Mineralocorticoid Receptor Agonist Research Articles

До проблеми оптимальної антигіпертензивної терапії хворих на артеріальну гіпертензію з цукровим діабетом 2 типу (за даними Рекомендацій Європейського товариства з гіпертензії 2023 року)

The review of the problem of optimal antihypertensive therapy for patients with arterial hypertension (AH) with type 2 diabetes mellitus (T2DM) through the prism of the 2023 European Society of Hypertension Guidelines examines the issues of diagnosis, prevention and treatment of very high-risk patients. In the historical aspect, the evolution of knowledge regarding this problem is considered, data on the epidemiology of comorbid pathology are given, attention is focused on the target levels of blood pressure and approaches to its monitoring. The authors comment on important population studies with a high level of evidence in this regard, touch on the aspects of prescribing new classes of drugs, namely mineralocorticoid receptor agonists and sodium-dependent glucose cotransporter type 2 inhibitors for reducing blood pressure and glycemia, considering the classes and levels of evidence. At the end, the issue of prevention and treatment of manifestations of cardiovascular pathology in patients with type 2 diabetes is highlighted. Key words: arterial hypertension, type 2 diabetes, 2023 European Society of Hypertension Guidelines, diagnosis, prevention and treatment, cardiovascular pathology.

The Concurrent Administration of Dexamethasone and Aldosterone Effectively Mitigates the Pronounced Pro-ulcerogenic Effect of Dexamethasone on the Gastric Mucosa in Rats

We previously established that the effect of dexamethasone (Dex) on the gastric ulceration is time dependent. Administering Dex 1 hour before an ulcerogenic stimulus provides gastroprotection, but extending the interval to 24 hours transforms its effect into a pro-ulcerogenic one. The prolonged maintenance of blood glucose levels induced by Dex, accompanied by catabolic effects, may, in part, account for its pro-ulcerogenic nature (Filaretova et., Inflammopharmacology 2009). Given the evidence that Dex primarily binds to glucocorticoid receptors (GRs), we hypothesized that Dex-induced imbalance in the activation of GRs and mineralocorticoid receptors (MRs) could contribute to the pro-ulcerogenic effect of Dex. We partly confirmed this (Filaretova and Sudalina, FASEB J. 2019). To further validate this hypothesis, we conducted a study to determine whether correcting the imbalance in the activation of GRs and the MRs, induced by Dex, through co-administering Dex with the MR agonist aldosterone (Aldo), can mitigate the pro-ulcerogenic effect of Dex. The effects of separate and combined administration of Dex and Aldo at a dose of 1 mg/kg (i.p.) 1 hour and 24 hours before the onset of ulcerogenic stimulus on the gastric erosions was evaluated in rats. Gastric injury was induced by indomethacin (IM, 35 mg/kg, sc) in preliminary fasted rats. Four hours after IM administration, the rats were decapitated, the stomachs were removed to estimate the erosion area; the adrenal glands, thymus and spleen were remove to estimate their weight, and trunk blood was collected to test the corticosterone and glucose levels. We confirmed the gastroprotective effect of Dex administered 1 hour and the pronounced pro-ulcerogenic effect of Dex administered 24 hours before IM. Aldo itself, administered 1 hour before IM had no effect on the gastric erosions, however, when administered 24 hours before IM, it led to a pro-ulcerogenic effect of IM, but much less pronounced comparing with that of Dex. Co-administration Dex and Aldo 1 hour before IM resulted in the gastroprotection similar to that of Dex alone. Co-administration Dex and Aldo 24 hours before IM effectively mitigates the pronounced pro-ulcerogenic effect of dexamethasone on the gastric mucosa. Dex administration resulted in a sharp decrease in the blood corticosterone level both when administered 1 hour and 24 hours before IM, however, the corticosterone levels in 24 hours were significantly lower than in 1 hour. Aldo itself did not lead to a significant decrease the corticosterone levels neither after 1 hour nor after 24 hours. We confirmed our previous results that Dex administration both 1 hour and 24 hours before IM leads to an increase in blood glucose levels. Administration of Aldo alone did change glucose levels. The effect of the combined administration of Dex and Aldo on glucose levels did not differ from that of Dex alone. 24 hours after Dex administration alone or co-administration Dex with Aldo, pronounced catabolic effects appeared: a decrease in the relative weight of the adrenal glands, thymus and spleen. In conclusion, the concurrent administration of Dex and Aldo effectively mitigates the pronounced pro-ulcerogenic effect of Dex on the gastric mucosa in rats. The results further confirmed our hypothesis. State Program 47 SP “Scientific and Technological Development of the Russian Federation” (2019-2030), 0134-2019-0001. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

