A study on the effect of cimetidine and L-carnitine on myoglobinuric acute kidney injury in male rats

Aldosterone-stimulated endothelial epithelial sodium channel (EnNaC) plays a role in cold exposure–induced hypertension in rats

Background: Previous studies have demonstrated that activated endothelial epithelial sodium channel (EnNaC) impairs vasodilatation, which contributes to salt-sensitive hypertension. Here, we investigate whether mesenteric artery (MA) EnNaC is involved in cold exposure–induced hypertension (CIH) and identify the underlying mechanisms in SD rats.

Methods: One group of rats was housed at room temperature and served as control. Three groups of rats were kept in a 4°C cold incubator for 10 h/day; among which two groups were administrated with either benzamil (EnNaC blocker) or eplerenone (mineralocorticoid receptor antagonist, MR). Blood pressure (BP), vasodilatation, and endothelial function were measured with tail-cuff plethysmography, isometric myograph, and Total Nitric Oxide (NO) Assay kit, respectively. A cell-attached patch-clamp technique, in split-open MA, was used to determine the role of EnNaC in CIH rats. Furthermore, the plasma aldosterone levels were detected using an ELISA kit; and Western blot analysis was used to examine the relative expression levels of Sgk1 and Nedd4-2 proteins in the MA of SD rats.

Results: We demonstrated that cold exposure increased BP, impaired vasodilatation, and caused endothelial dysfunction in rats. The activity of EnNaC significantly increased, concomitant with an increased level of plasma aldosterone and activation of Sgk1/Nedd4-2 signaling. Importantly, CIH was inhibited by either eplerenone or benzamil. It appeared that cold-induced decrease in NO production and impairment of endothelium-dependent relaxation (EDR) were significantly ameliorated by either eplerenone or benzamil in MA of CIH rats. Moreover, treatment of MAs with aldosterone resulted in an activation of EnNaC, a reduction of NO, and an impairment of EDR, which were significantly inhibited by either eplerenone or GSK650394 (Sgk1 inhibitor) or benzamil.

Conclusion: Activation of EnNaC contributes to CIH; we suggest that pharmacological inhibition of the MR/Sgk1/Nedd4-2/EnNaC axis may be a potential therapeutic strategy for CIH.

Impact of Acid Suppression Therapy on Renal and Survival Outcomes in Patients with Chronic Kidney Disease: A Taiwanese Nationwide Cohort Study

Histamine-2-receptor antagonist (H2RA) has shown beneficial effects on the kidney, heart, and sepsis in animal models and on the heart and COVID-19 infection in clinical studies. However, H2RAshave been used as a reference in most epidemiological studies examining the association of proton pump inhibitors (PPI) with outcomes. Therefore, we aimed to evaluate the effect of H2RA on renal and survival outcomes in chronic kidney disease (CKD) patients. We used a Taiwanese nationalhealth insurance database from 2001 to 2016 to screen 45,767 CKD patients for eligibility. We identified new users of PPI (n = 7121), H2RA (n = 48,609), and users of neither PPI nor H2RA (as controls) (n = 47,072) during follow-up, and finally created 1:1:1 propensityscore-matchedcohorts; each cohort contained 4361 patients. Participants were followed up after receivingacid-suppression agents or on the corresponding date until the occurrence of end-stage renal disease (ESRD) in the presence of competing mortality, death, or through the end of 2016. Compared toneither users, H2RAand PPI users demonstrated adjusted hazard ratios of 0.40 (95% confidence interval, 0.30–0.53) for ESRDand 0.64 (0.57–0.72) for death and 1.15 (0.91–1.45) for ESRD and 1.83 (1.65–2.03) for death, respectively. A dose-response relationship betweenH2RA use with ESRD and overall, cardiovascular, and non-cardiovascular mortality was detected. H2RA consistently provided renal and survival benefits on multivariable stratified analyses and multiple sensitivity analyses. In conclusion, dose-dependent H2RA use was associated with a reduced risk of ESRD and overall mortality in CKD patients, whereas PPI use was associated with an increased risk of overall mortality, not in a dose-dependent manner.

The implications of histamine metabolism and signaling in renal function

Inflammation is an essential part of the immune response; it has been found to be central to the disruption of kidney function in acute kidney injury, diabetic nephropathy, hypertension, and other renal conditions. One of the well‐known mediators of the inflammatory response is histamine. Histamine receptors are expressed throughout different tissues, including the kidney, and their inhibition has proven to be a viable strategy for the treatment of many inflammation‐associated diseases. Here, we provide an overview of the current knowledge regarding the role of histamine and its metabolism in the kidney. Establishing the importance of histamine signaling for kidney function will enable new approaches for the treatment of kidney diseases associated with inflammation.

Microbiome-Metabolome Signature of Acute Kidney Injury

Intestinal microbiota play a considerable role in the host’s organism, broadly affecting its organs and tissues. The kidney can also be the target of the microbiome and its metabolites (especially short-chain fatty acids), which can influence renal tissue, both by direct action and through modulation of the immune response. This impact is crucial, especially during kidney injury, because the modulation of inflammation or reparative processes could affect the severity of the resulting damage or recovery of kidney function. In this study, we compared the composition of rat gut microbiota with its outcome, in experimental acute ischemic kidney injury and named the bacterial taxa that play putatively negative or positive roles in the progression of ischemic kidney injury. We investigated the link between serum creatinine, urea, and a number of metabolites (acylcarnitines and amino acids), and the relative abundance of various bacterial taxa in rat feces. Our analysis revealed an increase in levels of 32 acylcarnitines in serum, after renal ischemia/reperfusion and correlation with creatinine and urea, while levels of three amino acids (tyrosine, tryptophan, and proline) had decreased. We detected associations between bacterial abundance and metabolite levels, using a compositionality-aware approach—Rothia and Staphylococcus levels were positively associated with creatinine and urea levels, respectively. Our findings indicate that the gut microbial community contains specific members whose presence might ameliorate or, on the contrary, aggravate ischemic kidney injury. These bacterial taxa could present perspective targets for therapeutical interventions in kidney pathologies, including acute kidney injury.

