Ameliorative effect of chrysin on adenine-induced chronic kidney disease in rats

Chrysin for Neurotrophic and Neurotransmitter Balance in Parkinson's Disease

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has a direct impact on the dopaminergic neurons in the substantia nigra pars compacta (SNpc), dopamine in the striatum (ST), homovanillic acid (HVA), neurotrophic factors of the SNpc, and ST regions leading to Parkinson's disease (PD). Dopaminergic neuron atrophy in the SNpc and dopamine degradation in the ST have an explicit link to disrupted homeostasis of the neurotrophic factor brain-derived neurotrophic factor (BDNF) of the SNpc and ST regions. Chrysin is a flavonoid with a pharmacological potential that directly influences neurotrophic levels as well as neurotransmitters. As a result, analysis of the altering levels of neurotransmitters such as dopamine and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), are observed via high-performance liquid chromatography (HPLC) and the confirmation of the influential role of BDNF and glial-derived neurotrophic factor (GDNF) in the homeostasis of dopamine, DOPAC, and HAV via examination of gene expression. The observation confirmed that chrysin balances the altering levels of neurotransmitters as well as neurotrophic factors. The protocols for reverse transcription-polymerase chain reaction (RT-PCR) and HPLC analysis for neurotransmitter levels from the SNpc and ST regions of acute PD mice brain-induced MPTP are described in this chapter.

Renoprotective Effect of Chrysanthemum coronarium L. Extract on Adenine-Induced Chronic Kidney Disease in Mice

Chronic kidney disease (CKD) gradually leads to loss of renal function and is associated with inflammation and fibrosis. Chrysanthemum coronarium L., a leafy vegetable, possesses various beneficial properties, including anti-oxidative, anti-inflammatory, and antiproliferative effects. In this study, we investigated the renoprotective effect of Chrysanthemum coronarium L. extract (CC) on adenine (AD)-induced CKD in mice. CKD was induced by feeding mice with an AD diet (0.25% w/w) for 4 weeks. Changes in renal function, histopathology, inflammation, and renal interstitial fibrosis were analyzed. The adenine-fed mice were characterized by increased blood urea nitrogen, serum creatinine, and histological changes, including inflammation and fibrosis; however, these changes were significantly restored by treatment with CC. Additionally, CC inhibited the expression of the inflammatory markers, monocyte chemoattractant protein-1, interleukins-6 and -1β, intercellular adhesion molecule-1, and cyclooxygenase 2. Moreover, CC suppressed the expression of the fibrotic markers, type IV collagen, and fibronectin. Furthermore, CC attenuated the expression of profibrotic genes (tumor growth factor-β and α-smooth muscle actin) in AD-induced renal injury mice. Thus, our results suggest that CC has the potential to attenuate AD-induced renal injury and might offer a new option as a renoprotective agent or functional food supplement to manage CKD.

Soluble guanylate cyclase agonist, isoliquiritigenin attenuates renal damage and aortic calcification in a rat model of chronic kidney failure

AIMS

Chronic kidney disease (CKD) is a growing fatal health problem worldwide associated with vascular calcification. Therapeutic approaches are limited with higher costs and poor outcomes. Adenine supplementation is one of the most relevant CKD models to human. Insufficient Nitric Oxide (NO)/ cyclic Guanosine Monophosphate (cGMP) signaling plays a key role in rapid development of renal fibrosis. Natural products display proven protection against CKD. Current study therefore explored isoliquiritigenin, a bioflavonoid extracted from licorice roots, potential as a natural activator for soluble Guanylate Cyclase (sGC) in a CKD rat model.

MATERIALS AND METHODS

60 male Wistar rats were grouped into Control group (n = 10) and the remaining rats received adenine (200 mg/kg, p.o) for 2 wk to induce CKD. They were equally sub-grouped into: Adenine untreated group and 4 groups orally treated by isoliquiritigenin low or high dose (20 or 40 mg/kg) with/without a selective sGC inhibitor, ODQ (1-H(1,2,4)oxadiazolo(4,3-a)-quinoxalin-1-one, 2 mg/kg, i.p) for 8 wk.

KEY FINDINGS

Long-term treatment with isoliquiritigenin dose-dependently and effectively amended adenine-induced chronic renal and endothelial dysfunction. It not only alleviated renal fibrosis and apoptosis markers but also aortic calcification. Additionally, this chalcone neutralized renal inflammatory response and oxidative stress. Isoliquiritigenin beneficial effects were associated with up-regulation of serum NO, renal and aortic sGC, cGMP and its dependent protein kinase (PKG). However, co-treatment with ODQ antagonized isoliquiritigenin therapeutic impact.

SIGNIFICANCE

Isoliquiritigenin seems to exert protective effects against CKD and vascular calcification by activating sGC, increasing cGMP and its downstream PKG.

