In vivo blockade of α1-adrenergic receptors mitigates stress-disturbed cAMP and cGMP signaling in Leydig cells

Biogenic amines in the testis: sources, receptors and actions

Biogenic amines are signaling molecules with multiple roles in the central nervous system and in peripheral organs, including the gonads. A series of studies indicated that these molecules, their biosynthetic enzymes and their receptors are present in the testis and that they are involved in the regulation of male reproductive physiology and/or pathology. This mini-review aims to summarize the current knowledge in this field and to pinpoint existing research gaps. We suggest that the widespread clinical use of pharmacological agonists/antagonists of these signaling molecules, calls for new investigations in this area. They are necessary to evaluate the relevance of biogenic amines for human male fertility and infertility, as well as the potential value of at least one of them as an anti-aging compound in the testis.

Small Molecule Cocktails Promote Fibroblast-to-Leydig-like Cell Conversion for Hypogonadism Therapy

Male hypogonadism arises from the inadequate production of testosterone (T) by the testes, primarily due to Leydig cell (LC) dysfunction. Small molecules possess several advantages, including high cell permeability, ease of synthesis, standardization, and low effective concentration. Recent investigations have illuminated the potential of small molecule combinations to facilitate direct lineage reprogramming, removing the need for transgenes by modulating cellular signaling pathways and epigenetic modifications. In this study, we have identified a specific cocktail of small molecules, comprising forskolin, DAPT, purmorphamine, 8-Br-cAMP, 20α-hydroxycholesterol, and SAG, capable of promoting the conversion of fibroblasts into Leydig-like cells (LLCs). These LLCs expressed key genes involved in testosterone synthesis, such as Star, Cyp11a1, and Hsd3b1, and exhibited the ability to secrete testosterone in vitro. Furthermore, they successfully restored serum testosterone levels in testosterone-castrated mice in vivo. The small molecule cocktails also induced alterations in the epigenetic marks, specifically H3K4me3, and enhanced chromosomal accessibility on core steroidogenesis genes. This study presents a reliable methodology for generating Leydig-like seed cells that holds promise as a novel therapeutic approach for hypogonadism.

Norepinephrine-stimulated HSCs secrete sFRP1 to promote HCC progression following chronic stress via augmentation of a Wnt16B/β-catenin positive feedback loop

Background

Sustained adrenergic signaling secondary to chronic stress promotes cancer progression; however, the underlying mechanisms for this phenomenon remain unclear. Hepatocellular carcinoma (HCC) frequently develops within fibrotic livers rich in activated hepatic stellate cells (HSCs). Here, we examined whether the stress hormone norepinephrine (NE) could accelerate HCC progression by modulating HSCs activities.

Methods

HCC cells were exposed to conditioned medium (CM) from NE-stimulated HSCs. The changes in cell migration and invasion, epithelial-mesenchymal transition, parameters of cell proliferation, and levels of cancer stem cell markers were analyzed. Moreover, the in vivo tumor progression of HCC cells inoculated with HSCs was studied in nude mice subjected to chronic restraint stress.

Results

CM from NE-treated HSCs significantly promoted cell migration and invasion, epithelial-mesenchymal transition (EMT), and expression of cell proliferation-related genes and cancer stem cell markers in HCC cells. These pro-tumoral effects were markedly reduced by depleting secreted frizzled related protein 1 (sFRP1) in CM. The pro-tumoral functions of sFRP1 were dependent on β-catenin activation, and sFRP1 augmented the binding of Wnt16B to its receptor FZD7, resulting in enhanced β-catenin activity. Additionally, sFRP1 enhanced Wnt16B expression, reinforcing an autocrine feedback loop of Wnt16B/β-catenin signaling. The expression of sFRP1 in HSCs promoted HCC progression in an in vivo model under chronic restraint stress, which was largely attenuated by sFRP1 knockdown.

Conclusions

We identify a new mechanism by which chronic stress promotes HCC progression. In this model, NE activates HSCs to secrete sFRP1, which cooperates with a Wnt16B/β-catenin positive feedback loop. Our findings have therapeutic implications for the treatment of chronic stress-promoted HCC progression.