D-Pinitol mitigates post-traumatic stress disorder-like behaviors induced by single prolonged stress in mice through mineralocorticoid receptor antagonism

Post-traumatic stress disorder (PTSD) is a mental illness that can occur in individuals who have experienced trauma. Current treatments for PTSD, typically serotonin reuptake inhibitors, have limited effectiveness for patients and often cause serious adverse effects. Therefore, a novel class of treatment with better pharmacological profile is necessary. D-Pinitol has been reported to be effective for depression and anxiety disorders, but there are no reports associated with PTSD. In the present study, we investigated the effects of D-pinitol in a mouse model of PTSD induced by a single prolonged stress (SPS) protocol. We examined the therapeutic effects of D-pinitol on emotional and cognitive impairments in the SPS mouse model. We also investigated the effects of D-pinitol on fear memory formation. Mineralocorticoid receptor transactivation assay, Western blot, and quantitative PCR were employed to investigate how D-pinitol exerts its pharmacological activities. D-Pinitol ameliorated PTSD-like behaviors in a SPS mouse model. D-Pinitol also normalized the increased mRNA expression levels and protein levels of the mineralocorticoid receptor in the amygdala. A mineralocorticoid receptor agonist reversed the effects of D-pinitol on fear extinction and recall, and the antagonistic property of D-pinitol against the mineralocorticoid receptor was confirmed in vitro. Our findings suggest that D-pinitol could serve as a potential therapeutic agent for PTSD due to its antagonistic effect on the mineralocorticoid receptor.

A Selective Mineralocorticoid Receptor Blocker, Esaxerenone, Attenuates Vascular Dysfunction in Diabetic C57BL/6 Mice.

Pharmacological blockade of mineralocorticoid receptors (MRs) is a potential therapeutic approach to reduce cardiovascular complications since MRs play a crucial role in cardiovascular regulation. Recent studies suggest that MR antagonists affect several extrarenal tissues, including vessel function. We investigated the effect of a novel nonsteroidal selective MR blocker, esaxerenone, on diabetes-induced vascular dysfunction. Diabetes was induced by a single dose of streptozotocin in 8-week-old male C57BL/6 mice. Esaxerenone (3 mg/kg/day) or a vehicle was administered by gavage to diabetic mice for 3 weeks. Metabolic parameters, plasma aldosterone levels, and parameters related to renal function were measured. Endothelium-dependent or -independent vascular responses of the aortic segments were analyzed with acetylcholine or sodium nitroprusside, respectively. Human umbilical vein endothelial cells (HUVECs) were used for the in vitro study. Induction of diabetes elevated plasma aldosterone level (P＜0.05) and impaired endothelium-dependent vascular relaxation (P＜0.05). The administration of esaxerenone ameliorated the endothelial dysfunction (P＜0.01) without the alteration of metabolic parameters, blood pressure, and renal function. Esaxerenone improved the eNOSSer1177 phosphorylation in the aorta obtained from diabetic mice (P＜0.05) compared with that in the vehicle-treated group. Furthermore, a major MR agonist, aldosterone, decreased eNOSSer1177 phosphorylation and increased eNOSThr495 phosphorylation in HUVECs, which recovered with esaxerenone. Esaxerenone ameliorated the endothelium-dependent vascular relaxation caused by aldosterone in the aortic segments obtained from C57BL/6 mice (P＜0.001). Esaxerenone attenuates the development of diabetes-induced endothelial dysfunction in mice. These results suggest that esaxerenone has potential vascular protective effects in individuals with diabetes.

Diabetic kidney disease treatment: new perspectives.

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease and end-stage kidney disease worldwide, as the obesity epidemic and the burden of diabetes continue to rise globally. In general, guideline management of patients with DKD recommends lifestyle modifications, blood pressure and glycemic control, and dyslipidemia treatment along with other cardiovascular disease risk reduction measures. The inhibition of the renin-angiotensin system (RAS) using an angiotensin-converting enzyme inhibitor or an angiotensin II receptor blocker remains the foundational therapy for DKD. In type 2 diabetes (T2D), significant advances in therapeutics, including the sodium-glucose cotransporter-2 inhibitors (SGLT2i), the glucagon-like peptide-1 receptor agonists (GLP-1 RA), and the nonsteroidal mineralocorticoid receptor agonist (MRA) finerenone, have dramatically expanded the armamentarium for treating DKD and its cardiovascular complications. Initiating, optimizing, and sustaining evidence-based pharmacological therapy using a therapeutic combination of RAS inhibitor + SGLT2i/GLP-1 RA + nonsteroidal MRA + statin is likely to significantly improve outcomes for T2D with DKD. Research into potential novel therapeutic targets for DKD remains particularly active and brings much anticipation and optimism to this field.

