Local Renin-angiotensin System Research Articles

The renin-angiotensin-aldosterone system in kidney diseases of cats and dogs.

The renin-angiotensin-aldosterone system (RAAS) has a well-established key pathophysiologic role in kidney diseases, and pharmacotherapy targeting this system is a mainstay of treatment of affected human beings, cats, and dogs. Several studies have evaluated the circulating RAAS in animals with spontaneous or experimentally induced kidney diseases. Evidence supporting the activation of this system has been demonstrated in some - but not all - studies and individuals, and the interindividual variability in circulating RAAS markers is high. Advances over the last few decades have expanded our understanding of the system, which now includes the existence of a counterbalancing "alternative" RAAS and tissular renin-angiotensin systems (RASs), the latter regulated independently of the circulating endocrine RAAS. The local RAS in the kidney, termed the intrarenal RAS, is currently recognized as an important regulator of kidney function and mediator of kidney disease. In general, information on the intrarenal RAS is lacking in cats and dogs with kidney diseases; however, existing limited data suggest its activation. Despite the inconsistent evidence for circulating RAAS activation in chronic kidney diseases, RAAS inhibitors have proven effective for the treatment of its common comorbidities, systemic arterial hypertension and renal proteinuria, in both cats and dogs. Further research of the circulating RAAS, the intrarenal RAS, and the interplay between these systems in the context of kidney diseases in companion animals might contribute to the development or refinement of future treatment strategies.

Transplantation of human umbilical cord-derived mesenchymal stem cells improves age-related ovarian functional decline via regulating the local renin–angiotensin system on inflammation and oxidative stress

BackgroundAge-related reproductive aging is a natural and irreversible physiological process, and delaying childbearing is increasingly common all over the world. Transplantation of mesenchymal stem cells (MSCs) is considered a new and effective therapy to restore ovarian function, but the relevant mechanisms remain unclear. Recently, it has been found that there is a local Renin–angiotensin system (RAS) in human ovary and it plays a key role.MethodsAfter collecting follicular fluid from women who received oocyte retrieval for pure male factor infertility, the level of RAS components in it were detected, and the correlation analysis by linear regression. Then, the in vivo experiments on female C57BL/6 mice were designed to measure ovarian function, and the transcription and translation levels of RAS pathway were detected by molecular biology methods. Moreover, the role of RAS in regulating inflammation and oxidative stress in the co-culture system were explored in in vitro experiments on KGN cells.ResultsFirst, a total of 139 samples of analyzable follicular fluid were obtained. The local RAS of ovary, which is independent of systemic RAS (P > 0.05), is affected by age (Pearson r < 0, P < 0.05) and related to ovarian function, inflammation, oxidative stress indexes and assisted reproduction laboratory outcomes (P < 0.05). Next, the ovary/body weight of aging mice decreased significantly and serum sex hormones levels changed significantly (P < 0.01). The number of functional follicles decreased, while the atresia follicles increased (P < 0.05). After MSCs transplantation, all the above measures have been partially recovered (P < 0.05). Although several RAS components in aging ovary changed, MSCs only improved the expression level of AT1R (P < 0.05). Furthermore, the secretion ability and mitochondrial membrane potential of aging KGN cells decreased, while the intracellular ROS level and the aging cells ratio increased (P < 0.01). All the above measures have been partially recovered when co-cultured with MSCs (P < 0.05). After Ang(1–7) were added into the co-culture system, the above have been more significantly restored compared with Ang II (P < 0.05). Nevertheless, there was no statistical difference in estradiol level no matter which one was added (P > 0.05).ConclusionsTogether, our findings indicate that a novel possible mechanism to explain how stem cells restore age-related ovarian functional decline.

Decrease of Prolylcarboxypeptidase Dose of Aqueous Humor is Involved in the Pathogenesis of Primary Open-Angle Glaucoma via Finetuning of the Local Ocular Renin-Angiotensin System.