β-adrenergic receptors in the up-regulation of COX2 expression and prostaglandin production in testicular macrophages: Possible relevance to male idiopathic infertility

Catecholaminergic neuronal elements (CNE) and macrophages (MACs) are increased in testes of patients with idiopathic infertility. Now, we describe an anatomical proximity between CNE and MACs, expression of specific α- and β-adrenergic receptors (ADRs) subtypes in MACs, and a positive correlation between the number of MACs and cyclooxygenase (COX2) expression - key enzyme in prostaglandin (PG) synthesis and an inflammatory marker - in testes of infertile men. To examine a potential effect of adrenergic input on COX2 expression, we used two additional experimental models: non-testicular human MACs (THP1 cell line) and non-human testicular MACs purified from adult Syrian hamsters. We found that epinephrine and norepinephrine up-regulate COX2 expression and PGD2 production through β1-and β2-ADRs. Our results demonstrate the existence of a yet unknown link between CNE and MACs in the human testis that could trigger inflammation and tissue homeostatic dysregulation associated with pathogenesis or maintenance of infertility states.

Polytropic Influence of TRIB3 rs2295490 Genetic Polymorphism on Response to Antihypertensive Agents in Patients With Essential Hypertension

Tribbles homolog 3 (TRIB3) mediating signaling pathways are closely related to blood pressure regulation. Our previous findings suggested a greater benefit on vascular outcomes in patients carrying TRIB3 (251, A > G, rs2295490) G allele with good glucose and blood pressure control. And TRIB3 (rs2295490) AG/GG genotypes were found to reduce primary vascular events in type 2 diabetic patients who received intensive glucose treatment as compared to those receiving standard glucose treatment. However, the effect of TRIB3 genetic variation on antihypertensives was not clear in essential hypertension patients. A total of 368 patients treated with conventional dosage of antihypertensives (6 groups, grouped by atenolol/bisoprolol, celiprolol, doxazosin, azelnidipine/nitrendipine, imidapril, and candesartan/irbesartan) were enrolled in our study. Genetic variations were successfully identified by sanger sequencing. A linear mixed model analysis was performed to evaluate blood pressures among TRIB3 (251, A > G) genotypes and adjusted for baseline age, gender, body mass index, systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol and other biochemical factors appropriately. Our data suggested that TRIB3 (251, A > G) AA genotype carriers showed better antihypertensive effect than the AG/GG genotype carriers [P = 0.014 for DBP and P = 0.042 for mean arterial pressure (MAP)], with a maximal reduction of DBP by 4.2 mmHg and MAP by 3.56 mmHg after azelnidipine or nitrendipine treatment at the 4th week. Similar tendency of DBP-change and MAP-change was found for imidapril (ACEI) treatment, in which marginally significances were achieved (P = 0.073 and 0.075, respectively). Against that, we found that TRIB3 (251, A > G) AG/GG genotype carriers benefited from antihypertensive therapy of ARBs with a larger DBP-change during the period of observation (P = 0.036). Additionally, stratified analysis revealed an obvious difference of the maximal blood pressure change (13 mmHg for the MAP between male and female patients with AA genotype who took ARBs). Although no significant difference in antihypertensive effect between TRIB3 (251, A > G) genotypes in patients treated with α, β-ADRs was observed, we found significant difference in age-, sex-dependent manner related to α, β-ADRs. In conclusion, our data supported that TRIB3 (251, A > G) genetic polymorphism may serve as a useful biomarker in the treatment of hypertension.

Alpha 1 adrenergic receptor-mediated inflammatory responses in human testicular peritubular cells

Stress activates the sympathetic nervous system and is linked to impaired fertility in man. We hypothesized that catecholamines by acting on testicular cells have a role in these events, possibly by fostering an inflammatory environment. The cells of the wall of seminiferous tubules, human testicular peritubular cells (HTPCs), express adrenergic receptors (ADRs) α1B, α1D, β1 and β2. A selective α1-ADR agonist, phenylephrine, increased intracellular Ca²⁺-levels in cultured HTPCs and induced COX-2, IL-6 and MCP-1 mRNA expression without affecting IL-1β mRNA. These changes were paralleled by a significant increase in the secretion of IL-6 and MCP-1. Epinephrine was also effective, but salbutamol, a selective β2-ADR agonist was not. Our results suggest that stress-associated elevation of catecholamines may be able to promote inflammatory events by targeting peritubular cells in the human testis. Blockage of α1-ADRs may therefore be a novel way to interfere with stress-related impairment of male reproductive functions.