Mineralocorticoid receptor agonist aldosterone rescues hippocampal neural stem cell proliferation defects and improves postoperative cognitive function in aged mice

Objectives Hippocampal neurogenesis is closely related to learning and memory, and hippocampal neurogenesis disorders are involved in the development of many neurodegenerative diseases. Mineralocorticoid receptor (MR) plays a vital role in regulating stress response, neuroendocrine and cognitive functions, and is involved in regulating the integrity and stability of neural networks. However, the potential role of MR in the pathogenesis of postoperative cognitive dysfunction (POCD) is unclear. Therefore, this study evaluated the effect and mechanism of MR activation on postoperative hippocampal neurogenesis and cognitive function in aged mice. Methods 18-month-old male Kunming mice were randomly divided into Control group (C group), Surgery group (S group), Surgery+ Aldosterone group (S+Aldo group), Surgery + Wortmannin group (S+Wort group), Surgery + Aldosterone + Wortmannin group (S+Aldo+Wort group). Laparotomy was used to establish an animal model of postoperative cognitive dysfunction. After surgery, mice were intraperitoneally injected with aldosterone (100 ug/kg,150 ug/kg,200 ug/kg) and / or wortmannin (1 mg/kg); One day before the sacrifice, mice were injected intraperitoneally with BrdU (100 mg / kg / time, 3 times in total). Mice were subjected to Morris water maze and field tests at 1, 3, 7, and 14 days after surgery. Immunofluorescence was used to detect the number of BrdU +, Nestin +, BrdU/Nestin + positive cells in the hippocampal dentate gyrus of mice at 1, 3, 7 and 14 days after surgery. Western-blot was used to detect PI3K/Akt/GSK-3β signaling pathway related proteins Akt, p-Akt, GSK-3β, P-GSK-3β expression. Results Stress impairs the performance of aged mice in water maze and open field tests, reduces the number of BrdU/Nestin+ cells in the hippocampal dentate gyrus, and inhibits the phosphorylation of Akt and GSK-3β proteins in the hippocampus. Aldosterone treatment promotes P-Akt, P-GSK-3β protein expression and hippocampal neural stem cell proliferation, and improves postoperative cognitive dysfunction. However, wortmannin treatment significantly reversed these effects of aldosterone. Conclusions The mineralocorticoid receptor agonist aldosterone promotes the proliferation of hippocampal neural stem cells and improves cognitive dysfunction in aged mice after surgery, and the mechanism may be related to activation of PI3K/Akt/GSK-3β signaling.

Myeloid mineralocorticoid receptors contribute to skeletal muscle repair in muscular dystrophy and acute muscle injury.

Suppressing mineralocorticoid receptor (MR) activity with MR antagonists is therapeutic for chronic skeletal muscle pathology in Duchenne muscular dystrophy (DMD) mouse models. Although mechanisms underlying clinical MR antagonist efficacy for DMD cardiomyopathy and other cardiac diseases are defined, mechanisms in skeletal muscles are not fully elucidated. Myofiber MR knockout improves skeletal muscle force and a subset of dystrophic pathology. However, MR signaling in myeloid cells is known to be a major contributor to cardiac efficacy. To define contributions of myeloid MR in skeletal muscle function and disease, we performed parallel assessments of muscle pathology, cytokine levels, and myeloid cell populations resulting from myeloid MR genetic knockout in muscular dystrophy and acute muscle injury. Myeloid MR knockout led to lower levels of C-C motif chemokine receptor 2 (CCR2)-expressing macrophages, resulting in sustained myofiber damage after acute injury of normal muscle. In acute injury, myeloid MR knockout also led to increased local muscle levels of the enzyme that produces the endogenous MR agonist aldosterone, further supporting important contributions of MR signaling in normal muscle repair. In muscular dystrophy, myeloid MR knockout altered cytokine levels differentially between quadriceps and diaphragm muscles, which contain different myeloid populations. Myeloid MR knockout led to higher levels of fibrosis in dystrophic diaphragm. These results support important contributions of myeloid MR signaling to skeletal muscle repair in acute and chronic injuries and highlight the useful information gained from cell-specific genetic knockouts to delineate mechanisms of pharmacological efficacy.

