Natural medicines for acute renal failure: A review

Renoprotective Effect of Taxifolin in Paracetamol-Induced Nephrotoxicity: Emerging Evidence from an Animal Model

BACKGROUND

Taxifolin (TXF) is a flavonoid found abundantly in citrus/onion. Encouraging results on its renoprotective effect have been reported in a limited number of drug-induced nephrotoxicity animal models. The present study aimed to evaluate for the first time the potential renoprotective effects of TXF in a paracetamol (PAR)-induced nephrotoxicity rat model.

METHODS

Rats were divided into three equal groups (n = 6 animals per group). Group 1 (PAR group, PARG) received PAR diluted in normal saline by gavage (1000 mg/kg). Group 2 (TXF group, TXFG) received TXF diluted in normal saline by gavage (50 mg/kg) one hour after PAR administration. Group 3 (control group, CG) received normal saline. Twenty-four hours after PAR administration, all animals were sacrificed using high-dose anesthesia. Blood samples were collected and kidneys were removed.

RESULTS

The serum blood urea nitrogen, creatinine levels and serum malondialdehyde levels were significantly increased in the PARG. The serum glutathione peroxidase, glutathione reductase and total glutathione levels were significantly higher in the TXFG. At the same time, the kidneys of the PARG animals demonstrated tubular epithelium swelling, distension and severe vacuolar degeneration. The kidneys of the TXFG animals showed mildly dilated/congested blood vessels.

CONCLUSIONS

The TXF renoprotective effects are promising in preventing PAR-induced nephrotoxicity, mainly through antioxidant activity, and warrant further testing in future studies.

Protective effect of Cistanche deserticola on gentamicin-induced nephrotoxicity in rats

Objective

Gentamicin (GM) is a commonly used aminoglycoside antibiotic, however, renal toxicity has limited its usage. The present study was designed to evaluate the ameliorative effect of Cistanche deserticola on GM-induced nephrotoxicity in rats.

Methods

The nephrotoxicity in rats was induced by intraperitoneal administration of GM (100 mg/kg) for 10 consecutive days. Glomerular filtration rate, blood urea nitrogen, creatinine and kidney histopathology were detected to assess the GM-induced nephrotoxicity. The oxidative stress (catalase, superoxide dismutase, glutathione and malondialdehyde) was assessed. The inflammatory response (tumor necrosis factor-α, interleukin-6, myeloperoxidase and nuclear factor-kappa B) and apoptotic marker (Bax and Bcl-2) were also evaluated.

Results

The results showed that water and 75% ethanol extracts of C. deserticola (named CDW and CDE, respectively) (100, 200 and 400 mg/kg) in combination with GM could recover the reduction of glomerular filtration rate and enhance the renal endogenous antioxidant capability induced by GM. The increase in the expression of renal inflammatory cytokines (tumor necrosis factor-α and interleukin-6), nuclear protein of nuclear factor-kappa B (p65) and the activity of myeloperoxidase induced by GM was significantly decreased upon CDW or CDE treatment. In addition, CDW or CDE treatment could decrease the Bax protein expression and increase the Bcl-2 protein expression in GM-induced nephrotoxicity in rats significantly.

Conclusion

The study demonstrated that C. deserticola treatment could attenuate kidney dysfunction and structural damage in rats induced by GM through the reduction of inflammation, oxidative stress and apoptosis.

The anti-inflammatory activity of resveratrol in acute kidney injury: a systematic review and meta-analysis of animal studies

CONTEXT

Accumulated experimental evidence suggests that resveratrol (RSV) may have an effect on acute kidney injury (AKI) by inhibiting inflammation. However, the credibility of the evidence for this practice is unclear.

OBJECTIVE

This study investigated the effect of RSV on AKI and the underlying mechanism.

METHODS

We searched PubMed, EMBASE, and Web of Science from 2005 to April 2022 for controlled animal trials assessing the effect of conventional resveratrol versus placebo on renal function outcome after AKI. This study was registered within the International Prospective Register of Systematic Reviews (PROSPERO) as number CRD42022329596.

