High-salt intake accelerates functional and histological renal damage associated with renal tissue overexpression of (pro)renin receptors and AT1 receptors in spontaneously hypertensive rats

Paeonol improves renal and vascular angiotensin II type 1 receptor function via inhibiting oxidative stress in spontaneously hypertensive rats

BACKGROUND

Oxidative stress has been shown to play a critical role in the pathogenesis of hypertension. Paeonol, a major phenolic component extracted from Moutan Cortex, exerts a beneficial effect in preventing cardiovascular disease via reducing oxidative stress. The present study investigated the protective mechanism of paeonol against high blood pressure in spontaneous hypertension rats (SHRs).

METHODS

Wistar-Kyoto (WKY) rats and SHRs received vehicle or peaonol in the drinking water for 5 weeks. Blood pressure was measured by tail-cuff plethysmography and oxidative stress in kidney and vascular tissue was examined by enzyme-linked immunosorbed assay. The functions of angiotensin II type 1 receptors (AT₁R) in the kidney and mesenteric artery were measured by natriuresis and vasoconstrictor response, respectively.

RESULTS

Compared with vehicle-treated WKY rats, vehicle-treated SHRs exhibited higher blood pressure, increased oxidative stress, accompanied by exaggerated diuretic and natriuretic responses to candesartan (AT₁ receptor antagonist) and vasoconstrictor responses to angiotensin II (Ang II). Moreover, SHRs had higher ACE and AT₁R in the kidney and mesenteric artery, and higher Ang II and lower renin levels. Interestingly, paeonol treatment reduced the candesartan-induced increase in diuresis and natriuresis and vasoconstrictor responses to Ang II, and lowered blood pressure in SHRs, accompanied by reducing AT₁R protein expression in the kidney and mesenteric artery of SHR, and Ang II levels in plasma and increasing renin levels in renal cortex. In addition, these changes were associated with reducing oxidative stress.

CONCLUSIONS

The present study suggests that paeonol improves renal and vascular AT₁R functions by inhibition of oxidative stress, thus lowering blood pressure in SHRs.

Inhibition of ferroptosis ameliorates hypertensive nephropathy through p53/Nrf2/p21 pathway by Taohongsiwu decoction: Based on network pharmacology and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Hypertensive nephropathy (HN) is a complication of hypertension. Taohongsiwu decoction (THSWD) is used clinically but its application in the prevention and treatment of HN remains unelucidated.

AIM OF STUDY

This study aims to explore the potential targets and molecular mechanisms of THSWD in the treatment of HN.

MATERIALS AND METHODS

A network pharmacology approach was used to predict the components and targets of THSWD for treating HN. Animal experiments were performed to verify the network pharmacology findings.

RESULTS

205 targets were identified and regarded as potential targets of THSWD in HN treatment. Subsequently, we screened 17 hub genes and identified TP53 as the most critical one. KEGG enrichment analysis showed that p53 signaling pathway might play a significant role. In vivo experiments indicated that high-salt diets can lead to high blood pressure, kidney injury, inflammation, and fibrosis. Furthermore, the altered levels of biomarkers (Iron, malondialdehyde, catalase, ferritin, transferrin, Superoxide dismutase and Glutathione Peroxidase 4) provided evidence of ferroptosis. We found that the ferroptosis inhibitor ferrostatin-1 (Fer-1) and THSWD could significantly alleviate HN by suppressing ferroptosis. THSWD and Fer-1 treatment downregulated the protein and mRNA expression of p53, p21, RB, and CTNNB1, which were upregulated by high salt. Meanwhile, THSWD and Fer-1 reversed the downregulation of Nrf2 caused by high-salt diet.

CONCLUSIONS

Our results suggested that THSWD attenuate HN induced by a high-salt diet through inhibiting ferroptosis via the p53/Nrf2/p21 pathway.

Neuromorphic Gustatory System with Salt-Taste Perception, Information Processing, and Excessive-Intake Warning Capabilities

Emulation of the process of a biological gustatory system could benefit the reconstruction of sense of taste. Here we demonstrate the first neuromorphic gustatory system that emulates the ability of taste perception, information processing, and excessive-intake warning functions. The system integrates a chitosan-derived ion-gel sensor, SnO₂ nanowire artificial synapses, and an effect-executive unit. The system accomplish perception and encoding behaviors for taste stimulation without using complex circuits and multivariate analysis, showing short response delay (<1 s), long taste memory duration (>2 h), and a wide perceptive concentration range (0.02-6 wt % salt solution). Especially, SnO₂ NW artificial synapses have extremely small response voltage (1 mV), exceeding the biological level by orders of magnitude, representing so-far the highest sensitivity record. This work provides a promising strategy to develop bioinspired and biointegrated electronics with the intention of mimicking and restoring the functions of biological sensory systems.

Interactions between the intrarenal dopaminergic and the renin-angiotensin systems in the control of systemic arterial pressure

Systemic arterial hypertension is one of the leading causes of morbidity and mortality in the general population, being a risk factor for many cardiovascular diseases. Although its pathogenesis is complex and still poorly understood, some systems appear to play major roles in its development. This review aims to update the current knowledge on the interaction of the intrarenal renin-angiotensin system (RAS) and dopaminergic system in the development of hypertension, focusing on recent scientific hallmarks in the field. The intrarenal RAS, composed of several peptides and receptors, has a critical role in the regulation of blood pressure (BP) and, consequently, the development of hypertension. The RAS is divided into two main intercommunicating axes: the classical axis, composed of angiotensin-converting enzyme, angiotensin II, and angiotensin type 1 receptor, and the ACE2/angiotensin-(1-7)/Mas axis, which appears to modulate the effects of the classical axis. Dopamine and its receptors are also increasingly showing an important role in the pathogenesis of hypertension, as abnormalities in the intrarenal dopaminergic system impair the regulation of renal sodium transport, regardless of the affected dopamine receptor subtype. There are five dopamine receptors, which are divided into two major subtypes: the D1-like (D1R and D5R) and D2-like (D2R, D3R, and D4R) receptors. Mice deficient in any of the five dopamine receptor subtypes have increased BP. Intrarenal RAS and the dopaminergic system have complex interactions. The balance between both systems is essential to regulate the BP homeostasis, as alterations in the control of both can lead to hypertension.