Značaj titracije doze beta blokatora u srčanoj insuficijenciji

Heart failure is a clinical syndrome, characterized by the inability of the heart to pump an adequate amount of blood according to the needs of the organs and tissues, at rest and during exertion, despite normal blood flow to the heart. Treatment includes hygienic and dietary measures, pharmacological treatment, installation of an appropriate device, surgical treatment and heart transplantation. Indispensable groups of drugs that reduce mortality in the treatment of this disease are beta-blockers, angiotensin-converting enzyme inhibitors (ACE inhibitors)/angiotensin receptor neprilysin inhibitors (ARNI), mineralocorticoid receptor agonists (MRA), sodium-glucose cotransporter type 2 inhibitors (SGLT inhibitors). By blocking beta receptors and sympathies, beta-blockers relieve the cell, which tried to compensate for the weak function by "accumulating" them. Their gradual introduction is necessary in order to achieve the appropriate effect. Therapy with beta-blockers is started with the lowest dose, which, depending on the clinical condition of the patient, is increased every two weeks until the full dose is reached. The rule of thumb is that a smaller dose is better than none. Thanks to the high selectivity of beta-blockers, they can be used in patients who have comorbidities and heart failure, which is unfortunately a very common case. They can be administered to the patients with chronic obstructive pulmonary disease, diabetes mellitus, peripheral occlusive disease and similar. Beta-blockers, in addition to angiotensinconverting enzyme inhibitors/angiotensin receptor neprilysin inhibitors, mineralocorticoid receptor agonists and sodium-glucose cotransporter type 2 inhibitors, represent the most significant group of drugs that have the greatest impact on disease prognosis, quality of life, morbidity and mortality in patients with heart failure with reduced ejection fraction. Today, they are not used enough because of the fear of developing hypotension and bradycardia, and they are often mistakenly considered contraindicated in the presence of numerous comorbidities.

Anti-inflammatory and neuroprotective properties of the corticosteroid fludrocortisone in retinal degeneration

The pathogenesis of outer retinal degenerations has been linked to the elevation of cytokines that orchestrate pro-inflammatory responses within the retinal milieu, and which are thought to play a role in diseases such as geographic atrophy (GA), an advanced form of AMD. Here we sought investigate the anti-inflammatory and mechanistic properties of fludrocortisone (FA), as well as triamcinolone acetonide (TA), on Müller cell-mediated cytokine expression in response to inflammatory challenge. In addition, we investigated the neuroprotective efficacy of FA and TA in a photo-oxidative damage (PD), a model of outer retinal degeneration. Expression of CCL2, IL-6, and IL-8 with respect to FA and TA were assessed in Müller cells in vitro, following simulation with IL-1β or TNF-α. The dependency of this effect on mineralocorticoid and glucocorticoid signaling was also interrogated for both TA and TA via co-incubation with steroid receptor antagonists. For the PD model, C57BL/6 mice were intravitreally injected with FA or TA, and changes in retinal pathology were assessed via electroretinogram (ERG) and optical coherence tomography (OCT). FA and TA were found to dramatically reduce the expression of CCL2, IL-6, and IL-8 in Müller glia in vitro after inflammatory challenge with IL-1β or TNF-α (P < 0.05). Though FA acts as both a mineralocorticoid and glucocorticoid receptor agonist, co-incubation with selective steroid antagonists revealed that the suppressive effect of FA on CCL2, IL-6, and IL-8 expression is mediated by glucocorticoid signaling (P < 0.05). In PD, intravitreal FA was found to ameliorate outer-retinal atrophy as measured by ERG and OCT (P < 0.05), while TA had no significant effect (P > 0.05). Our data indicate potent anti-inflammatory and mechanistic properties of corticosteroids, specifically FA, in suppressing inflammation and neurodegeneration degeneration associated with outer retinal atrophy. Taken together, our findings indicate that corticosteroids such as FA may have value as a potential therapeutic for outer retinal degenerations where such pro-inflammatory factors are implicated, including AMD.

Drospirenone Effects on the Plasminogen Activator System in Immortalized Human Endometrial Endothelial Cells.

Drospirenone (DRSP) is a fourth-generation progestin that interacts with the progesterone receptor (PR) and androgen receptor (AR) in addition to uniquely interacting to the mineralocorticoid receptor (MR). The known effects of DRSP via the mineralocorticoid receptor (MR) are limited. This study seeks to determine if DRSP alters plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (tPA) in human immortalized endometrial endothelial cells (HEEC) and if such changes in the plasminogen activator system (PAS) are mediated through the MR or AR. The in vitro cell culture experiments utilizing an immortalized human endometrial endothelial cell line evaluated two concentrations of DRSP on PAI-1 and tPA levels in the culture media using specific enzyme-linked immunoassays (ELISA). Experiments adding DRSP with an androgen receptor blocker, flutamide, or a mineralocorticoid receptor agonist, aldosterone, were performed to elucidate which receptor(s) mediated the PAS effects. DRSP 10μM significantly decreased both HEEC levels of PAI-1 and tPA to 0.75 ± 0.04 and 0.82 ± 0.05 of control, respectively. These direct effects were blunted by flutamide, an AR antagonist. PAI-1 and tPA were not changed by the MR agonist, aldosterone. DRSP significantly decreased both PAI-1 and tPA in the HEECs via the androgen receptor.