RESULTS

We retrieved 455 studies, 25 studies comprising data of 436 animals that met the inclusion criteria. Our meta-analysis suggested that RSV treatment was significantly associated with lower levels of serum creatinine (Scr) and blood urea nitrogen (BUN). The greatest effects were recorded in low-dose (<20 mg/kg/day) groups rather than in high-dose (> 20 mg/kg/day) groups. For time-response effects, subgroup analysis indicated that intervention duration of RSV can influence the treatment effect, and more beneficial effects were observed when studies had a drug administration time of <2 weeks.

DISCUSSION AND CONCLUSIONS

This systematic review of animal AKI studies showed a consistently favourable effect of RSV as compared to placebo on renal function outcomes that increased with lower TNF-α, IL-6, and IL-1β. RSV has a more beneficial effect on SA-AKI animal models than the others. When the RSV intervention dose was low (< 20 mg/kg/day) and the intervention time was <2 weeks, more benefits could be observed.

Plants with Therapeutic Potential for Ischemic Acute Kidney Injury: A Systematic Review

Acute kidney injury (AKI) is a complex condition which has an intricate pathology mostly involving hemodynamic, inflammatory, and direct toxic effects at the cellular level with high morbidity and mortality ratios. Renal ischemic reperfusion injury (RIRI) is the main factor responsible for AKI, most often observed in different types of shock, kidney transplantation, sepsis, and postoperative procedures. The RIRI-induced AKI is accompanied by increased reactive oxygen species generation together with the activation of various inflammatory pathways. In this context, plant-derived medicines have shown encouraging nephroprotective properties. Evidence provided in this systemic review leads to the conclusion that plant-derived extracts and compounds exhibit nephroprotective action against renal ischemic reperfusion induced-AKI by increasing endogenous antioxidants and decreasing anti-inflammatory cytokines. However, there is no defined biomarker or target which can be used for treating AKI completely. These plant-derived extracts and compounds are only tested in selected transgenic animal models. To develop the results obtained into a therapeutic entity, one should apply them in proper vertebrate multitransgenic animal models prior to further validation in humans.

Protective Effects of Descurainia sophia against Gentamicin Induced Nephrotoxicity in Rats

Several studies have tried to find an efficient agent to prevent or reverse gentamicin (Gm) induced acute kidney injury (AKI). In this study, we assessed the potential renal protective effects of Descurainia sophia (L.) Webb ex Prantl against Gm-induced nephrotoxicity in rats. Thirty-five male Wistar rats were categorized in five groups (n = 7 per group). Control group was treated with normal saline. In four experimental groups, the rats were initially treated with normal saline (A), 800 (B), 1600 (C) and 2400 (D) mg/kg Descurainia sophia respectively for 28 days. After that, the rats of experimental groups were treated with Gm (80 mg/Kg) for 7 consecutive days. Blood and urine markers, as well as apoptosis and histological features were determined. Serum BUN, creatinine, cholesterol, and triglycerides level, as well as urinary excretion of Na⁺ significantly increased in group A. Furthermore, Gm induced inflammatory cells infiltration, apoptosis, and renal cells injuries in rats were pretreated with normal saline (group A). However, in the rats pretreated with Descurainia sophia extract (groups B, C, and D, there were significant and dose-dependent reductions in serum BUN, creatinine, cholesterol and triglyceride, urinary Na⁺ excretion, apoptosis rate, and inflammatory cells infiltration in renal tissues. Overall, Descurainia sophia showed significant protective effects against Gm-induced AKI by alleviating biochemical and histological markers of renal toxicity.

Phytochemical, acute toxicity and renal protective appraisal of Ajuga parviflora hydromethanolic leaf extract against CCl4 induced renal injury in rats

Background

Degenerative kidney diseases are mostly associated with oxidative stress. Natural products are considered as the antioxidants enrich food that can restrict the progress of oxidative stress induced disorders. Therefore, the present study was aimed to evaluate the renal protective effect of Ajuga parviflora leaf extract in carbon tetrachloride intoxicated rats.