In this study, we investigated the cause of the AngII dose elevation in aqueous humor of primary open-angle glaucoma (POAG) patients. Enzyme-linked immunosorbent assay (ELISA), western blotting were used to detect concentration of Angiotensin Converting Enzyme 2 (ACE2) and Prolylcarboxypeptidase (PRCP). AngII and AngII + Recombinant PRCP were injected into anterior chamber of mouse eye. Mouse Intraocular pressure (IOP) was measured every week, mouse eye sections were conducted Hematoxylin-and-Eosin (H&E) staining, Masson' staining and Immunofluorescence staining. Western blotting and Immunofluorescence staining assays to detected fibrosis of trabecular meshwork cells. Mass spectrometry was used to identify proteins of aqueous humor. PRCP dose are decreased in aqueous humor of POAG patients. There is a negative correlation between PRCP and AngII levels in aqueous humor and between PRCP levels and the IOP. PRCP treatment reverses fibrosis of trabecular meshwork (TM) and prevents IOP elevation induced by AngII. Exogenous PRCP rescues fibrosis induced by AngII in HTMCs. Proteome profiling detected 502 differentially expressed proteins. Our study found PRCP dose was decreased in POAG patients' aqueous humor, and it might cause high level of AngII. Restoration of PRCP rescued fibrosis of TM cells and ameliorated IOP in AngII treatment mouse.

Monoamine Oxidase Contributes to Valvular Oxidative Stress: A Prospective Observational Pilot Study in Patients with Severe Mitral Regurgitation.

Monoamine oxidases (MAOs), mitochondrial enzymes that constantly produce hydrogen peroxide (H2O2) as a byproduct of their activity, have been recently acknowledged as contributors to oxidative stress in cardiometabolic pathologies. The present study aimed to assess whether MAOs are mediators of valvular oxidative stress and interact in vitro with angiotensin 2 (ANG2) to mimic the activation of the renin-angiotensin system. To this aim, valvular tissue samples were harvested from 30 patients diagnosed with severe primary mitral regurgitation and indication for surgical repair. Their reactive oxygen species (ROS) levels were assessed by means of a ferrous oxidation xylenol orange (FOX) assay, while MAO expression was assessed by immune fluorescence (protein) and qRT-PCR (mRNA). The experiments were performed using native valvular tissue acutely incubated or not with angiotensin 2 (ANG2), MAO inhibitors (MAOI) and the angiotensin receptor blocker, irbesartan (Irb). Correlations between oxidative stress and echocardiographic parameters were also analyzed. Ex vivo incubation with ANG2 increased MAO-A and -B expression and ROS generation. The level of valvular oxidative stress was negatively correlated with the left ventricular ejection fraction. MAOI and Irb reduced valvular H2O2. production. In conclusion, both MAO isoforms are expressed in pathological human mitral valves and contribute to local oxidative stress and ventricular functional impairment and can be modulated by the local renin-angiotensin system.

The Angiotensin Type 1 Receptor: A Drug Target to Reduce the Risk of Organ Transplant Rejection

: Allograft rejection is one of the main problems that must be overcome. Evidence suggests a role of the local renin-angiotensin system (RAS) in the progress of chronic allograft injury. Angiotensin II, generated by the renin-angiotensin system, is well-known as a major regulator molecule to control the blood pressure and fluid system. Evidence suggests that this bioactive molecule and its receptor increase the risk of tissue injuries and organ transplant rejection through different molecular mechanisms such as activation of innate and cellular immunity, upregulation of inflammatory pathways, and accumulation of extracellular matrix by expression pro-fibrotic molecules like transforming growth factor β (TGF-β) to increase the risk of fibrosis. Based on these findings, AT1R antagonists might have therapeutic potential to prevent the risk of tissue injuries and allograft rejection by regulating immune response, inflammation pathway, and fibrogenesis to improve organ functions.