Receptor- and cellular compartment-specific activation of the cAMP/PKA pathway by α1-adrenergic and ETA endothelin receptors

The signalling functions of many G protein-coupled receptors (GPCRs) expressed in the myocardium are incompletely understood. Among these are the endothelin receptor (ETR) family and α₁-adrenergic receptor (α₁-AR), which are thought to couple to the G protein Gαq. In this study, we used transcriptome analysis to compare the signalling networks downstream of these receptors in primary neonatal rat cardiomyocytes. This analysis indicated increased expression of target genes of cAMP responsive element modulator (CREM) after 24 h treatment with the α₁-AR agonist phenylephrine, but not the ETR agonist endothelin-1, suggesting a specific role for the α₁-AR in promoting cAMP production in cardiomyocytes. To validate the difference observed between these two GPCRs, we used heterologous expression of the receptors and genetically encoded biosensors in HEK 293 cell lines. We validated that both α_1A- and α_1B-AR subtypes were able to lead to the accumulation of cAMP in response to phenylephrine in both the nucleus and cytoplasm in a Gαs-dependent manner. However, the ETR subtype ETA did not affect cAMP levels in either compartment. All three receptors were coupled to Gαq signalling as expected. Further, we showed that activation of PKA in different compartments was α₁-AR subtype specific, with α_1B-AR able to activate PKA in the cytoplasm and nucleus and α_1A-AR only able to in the nucleus. We provide evidence for a pathway downstream of the α₁-AR, and show that distinct pools of a receptor lead to differential activation of downstream effector proteins dependent on their cellular compartment.

A genome-wide gene-by-trauma interaction study of alcohol misuse in two independent cohorts identifies PRKG1 as a risk locus

Traumatic life experiences are associated with alcohol use problems, an association that is likely to be moderated by genetic predisposition. To understand these interactions, we conducted a gene-by-environment genome-wide interaction study (GEWIS) of alcohol use problems in two independent samples, the Army STARRS (STARRS, N=16 361) and the Yale-Penn (N=8084) cohorts. Because the two cohorts were assessed using different instruments, we derived separate dimensional alcohol misuse scales and applied a proxy-phenotype study design. In African-American subjects, we identified an interaction of PRKG1 rs1729578 with trauma exposure in the STARRS cohort and replicated its interaction with trauma exposure in the Yale-Penn cohort (discovery-replication meta-analysis: z=5.64, P=1.69 × 10^-8). PRKG1 encodes cyclic GMP-dependent protein kinase 1, which is involved in learning, memory and circadian rhythm regulation. Considering the loci identified in stage-1 that showed same effect directions in stage-2, the gene ontology (GO) enrichment analysis showed several significant results, including calcium-activated potassium channels (GO:0016286; P=2.30 × 10^-5), cognition (GO:0050890; P=1.90 × 10^-6), locomotion (GO:0040011; P=6.70 × 10^-5) and Stat3 protein regulation (GO:0042517; P=6.4 × 10^-5). To our knowledge, this is the largest GEWIS performed in psychiatric genetics, and the first GEWIS examining risk for alcohol misuse. Our results add to a growing body of literature highlighting the dynamic impact of experience on individual genetic risk.

Interactive Effect of Corticosterone and Lactate on Regulation of Testosterone Production in Rat Leydig Cells

The increasing intensity of exercise enhanced corticosterone and lactate production in both humans and rodents. Our previous studies also demonstrated that lactate could stimulate testosterone production in vivo and in vitro. However, the production of testosterone in response to combined corticosterone and lactate on Leydig cells, and underlying molecular mechanisms are remained unclear. This study investigated the changes in testosterone levels of Leydig cells upon exposure to lactate, corticosterone or combination of both, and revealed the detailed mechanisms. Leydig cells were isolated from rat testes, and treated with different concentrations of lactate (2.5-20 mM), cortiosterone (10^-9 -10^-4  M) and lactate plus corticosterone. The production of testosterone were assayed by radioimmunoassay, and the key molecular proteins, including luteinizing hormone receptor (LHR), protein kinase A (PKA), steroidogenic acute regulatory protein (StAR), and cholesterol P450 side-chain cleavage enzyme (P450scc) involved in testosterone production were performed by Western blot. Results showed that testosterone levels were significantly increased with lactate, while decresed with corticosterone and lactate plus corticosterone treatment. Protein expressions of LHR and P450scc were upregulated with lactate treatment. However, PKA and P450scc were downregulated by lactate plus corticosterone treatment. This downregulation was followed by decreased testoterone levels in Leydig cells. Furthermore, acetylated cAMP, which activates testosterone production was increased with lactate, but not altered by conrtiosterone. Our findings conclude that corticosterone may interfere with lactate, and restrict lactate-stimulated testosterone production in Leydig cells. J. Cell. Physiol. 232: 2135-2144, 2017. © 2016 Wiley Periodicals, Inc.