Methods

The hydromethanolic extract of A. parviflora leaves was obtained by extracting twice in 60% methanol. The principal bioactive constituents were detected by LC/MS analysis. Toxicity of plant extract was assessed using brine shrimp lethal toxicity test and acute toxicity model on healthy Sprague-Dawley male rats. Nephroprotective effects of plant extract were also evaluated on rats by inducing CCl₄ renal toxicity in comparison with positive control and naïve groups. The dose of A. parviflora administered to animal was 100, 200 and 300 mg/kg. All administrations were given orally on an alternate day basis for 30 days. Urine and serum biomarkers were analyzed, along with antioxidant enzymes. Finally, the DNA damages, lipid peroxides, hydrogen peroxides and nitrites were assessed in rat’s renal tissue. The histopathology alterations in renal tissues were further studied for kidney damages.

Results

The LC/MS analysis confirmed the presence of different important pharmacological compounds in A. parviflora methanolic leaf extract. The key bioactive compounds include pyocyanin, zonisamide, D Saccharic acid, altretamine, carbocyclic thromboxane A2, Sinapyl alcohol, and vitamin C. The important polypeptides identified include Lys-Tyr-Lys, His-His-Lys, Met-Asp-Arg, Phe-Val-Arg, and PyroGlu-Val-Arg. The LD₅₀ of A. parviflora was found to be > 1000 μg/mL. A. parviflora administration significantly subsides CCl₄ toxicity in rats, reduced the elevated level of RBCs, pus and epithelial cells. The abnormal elevated level of specific gravity, creatinine, urobilinogen, urea and albumin were also reduced to normal physiological level. The reduced urinary protein and pH were also normalized. The serum urobilinogen, urea and total bilirubin levels were also reversed to normal levels while the diminished albumin and total protein levels also came to normal. The important phase I and II enzyme levels were also reversed in A. parviflora administered rats. The H₂O₂, thiobarbituric acid reactive substance (TBARS) and nitrite levels were significantly decreased. Furthermore, the damaged DNA and histopathological changes in CCl₄ exposed rats were also highly significantly reversed after the administration of A. parviflora. All effects were significant (P < 0.05) and highly significant (P < 0.005) at 100 and 300 mg/kg respectively.

Conclusion

The restored urine and serum profile of various parameters to normal physiological levels suggests that the A. parviflora has potential antioxidant and repairing potential in renal disorders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03360-9.

Ameliorative impacts of Glycyrrhiza glabra root extract against nephrotoxicity induced by gentamicin in mice

Gentamicin is an effective antibiotic that has been used worldwide for many years. While considered an essential medicine by the WHO, gentamicin can also lead to severe kidney damage. This study explored the ameliorative effects of Glycyrrhiza glabra root extract on gentamicin-induced renal injury in mice. Four groups of n = 7 mice were used: (a) control; (b) G. glabra-only; (c) gentamicin-only; and (d) gentamicin plus G. glabra. Kidney samples were tested for: antioxidant enzyme activity (superoxide dismutase [SOD] and glutathione peroxidase [Gpx]); expression of HO-1 and nuclear factor erythroid 2-related factor 2 genes; expression of Cox-2 and Bax; cytokine levels (IL-1β, and IL-6); histopathological anomalies; and standard renal functional component levels (creatinine, urea, and blood urea nitrogen). The effects of gentamicin were generally reversed or normalized following treatment with G. glabra root extract. Gentamicin decreased Gpx and SOD parameters and increased IL-1 β and IL-6 levels, but these returned to normal in the G. glabra-treated group. Gentamicin upregulated tissue levels of Cox-2 and Bax, and downregulated HO-1 and Nrf-2 expression but again, and these levels returned to normal in the group treated with G. glabra. Mice that had received gentamicin exhibited acute renal blood vessel congestion, focal interstitial round cell aggregation, and hydropic degeneration of renal tubular epithelium. However, those that had also received G. glabra showed a normal histopathology. Findings from this study indicate that in mouse models, gentamicin-induced kidney damage can be reversed or ameliorated by administering G. glabra, so it can be considered as an effective complimentary therapy.

