Dapagliflozin Attenuates Sympathetic and Pressor Responses to Stress in Young Prehypertensive Spontaneously Hypertensive Rats

The relationship between SGLT2 and systemic blood pressure regulation

The sodium-glucose cotransporter 2 (SGLT2) is a glucose transporter that is located within the proximal tubule of the kidney's nephrons. While it is typically associated with the kidney, it was later identified in various areas of the central nervous system, including areas modulating cardiorespiratory regulation like blood pressure. In the kidney, SGLT2 functions by reabsorbing glucose from the nephron's tubule into the bloodstream. SGLT2 inhibitors are medications that hinder the function of SGLT2, thus preventing the absorption of glucose and allowing for its excretion through the urine. While SGLT2 inhibitors are not the first-line choice, they are given in conjunction with other pharmaceutical interventions to manage hyperglycemia in individuals with diabetes mellitus. SGLT2 inhibitors also have a surprising secondary effect of decreasing blood pressure independent of blood glucose levels. The implication of SGLT2 inhibitors in lowering blood pressure and its presence in the central nervous system brings to question the role of SGLT2 in the brain. Here, we evaluate and review the function of SGLT2, SGLT2 inhibitors, their role in blood pressure control, the future of SGLT2 inhibitors as antihypertensive agents, and the possible mechanisms of SGLT2 blood pressure control in the central nervous system.

Pyridostigmine attenuates hypertension by inhibiting activation of the renin-angiotensin system in the hypothalamic paraventricular nucleus

Activation of the renin-angiotensin system (RAS) triggers oxidative stress and an inflammatory response in the hypothalamic paraventricular nucleus (PVN), in turn increasing the sympathetic hyperactivity that is a major cause of hypertension. Pyridostigmine has cardioprotective effects by suppressing the RAS of myocardial tissue. However, whether pyridostigmine attenuates hypertension by inhibiting the RAS of the PVN remains unclear. We thus investigated the effect and mechanism of pyridostigmine on two-kidney one-clip (2K1C)-induced hypertension. 2K1C rats received pyridostigmine, or not, for 8 weeks. Cardiovascular function, hemodynamic parameters, and autonomic activity were measured. The PVN levels of pro-/anti-inflammatory cytokines, oxidative stress, and RAS signaling molecules were evaluated. Our results showed that hypertension was accompanied by cardiovascular dysfunction and an autonomic imbalance characterized by enhanced sympathetic but diminished vagal activity. The PVN levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), reactive oxygen species (ROS), NOX-2, and malondialdehyde (MDA) increased; those of IL-10 and superoxide dismutase (SOD) decreased. Moreover, the RAS signaling pathway was activated, as evidenced by increased levels of the angiotensin-converting enzyme (ACE), angiotensin II (Ang II), and the Ang II type 1 receptor (AT1R) and a decreased AT2R level. Pyridostigmine lowered blood pressure and improved cardiovascular function, associated with restoration of the autonomic balance. Meanwhile, pyridostigmine decreased PVN IL-6, TNF-α, ROS, NOX-2, and MDA levels and increased IL-10 and SOD levels. Additionally, pyridostigmine suppressed PVN ACE, Ang II, and AT1R levels and increased AT2R expression. Pyridostigmine attenuated hypertension by inhibiting PVN oxidative stress and inflammation induced by the RAS.

Dapagliflozin and metformin in combination ameliorates diabetic nephropathy by suppressing oxidative stress, inflammation, and apoptosis and activating autophagy in diabetic rats

