrocortisone therapy in patients with hypopituitarism increases tissue glucocorticoid exposure

CONTEXT

Patients with hypopituitarism have increased morbidity and mortality. There is ongoing debate about the optimum glucocorticoid (GC) replacement therapy.

OBJECTIVE

To assess the effect of GC replacement in hypopituitarism on corticosteroid metabolism and its impact on body composition.

DESIGN AND PATIENTS

We assessed the urinary corticosteroid metabolite profile (using gas chromatography/mass spectrometry) and body composition (clinical parameters and full body DXA) of 53 patients (19 female, median age 46 years) with hypopituitarism (33 ACTH-deficient/20 ACTH-replete) (study A). The corticosteroid metabolite profile of ten patients with ACTH deficiency was then assessed prospectively in a cross over study using three hydrocortisone (HC) dosing regimens (20/10 mg, 10/10 mg and 10/5 mg) (study B) each for 6 weeks. 11 beta-hydroxysteroid dehydrogenase 1 (11β-HSD1) activity was assessed by urinary THF+5α-THF/THE.

SETTING

Endocrine Centres within University Teaching Hospitals in the UK and Ireland.

MAIN OUTCOME MEASURES

Urinary corticosteroid metabolite profile and body composition assessment.

RESULTS

In study A, when patients were divided into three groups - patients not receiving HC and patients receiving HC≤20 mg/day or HC>20 mg/day - patients in the group receiving the highest daily dose of HC had significantly higher waist-to-hip ratio (WHR) than the ACTH replete group. They also had significantly elevated THF+5α-THF/THE (P=0.0002) and total cortisol metabolites (P=0.015). In study B, patients on the highest HC dose had significantly elevated total cortisol metabolites and all patients on HC had elevated THF+5α-THF/THE ratios when compared to controls.

CONCLUSIONS

In ACTH-deficient patients daily HC doses of >20 mg/day have increased WHR, THF+5α-THF/THE ratios and total cortisol metabolites. GC metabolism and induction of 11β-HSD1 may play a pivitol role in the development of the metabolically adverse hypopituitary phenotype.

Adverse effects of 5α-reductase inhibitors: What do we know, don't know, and need to know?

Steroids are important physiological orchestrators of endocrine as well as peripheral and central nervous system functions. One of the key processes for regulation of these molecules lies in their enzymatic processing by a family of 5α-reductase (5α-Rs) isozymes. By catalyzing a key rate-limiting step in steroidogenesis, this family of enzymes exerts a crucial role not only in the physiological control but also in pathological events. Indeed, both 5α-R inhibition and supplementation of 5α-reduced metabolites are currently used or have been proposed as therapeutic strategies for a wide array of pathological conditions. In particular, the potent 5α-R inhibitors finasteride and dutasteride are used in the treatments of benign prostatic hyperplasia (BPH), as well as in male pattern hair loss (MPHL) known as androgenetic alopecia (AGA). Recent preclinical and clinical findings indicate that 5α-R inhibitors evoke not only beneficial, but also adverse effects. Future studies should investigate the biochemical and physiological mechanisms that underlie the persistence of the adverse sexual side effects to determine why a subset of patients is afflicted with such persistence or irreversible adverse effects. Also a better focus of clinical research is urgently needed to better define those subjects who are likely to be adversely affected by such agents. Furthermore, research on the non-sexual adverse effects such as diabetes, psychosis, depression, and cognitive function are needed to better understand the broad spectrum of the effects these drugs may elicit during their use in treatment of AGA or BPH. In this review, we will summarize the state of art on this topic, overview the key unresolved questions that have emerged on the pharmacological targeting of these enzymes and their products, and highlight the need for further studies to ascertain the severity and duration of the adverse effects of 5α-R inhibitors, as well as their biological underpinnings.