Using circulating O-sulfotyrosine in the differential diagnosis of acute kidney injury and chronic kidney disease

Background

Sulfation of tyrosine, yielding O-sulfotyrosine, is a common but fixed post-translational modification in eukaryotes. Patients with increased circulating O-sulfotyrosine levels experience a faster decline in renal function with progression to end-stage renal disease (ESRD). In the present study, we measured serum O-sulfotyrosine levels in individuals with chronic kidney disease (CKD) and acute kidney injury (AKI) to explore its ability to differentiate AKI from CKD.

Methods

A total of 135 patients (20 with AKI and 115 with CKD) were recruited prospectively for liquid chromatography-mass spectrometry assessment of circulating O-sulfotyrosine. We also studied C57BL/6 mice with CKD after 5/6 nephrectomy (Nx). Blood samples were drawn from the tail vein on Day 1, 3, 5, 7, 14, 30, 60, and 90 after CKD. Serum separation and characterization of creatinine, blood urea nitrogen (BUN), and O-sulfotyrosine was performed. Thus, the time-concentration curves of the O-sulfotyrosine level demonstrate the variation of kidney dysfunction.

Results

The serum levels of O-sulfotyrosine were markedly increased in patients with CKD compared with AKI. Median O-sulfotyrosine levels in CKD patients versus AKI, respectively, were as follows:243.61 ng/mL(interquartile range [IQR] = 171.90–553.86) versus 126.55 ng/mL (IQR = 48.19–185.03, P = 0.004). In patients with CKD, O-sulfotyrosine levels were positively correlated with creatinine, BUN, and Cystatin C (r = 0.63, P < 0.001; r = 0.49, P < 0.001; r = 0.61, P < 0.001, respectively) by the multivariate linear regression analysis (β = 0.71, P < 0.001; β = 0.40, P = 0.002; β = 0.73, P < 0.001, respectively). However, this association was not statistically significant in patients with AKI (r = − 0.17, P = 0.472; r = 0.11, P = 0.655; r = 0.09, P = 0.716, respectively). The receiver operating characteristic (ROC) analysis illustrated that the area under the curve was 0.80 (95% confidence interval [CI] 0.71–0.89; P < 0.001) and the optimal cut-off value of serum O-sulfotyrosine suggesting AKI was < 147.40 ng/mL with a sensitivity and specificity of 80.90 and 70.00% respectively. In animal experiments, serum levels of O-sulfotyrosine in mice were elevated on Day 7 after 5/6 nephrectomy (14.89 ± 1.05 vs. 8.88 ± 2.62 ng/mL, P < 0.001) until Day 90 (32.65 ± 5.59 vs. 8.88 ± 2.62 ng/mL, P < 0.001).

Conclusion

Serum O-sulfotyrosine levels were observed correlated with degrading renal function and in CKD patients substantially higher than those in AKI patients. Thus serum O-sulfotyrosine facilitated the differential diagnosis of AKI from CKD.

Protective Effect of Hydroalcoholic Extract of Stachys pilifera on Oxidant-Antioxidant Status in Renal Ischemia/Reperfusion Injuries in Male Rats

Background

Renal ischemia-reperfusion (I/R) has a pivotal role in the progression of acute renal failure. Reactive oxygen species are considered the major constituents involved in the biochemical and pathophysiological changes that were shown during kidney I/R. The purpose of this study was to examine the renoprotective effects of Stachys pilifera ethanolic extract on oxidant-antioxidant status in renal I/R-injuries in male rats. Material and methods. Twenty-one male Wistar rats were arbitrarily distributed into 3 groups: sham control (SC), I/R, and I/R + Stachys pilifera ethanolic extract (500 mg/kg). The artery and vein of the right kidney were completely blocked, and the right kidney was completely removed in all groups. Then, the left kidney artery was blocked with suture thread for 30 minutes in only I/R and I/R + SP extract groups. Kidney function indices, oxidative stress markers, and hematoxylin and eosin staining were investigated in the plasma and kidney tissues.

Results

It was shown that the urine Na and K, fractional excretion of Na and K, and protein carbonyl content markedly increased in the merely I/R group as compared to SC rats, while the administration of SP extract markedly reduced these indices (P < 0.05). Also, glomerular filtration rate and total thiol meaningfully reduced in the I/R rats in contrast to the SC group, while the treatment with SP extract markedly augmented these indices (P < 0.05). However, in agreement with renal function tests, SP extract had no significant effects on histopathological examinations.