Considering the effects of sodium-glucose cotransporter inhibitors and metformin on the kidneys, a combination of both agents is postulated to provide protection against diabetic nephropathy (DN). We examined the potential protective effects of dapagliflozin, metformin, and their combination on kidney injury in rats with type 2 diabetes. Diabetic (DM) rats were administered dapagliflozin (1.0 mg/kg/day), metformin (100 mg/kg/day), or a combination (dapagliflozin 0.5 mg/kg/day plus metformin 50 mg/kg/day) by oral gavage for 4 weeks. Dapagliflozin monotherapy or in combination with metformin was more effective than metformin monotherapy in attenuating renal dysfunction, improving renal organic anion transporter 3 expression, and activating renal autophagy by modulating the AMPK/mTOR/SIRT1 axis in DM rats. Interestingly, dapagliflozin monotherapy exhibited greater efficacy in suppressing renal oxidative stress in DM rats than metformin or the combination treatment. Renal and pancreatic injury scores decreased in all treatment groups. Apoptotic markers were predominantly reduced in dapagliflozin monotherapy and combination treatment groups. The low-dose combination treatment, through synergistic coordination, appeared to modulate oxidative, autophagic, and apoptotic signaling and confer significant renoprotective effects against DM-induced complications. In addition, a low dose of the combination might be beneficial to patients by avoiding the risk of side effects of the medication. Future clinical trials are necessary to study the nephroprotective effects of the combined treatment at a low dosage in patients with diabetes.

Narrative review investigating the nephroprotective mechanisms of sodium glucose cotransporter type 2 inhibitors in diabetic and nondiabetic patients with chronic kidney disease

Background and aims

Outcome trials using sodium glucose cotransporter type 2 inhibitors have consistently shown their potential to preserve kidney function in diabetic and nondiabetic patients. Several mechanisms have been introduced which may explain the nephroprotective effect of sodium glucose cotransporter type 2 inhibitors beyond lowering blood glucose. This current narrative review has the objective to describe main underlying mechanisms causing a nephroprotective effect and to show similarities as well as differences between proposed mechanisms which can be observed in patients with diabetic and nondiabetic chronic kidney disease.

Methods

We performed a narrative review of the literature on Pubmed and Embase. The research string comprised various combinations of items including "chronic kidney disease", "sodium glucose cotransporter 2 inhibitor" and "mechanisms". We searched for original research and review articles published until march, 2022. The databases were searched independently and the agreements by two authors were jointly obtained.

Results

Sodium glucose cotransporter type 2 inhibitors show systemic, hemodynamic, and metabolic effects. Systemic effects include reduction of blood pressure without compensatory activation of the sympathetic nervous system. Hemodynamic effects include restoration of tubuloglomerular feedback which may improve pathologic hyperfiltration observed in most cases with chronic kidney disease. Current literature indicates that SGLT2i may not improve cortical oxygenation and may reduce medullar oxygenation.

Conclusion

Sodium glucose cotransporter type 2 inhibitors cause nephroprotective effects by several mechanisms. However, several mediators which are involved in the underlying pathophysiology may be different between diabetic and nondiabetic patients.

Dapagliflozin Ameliorates Neural Damage in the Heart and Kidney of Diabetic Mice

(1) Background: Measures for the control of diabetes mellitus (DM) and, especially, for the control of its complications represent a main objective of the research carried out on this disease, since both mortality and morbidity relating to DM represent real problems for the health system worldwide. The aim of our study was to evaluate nervous tissue from the heart and kidneys of mice with diabetes induced by streptozotocin (STZ) in the presence or absence of dapagliflozin (DAPA) treatment. (2) Methods: For this purpose, we used 24 C 57Bl/6 male mice, aged between 8 and 10 weeks. The mice were divided into three groups: sham (DM-), control (DM+), and treated (DM+). Diabetes mellitus was induced by injecting a single intraperitoneal dose of STZ. The duration of diabetes in the mice included in our study was 12 weeks after STZ administration; then, the heart and kidneys were sampled, and nervous tissue (using the primary antibody PGP 9.5) from the whole heart, from the atrioventricular node, and from the kidneys was analyzed. (3) Results: The density of nerve tissue registered a significant decrease in animals from the control group (DM+), to a value of 0.0122 ± 0.005 mm2 nerve tissue/mm2 cardiac tissue, compared with the sham group (DM-), wherein the value was 0.022 ± 0.006 mm2 nervous tissue/mm2 cardiac tissue (p = 0.004). Treatment with dapagliflozin reduced the nerve tissue damage in the treated (DM+DAPA) group of animals, resulting in a nerve tissue density of 0.019 ± 0.004 mm2 nerve tissue/mm2 cardiac tissue; a statistically significant difference was noted between the control (DM+) and treated (DM+DAPA) groups (p = 0.046). The same trends of improvement in nerve fiber damage in DM after treatment with DAPA were observed both in the atrioventricular node and in the kidneys. (4) Conclusions. These data suggest that dapagliflozin, when used in streptozotocin-induced diabetes in mice, reduces the alteration of the nervous system in the kidneys and in the heart, thus highlighting better preservation of cardiac and renal homeostasis, independent of any reduction in the effects of hyperglycemia produced in this disease.