Effect of chronic L-carnitine supplementation on carnitine levels, oxidative stress and apoptotic markers in peripheral organs of adult Wistar rats

This study investigated the effects of L-carnitine supplementation on carnitine levels, oxidative stress and apoptotic markers in the stomach, kidney, liver and testis tissues in adult rats. Rats were randomized to control and L-carnitine supplemented (LCAR) groups. Control group received distilled water for 7 months by intragastric gavage and the LCAR group was given 50 mg/kg/day L-carnitine via intragastric intubation for the same period. L-carnitine concentrations and caspase-3 activity were measured by fluorometric methods while cleaved caspase-3 was determined by Western blot analysis. Bcl-2 associated X protein (Bax) and B-cell lymphoma/leukemia-2 (Bcl-2) were quantified by enzyme immunoassay and Western blot analysis. Oxygen/nitrogen species (ROS/RNS) and total antioxidant capacity (TAC) were analyzed by colorimetric assay. Tissue L-carnitine concentrations were significantly increased in the LCAR group compared to controls. Anti-apoptotic Bcl-2 levels were significantly increased while pro-apoptotic Bax was significantly decreased in LCAR group rats compared to controls. Tissue caspase-3 was significantly alleviated in the LCAR group compared to controls. L-carnitine supplementation increased TAC and decreased ROS/RNS generation in the kidney, liver, stomach and testis tissues compared to controls. Obtained data suggests that L-carnitine supplementation can potentially be used to lessen both oxidative and apoptotic progression in peripheral organs.

Protective and antioxidant effects of copper-nicotinate complex against glycerol-induced nephrotoxicity in rats

Copper-nicotinate complex (CNC) has antioxidant activities through scavenging of free radicals formed inside the body. CNC also has anti-tumor and anti-inflammatory activities. The current study was designed to determine the effect of glycerol on rat kidney function and oxidative stress as well as, the potential nephroprotective effects of CNC. Forty male Wistar rats were randomly allocated into four equal groups. The groups of rats were as follows: GI was kept under normal control conditions; GII was orally given CNC at a dose of 0.043 mg kg^-1 body weight (BW), three times/week for 4 weeks; GIII was administered glycerol (topical application) at a dose of 3.15 ml kg^-1 BW daily for 4 weeks; and GIV was given CNC and glycerol with the same dose and route. The results revealed that CNC improves the renal dysfunctions induced by glycerol by recovering the levels of urea and creatinine to normal, as well as through the antioxidant status manifested by the normalization of catalase, superoxide dismutase, reduced glutathione, and malondialdehyde levels. Moreover, by its effect as an anti-oxidant, CNC reduces the effect of glycerol on the kidney by decreasing the fibrosis, degenerative changes and necrotic changes in the renal tubules. In conclusion, CNC could alleviate the side effects that might be caused by glycerol.

The protective effect of 1alpha, 25-dihydroxyvitamin d3 and metformin on liver in type 2 diabetic rats

There is an accumulating evidence suggesting an immunomodulatory role of 1α,25(OH)₂D3. Altered 1α,25(OH)₂D3 level may play a role in the development of T2DM and contribute to the pathogenesis of liver diseases. Our study was designed to study and compare the effect of metformin and 1α,25(OH)₂D3 supplementation on liver injury in type 2 diabetic rat. Sixty male Albino rats were divided into 5 groups; group 1: control rats. the remaining rats were fed high fat diet for 2 weeks and injected with streptozotocin (35mg/kg BW, i.p.) to induce T2DM and were divided into: group 2: untreated diabetic rats, group 3: diabetic rats treated by metformin (100mg/kgBW/d, orally), group 4: diabetic rats supplemented by 1α,25(OH)₂D3 (0.5μg/kg BW, i.p.) 3 times weekly and group 5: supplemented by both 1α,25(OH)₂D3 and metformin. Eight weeks later, serum glucose and insulin levels were measured, HOMA IR was calculated, lipid profile, Ca2+, ALT and AST were estimated. Liver specimens were taken to investigate PPAR-α (regulator of lipid metabolism), NF-κB p65, caspase 3 and PCNA (proliferating cell nuclear antigen) and for histological examination. The liver enzymes were elevated in the diabetic rats and the histological results revealed an injurious effect of diabetes on the liver. 1α,25(OH)₂D3, metformin and both drugs treatment significantly improved liver enzymes as compared to the untreated rats. The improvement was associated with a significant improvement in the glycemic control, lipid profile and serum Ca2+ with a significant reduction in NF-κB p65 and caspase 3 and increased PPAR-α, and PCNA expression as compared to the untreated group. 1α,25(OH)₂D3 induced a slightly better effect as compared to metformin. Both agents together had a synergistic action and almost completely protected the liver. Histological results confirmed the biochemical findings. Our results showed a protective effect of 1α,25(OH)₂D3 and metformin on liver in diabetic rats as indicated by an improvement of the level of the liver enzymes, decreased apoptosis and increased proliferation and this was confirmed histologically, with modulating NFkB and PPAR-α. Both agents together had a synergistic effect.