Conclusion

It seems that SP extract employs renoprotective effects on renal damage induced by I/R, possibly by improving of oxidant-antioxidant status in favor of the antioxidant system.

Preventing contrast-induced nephropathy (CIN) with herbal medicines: A review

OBJECTIVES

Currently, the use of iodinated contrast media in diagnostic imaging has been increased in clinical medicine. Contrast-induced nephropathy (CIN) is an important adverse effect of contrast media injection. According to the significant role of oxidative stress in the pathophysiology of CIN, different herbal antioxidants have been used for the prevention of nephropathy in different studies. In this review, we discussed the preventive effects of herbal medicine and natural products against CIN.

METHODS

We searched the electronic databases or search engines including PubMed, Scopus, ISI, Google Scholar with search terms such as "Contrast-induced nephropathy" and "Herbal medicine," "Contrast acute kidney injury" AND "natural products" and similar headings such as plant and extract.

RESULTS

Known medicinal plants and active ingredients such as green tea, ginger, garlic, silymarin, curcumin, resveratrol, and thymoquinone have been examined for prophylactic effects or treatment of contrast media nephropathy.

CONCLUSION

Herbal medicines have promising effects in the laboratory-based studies for the prevention and/or treatment of CIN. However, more practical and completed clinical trials are needed to investigate the clinical benefits of natural products against CIN.

Luteolin Attenuates Glycerol-Induced Acute Renal Failure and Cardiac Complications Through Modulation of Kim-1/NF-κB/Nrf2 Signaling Pathways

Acute renal failure (ARF) has been documented as a life-threatening disease with high morbidity and mortality. We investigated the protective effect of Luteolin against ARF. In this study, forty-male Wistar albino rats were randomly divided into four groups (n = 10). Group A received normal saline. Group B received glycerol (10 ml/kg BW, 50% v/v in sterile saline, i.m.). Groups C and D were pretreated with Luteolin 100 and 200 mg/kg for 7 days, and thereafter administered Glycerol (10 ml/kg BW, 50% v/v in sterile saline, i.m.). Administration of glycerol significantly increased systolic blood pressure, diastolic blood pressure and mean arterial pressure. Renal protein carbonyl and xanthine oxidase increased significantly while significant reduction in the activity of renal glutathione peroxidase, glutathione S-transferase and glutathione reductase was observed in the glycerol intoxicated rats. Furthermore, administration of glycerol led to significant increases in serum creatinine and blood urea nitrogen together with reduction in nitric oxide (NO) bioavailability. Immunohistochemistry revealed that glycerol intoxication enhanced expressions of kidney injury molecule 1, nuclear factor kappa beta and cardiac troponin (CTnI). However, Luteolin pretreatment normalized blood pressure, reduced markers of oxidative stress, renal damage, and improved NO bioavailability. Luteolin also downregulated the expressions of kidney injury molecule 1, nuclear factor kappa beta and cardiac troponin. Together, Luteolin might open a novel therapeutic window for the treatment of acute renal failure and cardiac complication.

Protective effects of D-005, a lipid extract from Acrocomia crispa fruits, against ischemia/reperfusion-induced acute kidney injury in rats

Background

Acute kidney injury (AKI) induced by renal ischemia/reperfusion (IR) is associated with enhanced production of reactive oxygen species in renal tissues. D-005, a lipid extract obtained from Acrocomia crispa fruit, has previously shown antioxidant effects. The aim of this work was to evaluate the effects of D-005 on renal IR-induced AKI in rats.

Methods

Rats were randomized into seven groups including a negative control group (vehicle) without AKI and six groups with renal IR-induced AKI as follows: a positive control (vehicle); D-005 treatment at 25, 100, 200, or 400 mg/kg; and dexamethasone at 3 mg/kg. All treatments were orally administered as single doses 1 hour before AKI induction. Biomarkers (serum creatinine, urea, and uric acid concentrations), oxidative variables, and histopathological AKI changes were evaluated in blood and kidney tissues.