Apararenone in patients with diabetic nephropathy: results of a randomized, double-blind, placebo-controlled phase 2 dose\u2013response study and open-label extension study

BackgroundWe investigated the efficacy and safety of apararenone (MT-3995), a non-steroidal compound with mineralocorticoid receptor agonist activity, in patients with stage 2 diabetic nephropathy (DN).MethodsThe study had two parts: a dose–response, parallel-group, randomized, double-blind, placebo-controlled, multicenter, phase 2, 24-week study and an open-label, uncontrolled, 28-week extension study. Primary and secondary endpoints were the 24-week percent change from baseline in urine albumin to creatine ratio (UACR) and 24- and 52-week UACR remission rates. Safety parameters were changes from baseline in estimated glomerular filtration rate (eGFR) and serum potassium at 24 and 52 weeks, and incidences of adverse events (AEs) and adverse drug reactions (ADRs).ResultsIn the dose–response period, 73 patients received placebo and 73, 74, and 73 received apararenone 2.5 mg, 5 mg, and 10 mg, respectively. As a percentage of baseline, mean UACR decreased to 62.9%, 50.8%, and 46.5% in the 2.5 mg, 5 mg, and 10 mg apararenone groups, respectively, at week 24 (placebo: 113.7% at week 24; all P < 0.001 vs placebo). UACR remission rates at week 24 were 0.0%, 7.8%, 29.0%, and 28.1% in the placebo and apararenone 2.5 mg, 5 mg, and 10 mg groups, respectively. eGFR tended to decrease and serum potassium tended to increase, but these events were not clinically significant. AE incidence increased with dose while ADR incidence did not.ConclusionThe UACR-lowering effect of apararenone administered once daily for 24 weeks in patients with stage 2 DN was confirmed, and the 52-week administration was safe and tolerable.Clinical trial registrationNCT02517320 (dose–response study) and NCT02676401 (extension study)

Attenuation of Mineralocorticoid Receptor Signaling Promotes Vascular Recovery from Hind Limb Ischemia in a Sex Specific Manner

Peripheral arterial disease (PAD) is a growing concern affecting 8.5 million Americans annually and contributing to both fatal and non‐fatal cardiovascular ischemic events. Importantly, available evidence indicates that women experience higher rates of occlusion, reintervention, and mortality than males, however, mechanisms underlying these sex differences remain unclear. Recent evidence has revealed sex‐specific deleterious effects of mineralocorticoid receptor (MR) signaling in a variety of cardiovascular conditions including vascular inflammation and endothelial dysfunction, which have been implicated in PAD. Whether MR signaling differentially impairs microvascular adaptations in males and females following an ischemic insult, however, has not been examined. Accordingly, we evaluated the hypothesis that attenuation of MR signaling promotes microvascular compensation and perfusion recovery following hind limb ischemia (HLI) to a greater extent in females than in males involving enhanced capillary neovascularization and augmented outward remodeling of existing collaterals. Male and female C57BL/6J mice (10–12 weeks old) underwent unilateral femoral artery ligation and excision to induce HLI after implantation of pellets containing either placebo or the MR antagonist spironolactone (20mg/kg/day, sc). The contralateral leg underwent sham surgery with no ligation or excision. Hind limb perfusion was serially assessed for 28 days with laser Doppler imaging. At 28 days post occlusion, the hind limb vasculature was perfusion fixed following maximal dilation and perfused with bismuth for assessment of collateral morphology by micro‐CT imaging. These studies were complemented with immunohistochemistry and angiogenic assay experiments. Additional preliminary HLI experiments were conducted in male mice with endothelial cell‐specific MR (EC MR) deletion. Systemic inhibition of MR signaling enhanced recovery of hind limb perfusion in female, not male, mice. This effect of MR blockade was associated with greater outward collateral remodeling in females compared to males. Interestingly, spironolactone similarly increased skeletal muscle capillary density in both hind limbs of males and females consistent with impairment of VEGF‐stimulated capillary sprouting by the MR agonist aldosterone in an aortic angiogenesis assay. Finally, preliminary studies revealed enhanced recovery of hind limb perfusion in male mice with EC MR deletion and that EC MR deletion enhanced aortic capillary sprouting in vitro. Taken together, these data suggest that MR signaling limits the microvascular response to ischemia and that enhanced perfusion recovery following MR blockade in females involves greater collateral expansion compared to males. Significant vascular cell‐specificity of MR signaling underlying these responses may contribute to these sex differences and warrant further investigation.Support or Funding InformationFunded by HL136386, HL095590, and HL088105.