105 Fetal hypothyroidism dysregulates local hepatic and renal renin-angiotensin systems in a temporal manner

Abstract The renin-angiotensin system (RAS) is an essential endocrine system with roles in electrolyte balance, blood volume, and blood pressure. While the canonical RAS exerts systemic vasoregulatory effects through steps involving hepatic, renal, and pulmonary-derived compounds, there is also evidence of localized, independently acting RAS in organs such as the liver and kidney. Further, modulations in RAS resulting from fetal hypothyroidism have previously been documented, although the temporal specificity of this endocrine interaction is not well-characterized. Thus, the objective of the current study was to examine the time-dependency of modulations in local hepatic and renal RAS in a porcine model of fetal hypothyroidism. To achieve this, pregnant gilts (n = 24) were divided evenly into either a control (CON) or methimazole (MMI) treatment group, with the MMI group receiving 5 mgּ kg-1ּ d-1 of oral MMI treatment and the CON group receiving an equivalent sham carrier. Each group was further divided into four timepoints (n = 3/treatment at each timepoint), with treatment beginning on d 34, 45, 55, or 65 of gestation. After 21 d of treatment, and at d 55, 66, 76, and 86, respectively, the gilts were humanely euthanized, blood samples taken from all fetuses (n = 340), and thyroid, liver (LVR), and kidney (KID) collected from a subset of four fetuses per litter (n = 96). Confirmation of fetal hypothyroidism in the MMI group was accomplished via histological assessment of the thyroid and measurement of circulating thyroxine (T4) concentrations. Each MMI-treated fetus (n = 96) subset showed evidence of goitrous thyroid histology, with the absence of healthy eosinophilic colloid indicating successful disruption of the fetal hypothalamic-pituitary-thyroid axis. T4 assays performed on a similar subset of n = 96 fetuses showed that MMI treatment significantly reduced T4 concentrations within each timepoint relative to CON (P &amp;lt; 0.001 at all timepoints). Following confirmation of hypothyroidism, RNA was extracted from the fetal LVR and KID samples to allow for gene expression analysis by qPCR. Ct values were normalized, fold changes calculated using the 2-∆∆Ct method, and differences within timepoint determined using a Wilcoxon signed-rank test. AGT, the precursor to all bioactive RAS peptides, was significantly downregulated in LVR at d 66 (P = 0.014) and 76 (P &amp;lt; 0.001). ACE was significantly upregulated at d 76 in both LVR (P = 0.037) and KID (P = 0.005). No significant changes were observed for ACE2 in either tissue, or for renal REN. Finally, AGTR1, the receptor that mediates RAS effects, was significantly downregulated at d 55 in KID (P &amp;lt; 0.001) and d 76 in LVR (P = 0.023), while also being upregulated at d 86 in LVR (P = 0.033). Collectively, these results show that fetal hypothyroidism modulates RAS function in a gestational age-dependent manner, which may alter fetal development and subsequent postnatal physiology.

Abstract P394: Pre-Existing Hypertension Intensifies Blood Brain Barrier Leakage But Not Astrogliosis Or Microgliosis After Traumatic Brain Injury In Mice

The extent of brain damage accompanying traumatic brain injury (TBI) depends on the type and severity of insult and is modulated by age, sex, and comorbidities. Nearly half of all US adults suffer from hypertension. Not surprisingly, hypertension is the most common premorbid condition in people aged 50 or above hospitalized with a TBI. Hypertension has been linked to cerebrovascular damage, neuroinflammation and cognitive decline. Neurogenic hypertension is elevated blood pressure initiated by the local renin angiotensin system within the brain; often times involved in resistant hypertension (high blood pressure poorly responsive to common antihypertensives). Despite an overlap in several aspects of brain pathology induced by hypertension and triggered by TBI, little is understood about the impact of premorbid hypertension on outcomes following TBI. We hypothesize that hypertension induces mild blood-brain barrier leakiness and neuroinflammation, priming the brain for greater cerebrovascular damage after TBI. To test this hypothesis, mice were rendered hypertensive via subcutaneous infusion of 1000 ng/kg/min angiotensin-II (Ang-II) two weeks prior to and one week following induction of a moderate severity controlled cortical impact or sham injury. Vascular damage and astrocyte and microglia activation were examined using histology and immunohistochemistry. Quantification was performed using HALO image analysis software. Compared to injured normotensive mice, injured hypertensive mice exhibited significantly more IgG extravasation in the cortex denoting a potentiation of blood-brain barrier damage. Despite robust injury-induced astrogliosis and microgliosis, neither GFAP nor Iba1 immunostaining was further increased by hypertension. Microbleeds were observed more in the cortex and corpus callosum but much less in the hippocampi or thalami after injury and were equivalent in hypertensive and normotensive injured mice. This study contributes to laying the groundwork of identifying and characterizing hypertension as a significant premorbid risk factor for poor outcome after TBI and provides a logical basis for incorporation of pre-existing hypertension in preclinical models of TBI, increasing their clinical relevance and predictive validity.

Elucidating the Role of Pro-renin Receptors in Pancreatic Ductal Adenocarcinoma Progression: A Novel Therapeutic Target in Cancer Therapy.