Results

All D-005 doses protected against IR-induced AKI in rats by significantly decreasing biomarkers and histopathological AKI changes as assessed by reduced serum concentrations of creatinine, urea, and uric acid. In addition, all D-005 doses decreased tubular damage, as shown by fewer detached cells and casts in the tubular lumen. D-005 reversed oxidation disturbance markers by decreasing malondialdehyde and sulfhydryl group concentrations in plasma and in kidney homogenates and by increasing kidney catalase activity. Dexamethasone, the reference substance, protected against IR-induced AKI in rats by reducing biochemical and histological variables of renal damage in a similar manner.

Conclusion

Administration of single oral doses of D-005 markedly and significantly protected against renal IR-induced AKI, possibly due to its known antioxidant effects.

Novel applications of mass spectrometry-based metabolomics in herbal medicines and its active ingredients: Current evidence

Current evidence shows that herbal medicines could be beneficial for the treatment of various diseases. However, the complexities present in chemical compositions of herbal medicines are currently an obstacle for the progression of herbal medicines, which involve unclear bioactive compounds, mechanisms of action, undetermined targets for therapy, non-specific features for drug metabolism, etc. To overcome those issues, metabolomics can be a great to improve and understand herbal medicines from the small-molecule metabolism level. Metabolomics could solve scientific difficulties with herbal medicines from a metabolic perspective, and promote drug discovery and development. In recent years, mass spectrometry-based metabolomics was widely applied for the analysis of herbal constituents in vivo and in vitro. In this review, we highlight the value of mass spectrometry-based metabolomics and metabolism to address the complexity of herbal medicines in systems pharmacology, and to enhance their biomedical value in biomedicine, to shed light on the aid that mass spectrometry-based metabolomics can offer to the investigation of its active ingredients, especially, to link phytochemical analysis with the assessment of pharmacological effect and therapeutic potential. © 2019 Wiley Periodicals, Inc. Mass Spec Rev.

HPLC Analysis and In Vivo Renoprotective Evaluation of Hydroalcoholic Extract of Cucumis melo Seeds in Gentamicin-Induced Renal Damage

Background and objectives: Cucumis melo, of family Cucurbitaceae, has traditionally been used to treat variety of kidney disorders. However to best of our knowledge there is no scientific study available that validates its renaoprotective uses. Therefore, this study aimed to evaluate nephroprotective effects of hydroalcoholic extract of Cucumis melo seeds (CMHE) and to identify its phytoconstituents. Materials and Methods: HPLC was performed to identify key phytochemicals of CMHE. Gentamicin (100 mg/kg/day, i.p) was administered to induce nephrotoxicity in Swiss albino mice for 8 days. Gentamicin (100 mg/kg/day, i.p) and oral CMHE were co-administered to mice at doses of 250 and 500 mg/kg to evaluate protective effects of CMHE. Normal control group mice were administered normal saline. Changes in body weights, biochemical and histopathological studies were conducted to establish nephroprotective effects of CMHE. Results: HPLC analysis indicated presence of quercetin, m-coumaric acid, gallic acid, chlorogenic acid, and trans-4-hydroxy-3-methoxy cinnamic acid in CMHE. Mice treated with CMHE showed significant increase in body weight and decrease in kidney weight as compared with toxic control group. Dose-dependent significant decrease in total blood urea nitrogen, serum creatinine, serum urea, and uric acid levels were observed in CMHE-treated groups as compared with toxic control group. Histopathological analysis of CMHE-treated groups showed improvement in kidney structures as compared with toxic control group. Conclusions: Biochemical, histopathological, and phytochemical screening of hydroalcoholic extract of Cucumis melo seeds suggest that it has nephroprotective potential. Furthermore, standardization of extract against identified phytochemicals, as well as long-term toxicological studies are suggested before commencement of clinical trials.