Neural control of the circulation during exercise in heart failure with reduced and preserved ejection fraction

Patients with heart failure with reduced (HFrEF) and preserved ejection fraction (HFpEF) exhibit severe exercise intolerance that may be due, in part, to inappropriate cardiovascular and hemodynamic adjustments to exercise. Several neural mechanisms and locally released vasoactive substances work in concert through complex interactions to ensure proper adjustments to meet the metabolic demands of the contracting skeletal muscle. Specifically, accumulating evidence suggests that disease-related alterations in neural mechanisms (e.g., central command, exercise pressor reflex, arterial baroreflex, and cardiopulmonary baroreflex) contribute to heightened sympathetic activation and impaired ability to attenuate sympathetic vasoconstrictor responsiveness that may contribute to reduced skeletal muscle blood flow and severe exercise intolerance in patients with HFrEF. In contrast, little is known regarding these important aspects of physiology in patients with HFpEF, though emerging data reveal heightened sympathetic activation and attenuated skeletal muscle blood flow during exercise in this patient population that may be attributable to dysregulated neural control of the circulation. The overall goal of this review is to provide a brief overview of the current understanding of disease-related alterations in the integrative neural cardiovascular responses to exercise in both HFrEF and HFpEF phenotypes, with a focus on sympathetic nervous system regulation during exercise.

RNA-Seq transcriptome analysis of renal tissue from spontaneously hypertensive rats revealed renal protective effects of dapagliflozin, an inhibitor of sodium-glucose cotransporter 2

Hypertensive nephropathy (HTN) is a common complication of hypertension. Although various agents for treatment of hypertension exert significant effects, there is currently no effective treatment for hypertensive nephropathy. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, such as dapagliflozin (DAPA), are a new class of hypoglycemic agents shown to improve the prognosis of patients with chronic kidney disease and diabetes mellitus. However, the mechanisms underlying the protective effects of DAPA remain unclear. RNA-sequencing (RNA-Seq)-based computational analysis was conducted to explore the transcriptomic changes to spontaneously hypertensive rats (SHRs) treated with DAPA for 8 weeks. Differentially expressed genes in SHRs were related to dysregulation of lipid metabolism, oxidation-reduction reaction, immunity and inflammation in HTN. Transcriptome analysis showed that 8 weeks of DAPA therapy exerted protective effects on the renal tissues of SHRs through the lysosomal, phagosomal, and autophagic pathways. VENN diagram analysis identified Zinc finger and BTB domain-containing 20 (Zbtb20) as the potential target of DAPA therapy. Consistent with the RNA-Seq findings, real-time quantitative PCR and immunohistochemical analyses revealed increased expression of Zbtb20 in the renal tissues of SHRs, whereas expression was decreased following 8 weeks of DAPA administration. The results of this study clarified the transcriptome signature of HTN and the beneficial effects of DAPA on renal tissues by alleviating dysregulation of metabolic processes and reducing inflammation.

RNA-Seq transcriptomic landscape profiling of spontaneously hypertensive rats treated with a sodium-glucose cotransporter 2 (SGLT2) inhibitor

BACKGROUND

Sodium-glucose co-transporter-2 inhibitor (SGLT2i) are antihyperglycemic medications that reduce cardiovascular disease (CVD) and improve chronic kidney disease prognosis in patients with diabetes mellitus. The specific impact of SGLT2i treatment on hypertensive individuals, however, remains to be established. This underscores the need for systematic efforts to profile the molecular landscape associated with SGLT2i administration.