The expanding class of mineralocorticoid receptor modulators: New ligands for kidney, cardiac, vascular, systemic and behavioral selective actions.

This paper reviews the class of mineralocorticoid receptor (MR) modulators, especially new nonsteroidal antagonists. MR is a nuclear receptor expressed in many tissues and cell types. Aldosterone, the most important mineralocorticoid hormone and MR agonist, has many unfavorable effects, especially on the heart, blood vessels, and kidneys, by promoting fibrosis and tissue remodelling. Classical synthetic MR antagonists (spironolactone, eplerenone) have proven useful in clinical practice through their antihypertensive effects in resistant forms, and through benefits on morbidity and mortality in heart failure with reduced ejection fraction. These benefits are associated with important side effects, hyperkalemia being the main limitation. In the latest years, a new generation of MR modulators with a nonsteroidal structure has emerged. These compounds are more selective than classical MR antagonists, with much higher affinity for the MR than for the glucocorticoid, androgen, or progesterone receptors. Recent clinical and experimental observations suggest that nonsteroidal MR antagonists, especially finerenone, have proven superior renoprotective properties, antiproteinuric efficacy, inhibition of inflammation and heart fibrosis in animal models, without sharing the side effects of steroidal MR antagonists. Nonsteroidal MR modulators represent an interesting new therapeutic approach for the prevention and progression of chronic kidney disease and for patients with heart failure and renal disease. Despite these promising data, there are still many issues to be clarified and it is necessary to accumulate solid evidence from studies on larger numbers of patients and from head-to-head clinical trials.

Interaction between accumulated 21-deoxysteroids and mineralocorticoid signaling in 21-hydroxylase deficiency.

21-Hydroxylase deficiency (21OHD) is a rare genetic disorder in which salt-wasting syndrome occurs in 75% of cases, due to inability to synthesize cortisol and aldosterone. Recent mass spectrometry progress allowed identification of 21-deoxysteroids, i.e., 17-hydroxyprogesterone (17OHP), 21-deoxycortisol (21DF), and 21-deoxycorticosterone (21DB). We hypothesized that they may interfere with mineralocorticoid signaling and fludrocortisone therapy in patients with congenital adrenal hyperplasia (CAH) without effective glucocorticoid replacement and ACTH suppression. Our goal was to quantify circulating 21-deoxysteroids in a pediatric cohort with CAH related to 21OHD and to examine their impact on mineralocorticoid receptor (MR) activation. Twenty-nine patients with salt-wasting phenotype were classified in two groups according to their therapeutic control. During routine follow-up, 17OHP, 21DF, 21DB, and cortisol levels were quantified by liquid chromatography with tandem mass spectrometry before hydrocortisone intake and 1 and 2.5 h following treatment administration. Luciferase reporter gene assays were performed on transfected HEK293T cells while in silico modeling examined structural interactions between these steroids within ligand-binding domain of MR. Plasma 17OHP, 21DF, and 21DB accumulate in uncontrolled patients reaching micromolar concentrations even after hydrocortisone intake. 21DF and 21DB act as partial MR agonists with antagonist features similar to 17OHP, consistent with altered anchoring to Asn770 and unfavorable contact with Ala773 in ligand-binding pocket of MR. Our results demonstrate a complex interaction between all accumulating 21-deoxysteroids in uncontrolled 21OHD patients and mineralocorticoid signaling and suggest that appropriate steroid profiling should optimize management and follow-up of such patients, as keeping those steroids to low plasma levels should attest therapeutic efficacy and prevent interference with MR signaling.