Pancreatic cancer is a highly aggressive malignancy with a very poor prognosis. The 5- year survival in these patients is very low, and most patients develop drug resistance to current therapies, so additional studies are needed to identify the potential role of new drug targets for the treatment of pancreatic cancer. Recent investigations have been performed regarding the roles of pro-renin receptors (PRR) in the initiation and development of cancers. PRR is a component of the local renin-angiotensin system (RAS). Local tissue RAS has been known in diverse organ systems, including the pancreas. Various investigations have implicated that PRRs are associated with the upregulation of various signaling pathways, like the renin-angiotensin system pathway, PI3K/Akt/mTOR, and the Wnt-signaling pathways, to contribute to pathological conditions, including cancer. In this review, we presented an overview of the role of PRR in the progression of pancreatic adenocarcinoma.

The Role of Local Angiotensin II/Angiotensin Type 1 Receptor in Endometriosis: A Potential Target for New Treatment Approaches.

Endometriosis is a chronic inflammatory disorder described by the presence of functional endometrial-like tissues at extra-uterine locations that are related to chronic pelvic pain and infertility. Multiple molecular mechanisms, including inflammation, reactive oxygen species (ROS) generation, fibrotic reactions, and angiogenesis, are involved in the pathogenesis of endometriosis; however, the exact cause of this disorder still remains a matter of discussion. Recently, it has been shown that the local renin-angiotensin system (RAS) has been expressed in different tissues, like the gynecological tract, and alterations in its expression are associated with multiple pathological conditions like endometriosis. Angiotensin II (Ang II), as a main peptide of the RAS through angiotensin type 1 receptor (AT1R), upregulates signal transduction pathways such as nuclear factor kappa B (NF-κB), mitogen activation protein kinase (MAPK), and transforming growth factor beta (TGF-β) to promote inflammation, oxidative stress, and fibrogenesis. Angiotensin receptor blockers (ARBs) control high blood pressure, which is increased by excessive AT1R activity. Recently, it has been recognized that ARBs have tissue protective effects because of their anti-inflammatory and antifibrotic effects. In this review, we focused on the role of local Ang II/AT1R axis activity in endometriosis pathogenesis and justified the use of ARB agents as a potential therapeutic strategy to improve endometriosis.

The potential role of renin angiotensin system in acute leukemia: a narrative review.

Acute leukemias (ALs) are the most common cancers in pediatric population. There are two types of ALs: acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Some studies suggest that the Renin Angiotensin System (RAS) has a role in ALs. RAS signaling modulates, directly and indirectly, cellular activity in different cancers, affecting tumor cells and angiogenesis. Our review aimed to summarize the role of RAS in ALs and to explore future perspectives for the treatment of these hematological malignancies by modulating RAS molecules. The database including Pubmed, Scopus, Cochrane Library, and Scielo were searched to find articles about RAS molecules in ALL and in pediatric patients. The search terms were "RAS", "Acute Leukemia", "ALL", "Angiotensin-(1-7)", "Pediatric", "Cancer", "Angiotensin II", "AML". In the bone marrow, RAS has been found to play a key role in blood cell formation, affecting several processes including apoptosis, cell proliferation, mobilization, intracellular signaling, angiogenesis, fibrosis, and inflammation. Local tissue RAS modulates tumor growth and metastasis through autocrine and paracrine actions. RAS mainly acts via two molecules, Angiotensin II (Ang II) and Angiotensin (1-7) [Ang-(1-7)]. While Ang II promotes tumor cell growth and stimulates angiogenesis, Ang-(1-7) inhibits the proliferation of neoplastic cells and the angiogenesis, suggesting a potential therapeutic role of this molecule in ALL. The interaction between ALs and RAS reveals a complex network of molecules that can affect the hematopoiesis and the development of hematological cancers. Understanding these interactions could pave the way for innovative therapeutic approaches targeting RAS components.

DNA methylation-mediated 11βHSD2 downregulation drives the increases in angiotensin-converting enzyme and angiotensin II within preeclamptic placentas.