The anti-inflammatory effects of curcumin on renal ischemia-reperfusion injury in rats

The present study aimed to explore the protective mechanism of curcumin-precondition in renal ischemia-reperfusion (I/R) injury. Thirty male SD rats were randomly equally divided into Sham, IRI, and Curcumin groups (n = 10). The model of IRI was induced by clamping the left renal artery for 45 min followed by 24 h reperfusion with the contralateral nephrectomy. ELISA was used to examine the expression of Cr, BUN, IL-8, TNF-α, and IL-6 in the serum; RT-PCR was used to detect the mRNA level of IL-8,TNF-α, and IL-6 in the kidney; The morphology of kidney was examined by Periodic Acid-Schiff stain (PAS). The expression of JAK2, p-JAK2, STAT3, p-STAT3, p65, and p-p65 in kidney were detected by Western blotting. The result displayed that Curcumin pretreatment can significantly increase the expression of p-JAK2 and p-STAT3 and reduce the expression of Cr, BUN, IL-8, TNF-α, IL-6, and p-p65. In addition, Curcumin can attenuate the kidney pathological injury and have no effect on the expression of JAK2, STAT3, and p65. Our findings showed the protective effect of Curcumin in I/R injury is associated with suppressing NF-κB mediating inflammation by activating JAK2/STAT3 signal pathway.

G protein-coupled estrogen receptor activation improves contractile and diastolic functions in rat renal interlobular artery to protect against renal ischemia reperfusion injury

OBJECTIVE

This work aimed to investigate whether G protein-coupled estrogen receptor (GPER) can improve the renal interlobular artery vascular function by increasing the NO content, thereby protecting against renal ischemia-reperfusion (IR) injury.

METHODS

This study classified ovariectomised (OVX) female Sprague-Dawley rats into OVX, OVX + IR, OVX + IR + G1 (the GPER agonist G1), OVX + IR + G1+G15 (GPER blocker) and OVX + IR + G1+L-NAME (eNOS blocker) groups. Enzyme-linked immunosorbent assay was performed to detect the estrogen levels in the body and eliminate interference from endogenous estrogens. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) and HE staining, renal function test and Paller scoring were performed to identify the successful model and detect the degree of renal and renal interlobular arteries injury. The in vitro microvascular pressure diameter measurement technique was used to detect the contraction and diastolic activities of the renal interlobular arteries in each group. Immunofluorescence technique was used to observe the localisation and expression levels of GPER and eNOS in renal interlobular arteries. The GPER and eNOS protein expression levels in each group were detected by Western blot. The NO content in the serum of each group was detected by the nitrate reductase method.

RESULT

After OVX, the estrogen level in the body decreased significantly (P < 0.01), and TUNEL staining showed a significant increase in the degree of renal tubular epithelial cell apoptosis in the IR group. Serum creatinine (SCr) and blood urea nitrogen (BUN) levels were significantly increased in the IR group (P < 0.01), and the Paller score showed significantly increased kidney damage. When performing drug treatment, the G1 intervention group significantly decreased serum BUN and SCr levels after IR injury (P < 0.01). The Paller score showed significantly decreased the degree of renal injury (P < 0.01). After IR, the renal interlobular artery contraction rate and systolic velocity of blood vessels were significantly decreased (P < 0.01). The G1 intervention group significantly restored contraction rate and systolic velocity of blood vessels (P < 0.01), and G15 and L-NAME partially reversed this effect (P < 0.01). Immunofluorescence technique showed that GPER was expressed in renal interlobular artery smooth muscle and endothelial cells. After IR injury, the GPER protein expression increased, and the eNOS protein expression decreased significantly (P < 0.01). Western blot showed that after IR injury, the GPER protein expression increased, and the eNOS protein expression decreased significantly. After G1 intervention, the GPER content did not change, and the eNOS content increased significantly (P < 0.01). After ischemia and reperfusion, the serum NO content decreased significantly, but it increased after G1 intervention. G15 and L-NAME reversed the effects of G1 to varying degrees (both at P < 0.01).

CONCLUSION

GPER may improve the renal interlobular artery vascular function by increasing the NO content, thereby protecting against renal IR injury.

Activation of Nrf2 by costunolide provides neuroprotective effect in PC12 cells

Costunolide (COS), a natural sesquiterpene lactone originally isolated from Inula helenium (Compositae), shows potent neuroprotective effects against oxidative stress-mediated injuries of PC12 cells via activating transcription factor Nrf2.