The HPA axis response to critical illness: New study results with diagnostic and therapeutic implications

For decades, elevated plasma cortisol concentrations in critically ill patients were exclusively ascribed to a stimulated hypothalamus-pituitary-adrenal axis with increased circulating adrenocorticotropic hormone (ACTH) inferred to several-fold increase adrenal cortisol synthesis. However, 'ACTH-cortisol dissociation' has been reported during critical illness, referring to low circulating ACTH coinciding with elevated circulating cortisol. It was recently shown that metabolism of cortisol is significantly reduced in critically ill patients explained by a suppression of the activity and expression of cortisol metabolizing enzymes in kidney and liver. This reduced cortisol breakdown determines hypercortisolemia, much more than increased cortisol production, in the critically ill. Although the low plasma ACTH concentrations, evoked by the elevated plasma cortisol via feedback inhibition, are part of this adaptation, they may negatively affect adrenocortical structure and function in the prolonged phase of critical illness. These new insights have implications for diagnosis and treatment of adrenal insufficiency in critically ill patients.

The role of adrenal gland microenvironment in the HPA axis function and dysfunction during sepsis

Sepsis and septic shock in response to bacterial or viral infections remain the major health problem worldwide. Despite decades of intensive research and improvements in medical care, severe sepsis is associated with high mortality. Rapid activation of the adrenal gland glucocorticoid and catecholamine production is a fundamental component of the stress response and is essential for survival of the host. However, in many critically ill patients this homeostatic function of the adrenal gland is often impaired. In these patients, plasma levels of adrenocorticotropic hormone (ACTH) and cortisol are often dissociated. This has been attributed to the stimulatory action of non-ACTH factors within the adrenal gland such as cytokines, and recently with decreased cortisol metabolism and suppressed ACTH synthesis. Regulation of the hypothalamus-pituitary-adrenal (HPA) axis function during sepsis is a complex process which involves various immune and neuroendocrine interactions occurring at the levels of the central nervous system (CNS) and the adrenal gland. A coordinated interaction of numerous cell types and systems within the adrenal gland is involved in the sustained adrenal glucocorticoid production. This review article describes and discusses recent experimental findings regarding the role of adrenal gland microenvironment including the adrenal vasculature and the immune-adrenal crosstalk in the disregulated HPA axis during sepsis conditions. In summary, in addition to the reduced cortisol breakdown and related ACTH suppression, sepsis-mediated chronic activation of the immune-adrenal crosstalk and vascular dysfunction may contribute to the HPA axis dysregulation found in septic patients.

5α-Reductase type 1 deficiency or inhibition predisposes to insulin resistance, hepatic steatosis, and liver fibrosis in rodents

5α-Reductase type 1 (5αR1) catalyses A-ring reduction of androgens and glucocorticoids in liver, potentially influencing hepatic manifestations of the metabolic syndrome. Male mice, homozygous for a disrupted 5αR1 allele (5αR1 knockout [KO] mice), were studied after metabolic (high-fat diet) and fibrotic (carbon tetrachloride [CCl4]) challenge. The effect of the 5α-reductase inhibitor finasteride on metabolism was investigated in male obese Zucker rats. While eating a high-fat diet, male 5αR1-KO mice demonstrated greater mean weight gain (21.6 ± 1.4 vs 16.2 ± 2.4 g), hyperinsulinemia (insulin area under the curve during glucose tolerance test 609 ± 103 vs. 313 ± 66 ng ⋅ mL(-1) ⋅ min), and hepatic steatosis (liver triglycerides 136.1 ± 17.0 vs. 89.3 ± 12.1 μmol ⋅ g(-1)). mRNA transcript profiles in liver were consistent with decreased fatty acid β-oxidation and increased triglyceride storage. 5αR1-KO male mice were more susceptible to fibrosis after CCl4 administration (37% increase in collagen staining). The nonselective 5α-reductase inhibitor finasteride induced hyperinsulinemia and hepatic steatosis (10.6 ± 1.2 vs. 7.0 ± 1.0 μmol ⋅ g(-1)) in obese male Zucker rats, both intact and castrated. 5αR1 deficiency induces insulin resistance and hepatic steatosis, consistent with the intrahepatic accumulation of glucocorticoids, and predisposes to hepatic fibrosis. Hepatic steatosis is independent of androgens in rats. Variations in 5αR1 activity in obesity and with nonselective 5α-reductase inhibition in men with prostate disease may have important consequences for the onset and progression of metabolic liver disease.