Genome-wide association study of posttraumatic stress disorder in a cohort of Iraq-Afghanistan era veterans

BACKGROUND

Posttraumatic stress disorder (PTSD) is a psychiatric disorder that can develop after experiencing traumatic events. A genome-wide association study (GWAS) design was used to identify genetic risk factors for PTSD within a multi-racial sample primarily composed of U.S. veterans.

METHODS

Participants were recruited at multiple medical centers, and structured interviews were used to establish diagnoses. Genotypes were generated using three Illumina platforms and imputed with global reference data to create a common set of SNPs. SNPs that increased risk for PTSD were identified with logistic regression, while controlling for gender, trauma severity, and population substructure. Analyses were run separately in non-Hispanic black (NHB; n = 949) and non-Hispanic white (NHW; n = 759) participants. Meta-analysis was used to combine results from the two subsets.

RESULTS

SNPs within several interesting candidate genes were nominally significant. Within the NHB subset, the most significant genes were UNC13C and DSCAM. Within the NHW subset, the most significant genes were TBC1D2, SDC2 and PCDH7. In addition, PRKG1 and DDX60L were identified through meta-analysis. The top genes for the three analyses have been previously implicated in neurologic processes consistent with a role in PTSD. Pathway analysis of the top genes identified alternative splicing as the top GO term in all three analyses (FDR q < 3.5 × 10(-5)).

LIMITATIONS

No individual SNPs met genome-wide significance in the analyses.

CONCLUSIONS

This multi-racial PTSD GWAS identified biologically plausible candidate genes and suggests that post-transcriptional regulation may be important to the pathology of PTSD; however, replication of these findings is needed.

Pharmacological and biochemical studies on the protective effects of melatonin during stress-induced behavioral and immunological changes in relation to oxidative stress in rats

Stress is known to precipitate neuropsychiatric diseases, and depending upon its nature and intensity it can also influence the functioning of the immune system. Melatonin (N-acetyl-5-methoxy tryptamine) a pineal gland hormone and potent antioxidant is known to protect against many diseases. Effect of melatonin in stress-induced neuro-immunomodulation is not well elucidated. Therefore in the present study, the protective effects of melatonin were evaluated in restraint stress (RS)-induced behavioral and immunological changes in rats. RS for 1 h significantly reduces (i) percentage of open-arm entries and (ii) percentage of time spent on open-arm in elevated plus maze (EPM) test parameters (p < 0.01) and significant increase in MDA levels in brain homogenate when compared to non-RS control groups (p < 0.05). In immunological studies, both humoral and cell-mediated immune responses to antigen were significantly suppressed by RS for 1 h for 5 consecutive days, as evidenced by significant reduction in (i) anti-SRBC antibody titre, (ii) PFC counts, (iii) percentage change in paw volume, and (iv) Th1 (IFN-γ) and Th2 (IL-4) cytokine levels (p < 0.001 in all parameters). These RS-induced immunological changes were associated with significantly increased lipid peroxidation (MDA) levels in serum and significantly decreased activity of (i) SOD, (ii) CAT, and (iii) GSH levels in RS (X5)-exposed group (p < 0.02). Pretreatment with melatonin (10, 50, and 100 mg/kg) significantly reversed these RS-induced changes in EPM test parameters and humoral and cell-mediated immunological parameters, as well as oxidative stress markers in a dose-dependent manner by differential degrees (p < 0.001). Results are strongly suggestive of the involvement of free radicals during stress-induced neurobehavioral and immunological changes. These changes were significantly restored by melatonin pretreatment. We can conclude that melatonin may have a protective role during such stress-induced neuro-immunomodulation.