Catalpol Attenuates Oxidative Stress and Inflammation via Mechanisms Involving Sirtuin-1 Activation and NF-κB Inhibition in Experimentally-Induced Chronic Kidney Disease

Chronic kidney disease (CKD) is a stealthy disease, and its development is linked to mechanisms including inflammation and oxidative stress. Catalpol (CAT), an iridoid glucoside from the root of Rehmannia glutinosa, is reported to manifest anti-inflammatory, antioxidant, antiapoptotic and antifibrotic properties. Hence, we studied the possible nephroprotective effects of CAT and its mechanisms in an adenine-induced (0.2% w/w in feed for 4 weeks) murine model of CKD by administering 5 mg/kg CAT to BALB/c mice for the duration of 4 weeks except during weekends. Upon sacrifice, the kidney, plasma and urine were collected and various physiological, biochemical and histological endpoints were assessed. CAT significantly ameliorated the adenine-induced altered body and kidney weight, water intake, urine volume, and concentrations of urea and creatinine in plasma, as well as the creatinine clearance and the albumin and creatinine ratio. Moreover, CAT significantly ameliorated the effect of adenine-induced kidney injury by reducing the kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, cystatin C and adiponectin. Similarly, the augmented concentrations of markers of inflammation and oxidative stress in the adenine-treated group were markedly reduced with CAT pretreatment. Furthermore, CAT prevented adenine-induced deoxyribonucleic acid damage and apoptotic activity in the kidneys. Histologically, CAT significantly reduced the formation of tubular necrosis and dilation, as well as interstitial fibrosis in the kidney. In addition to that, CAT significantly decreased the adenine-induced increase in the phosphorylated NF-κB and reversed the reduced expression of sirtuin-1 in the kidney. In conclusion, CAT exhibits salutary effects against adenine-induced CKD in mice by mitigating inflammation, oxidative stress and fibrosis via mechanisms involving sirtuin-1 activation and NF-κB inhibition. Confirmatory studies are warranted in order to consider CAT as a potent nephroprotective agent against CKD.

The protective effect of chrysin against oxidative stress and organ toxicity in rats exposed to propetamphos

The aim of this study was to investigate the protective efficacy of chrysin against propetamphos exposure. For this purpose, 2 to 3-month-old 40 male Wistar Albino rats were used. These animals were randomly assigned to four groups. The animals in the control group received the vehicle substance (corn oil) alone. Groups 2, 3 and 4 were administered with 50 mg/kg.bw/day of chrysin (in corn oil), 10 mg/kg.bw/day of propetamphos (in corn oil), and 10 mg/kg.bw/day of propetamphos plus 50 mg/kg.bw/day of chrysin, respectively, for 28 days. Some oxidative stress/lipid peroxidation parameters (MDA, SOD, CAT, GSH-Px, NO, glutathione) and serum biochemical parameters (triglyceride, cholesterol, creatinine, BUN, creatine phosphokinase, ALT, ALP and pseudocholinesterase) were analyzed in tissue/blood samples. Also, histopathological findings were observed. According to the data obtained, no significant alteration had occurred in these parameters and the histological findings in the group given chrysin alone, when compared to the control group. Significant unfavorable alterations were detected in the oxidative stress/lipid peroxidation/antioxidant status parameters, all biochemical parameters and histopathological findings of the group that received propetamphos alone. In the group that was given both chrysin and propetamphos, remedial/recovery alterations were observed in the oxidative stress/lipid peroxidation/antioxidant status values, serum biochemical parameters and histopathological findings, such that the values and histopathological findings showed partly similarity to those of the control group. In result, it is suggested that chrysin may provide protection against propetamphos exposure and propetamphos-induced organ damage in rats at a certain level.

Oxidative stress: An essential factor in the process of arteriovenous fistula failure

For more than half a century, arteriovenous fistula (AVFs) has been recognized as a lifeline for patients requiring hemodialysis (HD). With its higher long-term patency rate and lower probability of complications, AVF is strongly recommended by guidelines in different areas as the first choice for vascular access for HD patients, and its proportion of application is gradually increasing. Despite technological improvements and advances in the standards of postoperative care, many deficiencies are still encountered in the use of AVF related to its high incidence of failure due to unsuccessful maturation to adequately support HD and the development of neointimal hyperplasia (NIH), which narrows the AVF lumen. AVF failure is linked to the activation and migration of vascular cells and the remodeling of the extracellular matrix, where complex interactions between cytokines, adhesion molecules, and inflammatory mediators lead to poor adaptive remodeling. Oxidative stress also plays a vital role in AVF failure, and a growing amount of data suggest a link between AVF failure and oxidative stress. In this review, we summarize the present understanding of the pathophysiology of AVF failure. Furthermore, we focus on the relation between oxidative stress and AVF dysfunction. Finally, we discuss potential therapies for addressing AVF failure based on targeting oxidative stress.