Preeclampsia (PE) is a complex human-specific complication frequently associated with placental pathology. The local renin-angiotensin system (RAS) in the human placenta, which plays a crucial role in regulating placental function, has been extensively documented. Glucocorticoids (GCs) are a class of steroid hormones. PE cases often have abnormalities in GCs levels and placental GCs barrier. Despite extensive speculation, there is currently no robust evidence indicating that GCs regulate placental RAS. This study aims to investigate these potential relationships. Plasma and placental samples were collected from both normal and PE pregnancies. The levels of angiotensin-converting enzyme (ACE), angiotensin II (Ang II), cortisol, and 11β-hydroxysteroid dehydrogenases (11βHSD) were analyzed. In PE placentas, cortisol, ACE, and Ang II levels were elevated, while 11βHSD2 expression was reduced. Interestingly, a positive correlation was observed between ACE and cortisol levels in the placenta. A significant inverse correlation was found between the methylation statuses within the 11βHSD2 gene promoter and its expression, meanwhile, 11βHSD2 expression was negatively correlated with cortisol and ACE levels. Invitro experiments using placental trophoblast cells confirmed that active GCs can stimulate ACE transcription and expression through the GR pathway. Furthermore, 11βHSD2 knockdown could enhance this activating effect. An invivo study using a rat model of intrauterine GCs overexposure during mid-to-late gestation suggested that excess GCs in utero lead to increased ACE and Ang II levels in the placenta. Collectively, this study provides the first evidence of the relationships between 11βHSD2 expression, GCs barrier, ACE, and Ang II levels in the placenta. It not only contributes to understanding the pathological features of the placental GCs barrier and RAS under PE conditions, also provides important information for revealing the pathological mechanism of PE.

The role of the brain renin-angiotensin system in Parkinson´s disease.

The renin-angiotensin system (RAS) was classically considered a circulating hormonal system that regulates blood pressure. However, different tissues and organs, including the brain, have a local paracrine RAS. Mutual regulation between the dopaminergic system and RAS has been observed in several tissues. Dysregulation of these interactions leads to renal and cardiovascular diseases, as well as progression of dopaminergic neuron degeneration in a major brain center of dopamine/angiotensin interaction such as the nigrostriatal system. A decrease in the dopaminergic function induces upregulation of the angiotensin type-1 (AT1) receptor activity, leading to recovery of dopamine levels. However, AT1 receptor overactivity in dopaminergic neurons and microglial cells upregulates the cellular NADPH-oxidase-superoxide axis and Ca2+ release, which mediate several key events in oxidative stress, neuroinflammation, and α-synuclein aggregation, involved in Parkinson's disease (PD) pathogenesis. An intraneuronal antioxidative/anti-inflammatory RAS counteracts the effects of the pro-oxidative AT1 receptor overactivity. Consistent with this, an imbalance in RAS activity towards the pro-oxidative/pro-inflammatory AT1 receptor axis has been observed in the substantia nigra and striatum of several animal models of high vulnerability to dopaminergic degeneration. Interestingly, autoantibodies against angiotensin-converting enzyme 2 and AT1 receptors are increased in PD models and PD patients and contribute to blood-brain barrier (BBB) dysregulation and nigrostriatal pro-inflammatory RAS upregulation. Therapeutic strategies addressed to the modulation of brain RAS, by AT1 receptor blockers (ARBs) and/or activation of the antioxidative axis (AT2, Mas receptors), may be neuroprotective for individuals with a high risk of developing PD or in prodromal stages of PD to reduce progression of the disease.

Adipose tissue plasticity mediated by the counterregulatory axis of the renin-angiotensin system: Role of Mas and MrgD receptors.

The renin-angiotensin system (RAS) is an endocrine system composed of two main axes: the classical and the counterregulatory, very often displaying opposing effects. The classical axis, primarily mediated by angiotensin receptors type 1 (AT1R), is linked to obesity-associated metabolic effects. On the other hand, the counterregulatory axis appears to exert antiobesity effects through the activation of two receptors, the G protein-coupled receptor (MasR) and Mas-related receptor type D (MrgD). The local RAS in adipose organ has prompted extensive research into white adipose tissue and brown adipose tissue (BAT), with a key role in regulating the cellular and metabolic plasticity of these tissues. The MasR activation favors the brown plasticity signature in the adipose organ by improve the thermogenesis, adipogenesis, and lipolysis, decrease the inflammatory state, and overall energy homeostasis. The MrgD metabolic effects are related to the maintenance of BAT functionality, but the signaling remains unexplored. This review provides a summary of RAS counterregulatory actions triggered by Mas and MrgD receptors on adipose tissue plasticity. Focus on the effects related to the morphology and function of adipose tissue, especially from animal studies, will be given targeting new avenues for treatment of obesity-associated metabolic effects.