The Possible Mechanism of the Appearance of Nightmares in Post-Traumatic Stress Disorder and Approaches to Their Prevention

Abstract—It is hypothesized that the basis of nightmares in post-traumatic stress disorder (PTSD) is modification of synaptic transmission in neural circuits that contain one of the following structures: the visual cortex, prefrontal cortex (PfC), basolateral amygdala (BLA), hippocampus, connected with them nuclei of the thalamus and basal ganglia (BG). The emergence of dreams is promoted by the induction of long-term potentiation of excitatory inputs to the striatonigral cells and the long-term depression of the inputs to the striatopallidal cells that are connected with the visual cortex, and give rise, respectively, to a direct and indirect path way through the BG. This leads to synergistic disinhibition of certain groups of neurons in the thalamus by the output BG nuclei and the formation of activity patterns that reflect dream content in the areas of the visual cortex and hippocampus, which are connected with thalamus. The occurrence of emotionally negative episodes in dreams is a consequence of an increase in BLA activity during PTSD, whose signals are summed with the signals from the hippocampus and PfC on the neurons of the ventral striatum. This mechanism suggests that, in order to prevent nightmares, it is necessary to induce long-term depression of the excitatory inputs to the neurons of the limbic structures and to the striatonigral cells. It is undesirable to act on the receptors on the striatopallidal cells because it may simultaneously induce long-term potentiation of the excitatory inputs to the neurons of PfC, BLA, and hippocampus, which have receptors of the same types. Given the data on the types of receptors on striatal neurons, it follows from the modulation rules we earlier formulated that nightmares may be prevented by antagonists of dopamine D1 receptor and alpha1 adrenoceptor and agonists of glucocorticoid, serotonin 5-HT1B, and cannabinoid CB1 receptors. The use of mineralocorticoid and serotonin 5-HT2A receptor agonists, as well as antagonists of alpha2 adrenoreceptors and dopamine D2 receptors (which are part of some antidepressants and antipsychotics) is undesirable in order to avoid side effects. The treatment should be short-term and used only at bedtime, to avoid impairments of physical activity and sensory perception in the awake state. The consequences of the proposed mechanism are consistent with the known results of clinical studies.

Molecular evolution of the switch for progesterone and spironolactone from mineralocorticoid receptor agonist to antagonist

The mineralocorticoid receptor (MR) is highly conserved across vertebrate evolution. In terrestrial vertebrates, the MR mediates sodium homeostasis by aldosterone and also acts as a receptor for cortisol. Although the MR is present in fish, they lack aldosterone. The MR binds progesterone and spironolactone as antagonists in human MR but as agonists in zebrafish MR. We have defined the molecular basis of these divergent responses using MR chimeras between the zebrafish and human MR coupled with reciprocal site-directed mutagenesis and molecular dynamic (MD) simulation based on the crystal structures of the MR ligand-binding domain. Substitution of a leucine by threonine in helix 8 of the ligand-binding domain of the zebrafish MR confers the antagonist response. This leucine is conserved across fish species, whereas threonine (serine in rodents) is conserved in terrestrial vertebrate MR. MD identified an interaction of the leucine in helix 8 with a highly conserved leucine in helix 1 that stabilizes the agonist conformation including the interaction between helices 3 and 5, an interaction which has previously been characterized. This switch in the MR coincides with the evolution of terrestrial vertebrates and of aldosterone synthesis. It was perhaps mandatory if the appearance of aldosterone as a specific mediator of the homeostatic salt retention was to be tolerated. The conformational changes also provide insights into the structural basis of agonism versus antagonism in steroid receptors with potential implications for drug design in this important therapeutic target.

Activation of the Mineralocorticoid Receptor Leads to Increases in Protein Disulfide Isomerase Activity