METHODS

We conducted a detailed RNA-sequencing (RNA-Seq)-based exploration of transcriptomic changes in response to empagliflozin in eight different tissues (i.e., atrium, aorta, ventricle, white adipose, brown adipose, kidney, lung, and brain) from a male rat model of spontaneously hypertension. Corresponding computational analyses (i.e., clustering, differentially-expressed genes [DEG], and functional association) were performed to analyze these data. Blood pressure measurements, tissue staining studies and RT-qPCR were performed to validate our in silico findings.

RESULTS

We discovered that empagliflozin exerted potent transcriptomic effects on various tissues, most notably the kidney, white adipose, and lung in spontaneously hypertension rats (SHR). The functional enrichment of DEGs indicated that empagliflozin may regulate blood pressure, blood glucose and lipid homeostasis in SHR. Consistent with our RNA-Seq findings, immunohistochemistry and qPCR analyses revealed decreased renal expression of mitogen-activated protein kinase 10 (MAPK10) and decreased pulmonary expression of the proinflammatory factors Legumain and cathepsin S (CTSS) at 1 month of empagliflozin administration. Notably, immunofluorescence experiments showed increased expression of the AMP-activated protein kinases Prkaa1 and Prkaa2 in white adipose tissue of SHR following empagliflozin therapy. Furthermore, the transcriptomic signatures of the blood pressure-lowing effect by empagliflozin were experimentally validated in SHR.

CONCLUSIONS

This study provided an important resource of the effects of empagliflozin on various tissues of SHRs. We identified tissue-specific and tissue-enriched transcriptomic signatures, and uncovered the beneficial effects of empagliflozin on hypertension, weight gain and inflammatory response in validated experiments.

The effect of SGLT2i on in-hospital acute heart failure risk in acute myocardial infarction patients-a retrospective study

Background and aims

The roles of sodium-glucose cotransporter 2 inhibitor (SGLT2i) in acute heart failure (AHF) risk after acute myocardial infarction (AMI) remain unclear. In this study, we explored the correlation between SGLT2i administration and short-term in-hospital AHF risk in AMI patients.

Methods

This single-center, retrospective, and observational study included 990 AMI patients comprising 386 non-ST-segment elevation myocardial infarction (NSTEMI) and 604 segment elevation myocardial infarction (STEMI) patients enrolled from January 2019 to March 2022. Demographic information, clinical characteristics, medical treatment, and laboratory examination results during hospitalization were extracted from an electronic medical record system. The primary outcome was defined as all-cause AHF during hospitalization.

Results

In NSTEMI patients, a significantly lower proportion received SGLT2i treatment in the AHF group compared with the non-AHF group. During hospitalization, SGLT2i significantly reduced brain natriuretic peptide levels both in STEMI and NSTEMI patients. Multivariate logistic regression and stratification analyses suggested that SGLT2i is associated with reduced in-hospital AHF risk, and has a strong protective effect against AHF in NSTEMI patients with hypertension. Furthermore, SGLT2i significantly reduced the risk of in-hospital AHF for both patients with diabetes and non-diabetes.

Conclusions

SGLT2i can reduce the risk of AHF in AMI patients during hospitalization.

Pathophysiology and genetics of salt-sensitive hypertension

Most hypertensive cases are primary and heavily associated with modifiable risk factors like salt intake. Evidence suggests that even small reductions in salt consumption reduce blood pressure in all age groups. In that regard, the ACC/AHA described a distinct set of individuals who exhibit salt-sensitivity, regardless of their hypertensive status. Data has shown that salt-sensitivity is an independent risk factor for cardiovascular events and mortality. However, despite extensive research, the pathogenesis of salt-sensitive hypertension is still unclear and tremendously challenged by its multifactorial etiology, complicated genetic influences, and the unavailability of a diagnostic tool. So far, the important roles of the renin-angiotensin-aldosterone system, sympathetic nervous system, and immune system in the pathogenesis of salt-sensitive hypertension have been studied. In the first part of this review, we focus on how the systems mentioned above are aberrantly regulated in salt-sensitive hypertension. We follow this with an emphasis on genetic variants in those systems that are associated with and/or increase predisposition to salt-sensitivity in humans.