Solitary Functioning Kidneys Attenuate Renal Hemodynamics Responses to Angiotensin II in Male But Not in Female Rats.

People with solitary functioning kidneys (SFK) are prone to renal failure with time. Accordingly, local renin angiotensin system (RAS) and renal functions in subjects with SFK may act differently compared to normal condition. This study was designed to determine the renal hemodynamics responses to angiotensin II (Ang. II) in SFK male and female rats. Fifty to sixty-day-old male and female Wistar rats were subjected to unilateral renal artery obstruction, and 28 days later basal renal hemodynamic responses to Ang. II were examined in SFK groups compared to sham groups. The findings indicated lower renal vascular resistance (RVR) and renal blood flow (RBF) responses to Ang. II in male SFK compared to sham group. Such observation was not seen in female animals. An increase in renal metabolism due to hyperfunction, especially in SFK male rats, may cause a decrease in RVR. Moreover, the lower RBF response to Ang. II may be related to alteration to Ang. II receptors in the remnant kidneys in SFK rats.

The Effect of Renin-Angiotensin System Inhibitors in Patients Undergoing Pancreatic Cancer Resection.

The local renin-angiotensin system promotes angiogenesis and proliferation via vascular endothelial growth factor or epidermal growth factor receptor expression. In this study, we aimed to evaluate the impact of angiotensin system inhibitors (ASIs) on long-term outcomes in patients undergoing surgical resection of pancreatic ductal adenocarcinoma (PDAC). A single institutional retrospective analysis was performed using the medical records of patients who underwent pancreatic resection with curative intent for PDAC between January 2005 and December 2018. Patient characteristics and surgical outcomes were compared between patients taking ASIs and those who are not. A total of 272 patients were included in the study and classified into the ASI group (n = 121) and the non-ASI group (n = 151). The median overall survival times in the ASI group and non-ASI group were 38.0 and 34.0 months ( P = 0.250), and the median recurrence-free survival times were 24.0 and 15.0 months ( P = 0.025), respectively. Multivariate analysis for recurrence-free survival identified the use of ASIs ( P = 0.020), CA19-9 level >500 IU/L ( P = 0.010), positive lymph node metastasis ( P < 0.001), and no adjuvant chemotherapy ( P < 0.001) as independent prognostic factors. The use of ASI may improve long-term outcomes after surgery for PDAC.

Lipotoxicity-Related Hematological Disorders in Obesity.

Lipotoxicity can mediate endothelial dysfunction in obesity. Altered endothelial cell phenotype during the pathobiological course of the lipotoxicity may lead to hemostatic abnormalities, which is a hallmark of several hematological disorders. Impaired hemostasis could also be directly related to numerous metabolic diseases such as hypertension, diabetes, and atherosclerosis. On the other hand, the local hematopoietic bone marrow (BM) renin-angiotensin system (RAS) contributes to the development of atherosclerosis via acting on the lipotoxicity processes. Local BM RAS, principally an autocrine/paracrine/intracrine hematological system, is located at the crossroads of cellular regulation, molecular interactions, and lipotoxicity-mediated vascular endothelial dysfunction. The positive regulatory role of plasma LDL on AT1 receptor-mediated hematopoietic stem cell (HSC) differentiation and the production of pro-atherogenic monocytes have been described. LDL-regulated HSC function may explain in part hypercholesterolemia-induced inflammation as well as the anti-inflammatory and anti-atherosclerotic effects of AT1 receptor blockers. The role of local adipose tissue RAS is directly related to the pathogenesis of metabolic derangements in obesity. There may be a crosstalk between local BM RAS and local adipose tissue RAS at the genomics and transcriptomics levels. This chapter aims to review hematological alterations propagating the pathological influences of lipotoxicity on the vascular endothelium.