Activation of the mineralocorticoid receptor (MR), a critical component of the Renin‐Angiotensin‐Aldosterone (ALDO) System (RAAS), plays an important role in inflammatory and vascular endothelial responses in addition to its well‐described effects on sodium and water homeostasis. Activation of endothelial cells and leukocytes leads to, among other factors, increased protein disulfide isomerase (PDI) release. PDI is a multifunctional oxidoreductase that catalyzes thiol/disulfide interchange reactions within the endoplasmic reticulum, is also present in circulation and at the cell surface of platelets, lymphocytes, erythrocytes and endothelial cells and plays a critical role in initiating thrombus formation. However, the interaction of ALDO, MR activation and PDI remain unclear. We hypothesized that MR activation would lead to increased PDI levels thus contributing to inflammation and oxidative stress. We first studied EA.hy926 (EA) cells, a human endothelial cell line that expresses MR. We incubated EA cells with ALDO (10 −8 M), an MR agonist, for 24 hr and observed a rise in PDI mRNA levels by qRT‐PCR (p&lt;0.01, n=5), an event that was blocked by pre‐incubation of EA cells with 1 μM canrenoic acid (CA), an MR antagonist (p&lt;0.05, n=5). Consistent with these results, measurements of PDI levels by ELISA confirmed a rise in PDI that was likewise blocked by CA (p&lt;0.01, n=4). Also, we measured PDI activity in the supernatant of ALDO‐stimulated EA cells using a Di‐E‐GSSH fluorescent marker and observed a rise in PDI activity following ALDO (10^−8 M) incubation when compared to vehicle treatment (p&lt;0.05, n=5). We then studied the effects of ALDO on HL‐60 cells, a human promyelocytic cell line that was induced to differentiate into neutrophil‐like leukocytes by incubation for 5 days with 1.3% DMSO. In these cells, we detected the presence of MR by western blot analyses and observed that ALDO (10^−8 M) stimulated a rise in PDI activity that was blocked by CA (p&lt;0.05, n=6). To test the in vivo effects of MR activation on PDI activity, we characterized a well‐described rodent model of RAAS‐mediated increased BP, inflammation and target organ damage using exogenous angiotensin II (AngII) infusion in Sprague–Dawley rats. Rats were randomized to three conditions: (1) control; (2) AngII infused (80 ng/min × 28 days); (3) AngII + eplerenone (100 mg eplerenone/kg/day × 21 days), an MR antagonist. Consistent with our in vitro data, AngII infusion led to significant increases in plasma PDI activity that was significantly reduced by approximately 65% following eplerenone treatment (p&lt;0.05, n=5/group). Thus, MR activation represents a novel mechanism for PDI regulation that may contribute to the deleterious effects of disordered RAAS activity in cardiovascular disease.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Liquiritinapioside – A mineralocorticoid-like substance from liquorice

Surface plasmon resonance (SPR) analysis of the main components of liquorice was performed and a novel strong mineralocorticoid receptor (MR) agonist, namely liquiritinapioside (LA), whose the binding constant was 1.093 × 10−5 M, was reported. As a supplement, LA has been further demonstrated to have a strong MR binding capacity through competitive binding experiments (the enrichment factor of LA was 10.22%). This study also validated the activity of LA on H9c2 cells. The expression of collagen I and the results of Masson staining were used to determine the ability of this substance to cause H9c2 cell fibrosis. Moreover, western blotting was used to verify the mechanism of compound-induced myocardial fibrosis. Overall, the attained results showed that LA could induce the activation of the TGF-β1/p38 MAPK signalling pathway through the MR to induce H9c2 cell fibrosis.

Vamorolone targets dual nuclear receptors to treat inflammation and dystrophic cardiomyopathy.

Cardiomyopathy is a leading cause of death for Duchenne muscular dystrophy. Here, we find that the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) can share common ligands but play distinct roles in dystrophic heart and skeletal muscle pathophysiology. Comparisons of their ligand structures indicate that the Δ9,11 modification of the first-in-class drug vamorolone enables it to avoid interaction with a conserved receptor residue (N770/N564), which would otherwise activate transcription factor properties of both receptors. Reporter assays show that vamorolone and eplerenone are MR antagonists, whereas prednisolone is an MR agonist. Macrophages, cardiomyocytes, and CRISPR knockout myoblasts show vamorolone is also a dissociative GR ligand that inhibits inflammation with improved safety over prednisone and GR-specific deflazacort. In mice, hyperaldosteronism activates MR-driven hypertension and kidney phenotypes. We find that genetic dystrophin loss provides a second hit for MR-mediated cardiomyopathy in Duchenne muscular dystrophy model mice, as aldosterone worsens fibrosis, mass and dysfunction phenotypes. Vamorolone successfully prevents MR-activated phenotypes, whereas prednisolone activates negative MR and GR effects. In conclusion, vamorolone targets dual nuclear receptors to treat inflammation and cardiomyopathy with improved safety.

Influence of glucocorticoid and mineralocorticoid receptor stimulation on task switching

The influence of stress on executive functions has been demonstrated in numerous studies and is potentially mediated by the stress-induced cortisol release. Yet, the impact of cortisol on cognitive flexibility and task switching in particular remains equivocal.In this study, we investigated the influence of pharmacological glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) stimulation, two corticosteroid receptor types known to be responsible for cortisol effects on the brain. We conducted two experiments, each with 80 healthy participants (40 women and 40 men), and tested the effect of the unspecific MR/GR agonist hydrocortisone (Experiment I) and the more specific MR agonist fludrocortisone (Experiment II) on switch costs and task rule congruency in a bivalent, cued task switching paradigm.The results did not confirm our hypotheses; we found no significant effects of our manipulations on task switching capacity, although general switching and congruency effects were observed. We discuss the absence of MR/GR-mediated effects and propose alternative mechanisms that could explain stress induced effects on task switching.