Ivabradine treatment lowers blood pressure and promotes cardiac and renal protection in spontaneously hypertensive rats

Hypertension is linked to hyperpolarization-activated cyclic nucleotide-gated (HCN) function, expressed in excitable and non-excitable cells. Considering that the reduction in heart rate (HR) improves coronary perfusion and cardiac performance, ivabradine (IVA) emerged as an important drug for the treatment of cardiovascular diseases.

AIM

Evaluate if IVA chronic treatment effect can mitigate hypertension and reverse the cardiac and renal damage in SHR.

MAIN METHODS

Rats were divided into 4 groups treated for 14 days with PBS (1 ml/kg; i.p) or IVA (1 mg/kg; i.p): 1) WKY PBS; 2) SHR PBS; 3) WKY IVA; and 4) SHR IVA. The systolic blood pressure (SBP) was measured, indirectly, before and during the treatment period with IVA (day 0, 1, 7 and 11). Rats were subjected to artery cannulation for direct blood pressure (BP) measurement. Morphofunctional and gene expression were evaluated in the heart and kidneys.

KEY FINDINGS

IVA reduced SBP only in SHR on the 7th day. Direct blood pressure measurement showed that IVA chronic treatment reduced HR in the SHR. Interestingly, mean arterial pressure (MAP) was reduced in SHR IVA when compared to SHR PBS. Serum and urinary biochemical data were not altered by IVA. Moreover, IVA reduced the renal inflammatory infiltrates and increased glomerular density, besides preventing the cardiac inflammatory and hypertrophic responses.

SIGNIFICANCE

IVA treatment lowered blood pressure, improved cardiac remodeling and inflammation, as well as decreasing renal damage in SHR. Further, IVA increased renal HCN2 mRNA and reduced cardiac HCN4 mRNA.

Alamandine alleviates hypertension and renal damage via oxidative-stress attenuation in Dahl rats

Alamandine (Ala) is a novel member of the renin-angiotensin-system (RAS) family. The present study aimed to explore the effects of Ala on hypertension and renal damage of Dahl salt-sensitive (SS) rats high-salt diet-induced, and the mechanisms of Ala on renal-damage alleviation. Dahl rats were fed with high-salt diets to induce hypertension and renal damage in vivo, and HK-2 cells were treated with sodium chloride (NaCl) to induce renal injury in vitro. Ala administration alleviated the high-salt diet-induced hypertension, renal dysfunction, and renal fibrosis and apoptosis in Dahl SS rats. The HK-2 cells' damage, and the increases in the levels of cleaved (c)-caspase3, c-caspase8, and c-poly(ADP-ribose) polymerase (PARP) induced by NaCl were inhibited by Ala. Ala attenuated the NaCl-induced oxidative stress in the kidney and HK-2 cells. DETC, an inhibitor of SOD, reversed the inhibitory effect of Ala on the apoptosis of HK-2 cells induced by NaCl. The NaCl-induced increase in the PKC level was suppressed by Ala in HK-2 cells. Notably, PKC overexpression reversed the moderating effects of Ala on the NaCl-induced apoptosis of HK-2 cells. These results show that Ala alleviates high-salt diet-induced hypertension and renal dysfunction. Ala attenuates the renal damage via inhibiting the PKC/reactive oxygen species (ROS) signaling pathway, thereby suppressing the apoptosis in renal tubular cells.

Impact of high salt diets on CHOP-mediated apoptosis and renal fibrosis in a rat model

BACKGROUND

Prolonged and excessive salt intake accelerates oxidative stress in kidney tissues, which brings about ER stress. The PERK/ATF4/CHOP/BCL-2 signaling pathway has an essential role in ER stress-induced apoptosis. The present study aimed to investigate the effect of high salt diets on the development of renal fibrosis through CHOP-mediated apoptosis.

METHODS AND RESULTS

Twenty-five male Wistar rats were randomly divided into five groups (n = 5 each). Groups 1-5 were treated with 0%, 0.5%, 1%, 1.2%, 1.5% of NaCl dissolved in distilled water, respectively, for 8 weeks. To detect the degree of renal tubular damage, urinary KIM-1 was measured. The slides of renal tissues were stained via Masson's Trichrome staining methods for fibrosis detection. The relative gene expression of ATF4, CHOP, and BCl-2 in renal tissues were analyzed using the qRT-PCR method. The results revealed no significant difference between the urea, creatinine, and urine flow rate of the rats receiving different concentrations of NaCl (groups 2-5) and those of the control group (group 1). The rats treated with 1.5% NaCl (group 5) showed significant elevations in urinary KIM-1 and the mRNA level of CHOP compared to the control group. Mild renal fibrosis was also observed in group 5.

CONCLUSIONS

Excessive salt intake leads to fibrosis as it induces the PERK/ATF4/CHOP/BCL-2 signaling pathway in renal tissues. KIM-1 is detectable in urine before the impairment of renal function which can be used as a diagnostic marker to prevent the development of progressive renal failure.