Intratesticular alpha1-adrenergic receptors mediate stress-disturbed transcription of steroidogenic stimulator NUR77 as well as steroidogenic repressors DAX1 and ARR19 in Leydig cells of adult rats

The aim of the present study was to define the role of testicular α1-adrenergic receptors (α1-ADRs) in stress-triggered adaptation of testosterone-producing Leydig cells of adult rats. Results showed that in vivo blockade of testicular α1-ADRs prevented partial recovery of circulating androgen levels registered after 10× repeated immobilization stress (10 × IMO). Moreover, α1-ADR-blockade diminished 10 × IMO-triggered recovery of Leydig cell androgen production, and abolished mitochondrial membrane potential recovery. In the same cells, 10 × IMO-induced increase in Star transcript was abolished, Lhcgr transcript decreased, while transcription of other steroidogenic proteins was not changed. α1-ADR-blockade recovered stress-induced decrease of Nur77, one of the main steroidogenic stimulator, while significantly reduced 10 × IMO-increased in the transcription of the main steroidogenic repressors, Arr19 and Dax1. In vitro experiments revealed an adrenaline-induced α1-ADR-mediated decrease in Nur77 transcription in Leydig cells. Adrenaline-induced increase of repressor Dax1 also involves ADRs in Leydig cells. Accordingly, α1-ADRs participate in some of the stress-triggered effects on the steroidogenic machinery of Leydig cells.

Prolonged in vivo administration of testosterone-enanthate, the widely used and abused anabolic androgenic steroid, disturbs prolactin and cAMP signaling in Leydig cells of adult rats

This study was designed to systematically analyze and define the effects of 1-day, 2-weeks, 10-weeks intramuscular administration of testosterone-enanthate, widely used and abused anabolic androgenic steroid (AAS), on main regulators of steroidogenesis and steroidogenic genes expression in testosterone-producing Leydig cells of adult rats. The results showed that prolonged (10-weeks) intramuscular administration of testosterone-enanthate, in clinically relevant dose, significantly increased prolactin, but decreased Prlr2 and Gnrhr in pituitary of adult rat. The levels of testosterone, Insl3, cAMP and mitochondrial membrane potential of Leydig cells were significantly reduced. This was followed by decreased expression of some steroidogenic enzymes and regulatory proteins such as Lhcgr, Prlr1/2, Tspo, Star, Cyp11a1, Cyp17a1, Dax1. Oppositely, Hsd3b1/2, Hsd3b5, Hsd17b4, Ar, Arr19 increased. In the same cells, transcriptional milieu of cAMP signaling elements was disturbed with remarkable up-regulation of PRKA (the main regulator of steroidogenesis). Increased prolactin together with stimulated transcription of Jak2/Jak3 could account for increased Hsd3b1/2 and Hsd3b5 in Leydig cells following 10-weeks in vivo treatment with testosterone-enanthate. In vitro studies revealed that testosterone is capable to increase level of Prlr1, Prlr2, Hsd3b1/2, Hsd3b5 in Leydig cells. Accordingly, testosterone-induced changes in prolactin receptor signaling together with up-regulation of PRKA, Hsd3b1/2, Hsd3b5, Ar in Leydig cells, could be the possible mechanism that contribute to the establishment of a new adaptive response to maintain homeostasis and prevent loss of steroidogenic function. Presented data provide new molecular insights into the relationship between disturbed testosterone homeostasis and mammalian reproduction and are important in terms of wide use and abuse of AASs and human reproductive health.

Molecular adaptations of testosterone-producing Leydig cells during systemic in vivo blockade of the androgen receptor

This study systematically evaluates the effects of androgen receptor (AR) blockade on molecular events in Leydig cells. Results showed that intramuscular administration of testosterone-enanthate, at clinically relevant dose, decreased testosterone in interstitial fluid and Leydig cells from adult rats. AR-blocker (Androcur) prevented this effect and testosterone-reduced Leydig cells steroidogenic capacity/activity. Testosterone-reduced expression of some steroidogenic enzymes/proteins (Tspo,StAR,Hsd3b1/2) and transcription factors (Nur77,Gata4,Dax1) was completely abrogated, while decreased expression of Star,Cyp11a1,Cyp17a1,Hsd17b4,Creb1a was partially prevented. In the same cells, increased expression of Hsd3b5/HSD3B and Ar/AR was abolished. Androcur-treatment abolished testosterone-reduced cAMP, coupled with a changed expressional milieu of cAMP signaling elements. Results from in vitro experiments suggest that some of these effects are testosterone-AR dependent, while others could be due to disturbed LH and/or other signals. Presented data provide new molecular insight into Leydig cells function and are important in terms of human reproductive health and the wide-spread use of Androcur as well as use/abuse of testosterone-enanthate.