Angiotensin Converting Enzyme Inhibitors: Interaction Issues in Patients with Glaucoma and Arterial Hypertension. Review

The purpose of the review is to evaluate the interaction of angiotensin-converting enzyme inhibitors in patients with glaucoma and concomitant arterial hypertension using literature data. Glaucoma is the main cause of blindness and visual impairment, as well as the main cause of irreversible blindness worldwide. Pharmacotherapy, laser or surgical treatments are used to reduce IOP levels, as well as prevent deterioration of visual field defects. However, 40 % of patients develop glaucomatous neuropathy despite ongoing therapy. This prompts the investigation of alternative causes of damage to the optic nerve, and abnormal blood pressure levels, both too low and too high, are considered as a possible risk factor. Arterial hypertension occurs in 48–65 % of patients with glaucoma and is the most common systemic disease in patients with glaucoma. Currently, angiotensin converting enzyme (ACE) inhibitors are considered the “gold standard” in the treatment of arterial hypertension, in the pathogenesis of which activation of the renin-angiotensin system (RAS) plays an important role. The renin-angiotensin system (RAS) is a hormonal system responsible for regulating blood pressure and fluid and electrolyte balance in the body. Local tissue-specific RAS were found, including in the structures of the eyeball: cornea, aqueous humor, iris, ciliary body, vitreous body, retina. These data indicate that the local RAS plays an important role in the regulation of the physiology of the eye and may become a target in the development of new antiglaucoma drugs. Animal studies, as well as studies in various patient groups, show that systemic antihypertensive drugs that inhibit the RAS, such as ACE inhibitors, reduce IOP. These studies support the concept that RAS inhibitory drugs may be potential antiglaucoma drugs in the future, as ACE inhibitors can improve the outflow of intraocular fluid, thereby reducing IOP.

Exogenous Nucleotides Ameliorate Age-Related Decline in Testosterone in Male Senescence-Accelerated Mouse Prone-8 (SAMP8) Mice by Modulating the Local Renin-Angiotensin System Antioxidant Pathway.

In older men, an age-related decline in testosterone is closely associated with various adverse health outcomes. With the progression of aging, hyperactivation of the local renin-angiotensin system (RAS) and oxidative stress increase in the testis. The regulation of RAS antioxidants may be a target to delay testicular aging and maintain testosterone levels. Exogenous nucleotides (NTs) have anti-aging potential in several systems, but there are no studies of their effects on the reproductive system. In our study, we examined the effects of exogenous NTs on testosterone synthesis and explored possible mechanisms of action. Therefore, senescence-accelerated mouse prone-8 (SAMP8) mice and senescence-accelerated mouse resistant 1 (SAMR1) were used in the experiment, and they were randomly divided into an NTs free group (NTs-F), a normal control group (control), a low-dose NTs group (NTs-L), a middle-dose NTs (NTs-M), a high-dose NTs group (NTs-H) and SAMR1 groups, and the testis of the mice were collected for testing after 9 months of intervention. The results showed that exogenous NTs could increase the testicular organ index in mice during aging, and delayed the age-associated decline in testosterone levels in SAMP8 male mice, possibly by modulating the local RAS antioxidant pathway and reducing oxidative stress to protect the testis. The present study provides new research clues for the development of preventive and therapeutic strategies for related diseases.

Diverse biological functions of the renin-angiotensin system.

The renin-angiotensin system (RAS) has been widely known as a circulating endocrine system involved in the control of blood pressure. However, components of RAS have been found to be localized in rather unexpected sites in the body including the kidneys, brain, bone marrow, immune cells, and reproductive system. These discoveries have led to steady, growing evidence of the existence of independent tissue RAS specific to several parts of the body. It is important to understand how RAS regulates these systems for a variety of reasons: It gives a better overall picture of human physiology, helps to understand and mitigate the unintended consequences of RAS-inhibiting or activating drugs, and sets the stage for potential new therapies for a variety of ailments. This review fulfills the need for an updated overview of knowledge about local tissue RAS in several bodily systems, including their components, functions, and medical implications.

Paradoxically Effects of Renin-Angiotensin System Suppression

Abstract Is any specific organ protection by blocking the renin-angiotensin system? What is the role of the renin-angiotensin system (RAS) in progressive renal disease? The renoprotective effect of ACE-inhibitors and angiotensin II (Ang II) receptor blockers is not only mediated via their renal hemodynamic effects, but also through non-hemodynamic mechanisms? What is the clinical evidence for the importance of local renin-angiotensin system (RAS)? These are several questions of a medical reality: that pharmacological blockade of reninangiotensin system (RAS) is paradoxically effective although circulating plasma renin activity (PRA) is low. An overview of the normal function of the system, as well as ramifications of its dysfunction (overactivity) and potentials for therapeutic blockade, is provided below.