In Vitro Assessment of Anti-inflammatory Effect of Apigenin on Renal Cell Inflammation

Objective: The aim of this study was to evaluate in vitro effect of apigenin on anti-inflammatory cytokines interleukin (IL)-10 and transforming growth factor beta (TGF-β) levels in an in vitro model of renal cell inflammation induced with lipopolysaccharide (LPS). Methods: Renal cell inflammation was formed in the African green monkey kidney cell line (Vero). Four groups as NC (negative control group, any application was not done), LPS (treatment with 10 μg/ml of lipopolysaccharide during 4 hours), API (treatment with 5 μg/ml of apigenin during 12 hours) and LPS+API (treatment with 10 μg/ml of lipopolysaccharide during 4 hours+5 μg/ml of apigenin during 12 hours) were formed. Cytotoxic effect of apigenin in Vero cells was evaluated by cell count test. Inflammation dose of lipopolysaccharide was determined by measuring Tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) concentrations in cell culture supernatants. TNF-α, IL-6, IL-10 and TGF-β concentrations in cell culture medium were measured by ELISA using ELISA test kits. Results: IL-6 and TNF-α concentrations of LPS group increased compared to NC, API and LPS+API groups (p

Evidence-based mechanistic role of chrysin towards protection of cardiac hypertrophy and fibrosis in rats

Cardiac hypertrophy is the enlargement of cardiomyocytes in response to persistent release of catecholamine which further leads to cardiac fibrosis. Chrysin, flavonoid from honey, is well known for its multifarious properties like antioxidant, anti-inflammatory, anti-fibrotic and anti-apoptotic. To investigate the cardioprotective potential of chrysin against isoproterenol (ISO), cardiac hypertrophy and fibrosis are induced in rats. Acclimatised male albino Wistar rats were divided into seven groups (n 6): normal (carboxymethyl cellulose at 0·5 % p.o.; as vehicle), hypertrophy control (ISO 3 mg/kg, s.c.), CHY15 + H, CHY30 + H & CHY60 + H (chrysin; p.o.15, 30 and 60 mg/kg respectively + ISO at 3 mg/kg, s.c.), CHY60 (chrysin 60 mg/kg in per se) and LST + H (losartan 10 mg/kg p.o. + ISO 3 mg/kg, s.c.) were treated for 28 d. After the dosing schedule on day 29, haemodynamic parameters were recorded, after that blood and heart were excised for biochemical, histological, ultra-structural and molecular evaluations. ISO administration significantly increases heart weight:body weight ratio, pro-oxidants, inflammatory and cardiac injury markers. Further, histopathological, ultra-structural and molecular studies confirmed deteriorative changes due to ISO administration. Pre-treatment with chrysin of 60 mg/kg reversed the ISO-induced damage to myocardium and prevent cardiac hypertrophy and fibrosis through various anti-inflammatory, anti-apoptotic, antioxidant and anti-fibrotic pathways. Data demonstrated that chrysin attenuated myocardial hypertrophy and prevented fibrosis via activation of transforming growth factor-beta (TGF-β)/Smad signalling pathway.

Nutrition, Immunology, and Kidney: Looking Beyond the Horizons

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is epidemic throughout the word. Despite various novel therapeutic opportunities, CKD is still associated with high morbidity and mortality. In CKD, patient's chronic inflammation is frequent and related with adverse outcomes. Both innate and adaptive immunity are dysfunctional in CKD. Therefore, it is plausible to interfere with dysfunctional immunity in these patients. In the current review, we present the updated experimental and clinical data summarizing the effects of nutritional interventions including natural products and dietary supplements on immune dysfunction in the context of CKD.

RECENT FINDINGS

Nutritional interventions including natural products and dietary supplements (e.g., curcumin, sulforaphane, resistant starch, anthocyanin, chrysin, short chain fatty acids, fish oil resistant starch) slow down the inflammation by at least 6 mechanisms: (i) decrease nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB); (ii) decrease NLR family pyrin domain containing 3 (NLRP3); (iii) decrease interleukin-1 (IL-1), decrease interleukin-6 (IL-6) secretion; (iv) decrease polymorphonuclear priming); (v) promote anti-inflammatory pathways (nuclear factor-erythroid factor 2-related factor 2 (NFR2); (vi) increase T regulatory (Tregs) cells). Natural products and dietary supplements may provide benefit in terms of kidney health. By modulation of nutritional intake, progression of CKD may be delayed.

Interleukin-33/ Suppression of Tumorigenicity 2 in Renal Fibrosis: Emerging Roles in Prognosis and Treatment

Chronic kidney disease (CKD) is a major public health problem that affects more than 10% of the population worldwide and has a high mortality rate. Therefore, it is necessary to identify novel treatment strategies for CKD. Incidentally, renal fibrosis plays a central role in the progression of CKD to end-stage renal disease (ESRD). The activation of inflammatory pathways leads to the development of renal fibrosis. In fact, interleukin-33 (IL-33), a newly discovered member of the interleukin 1 (IL-1) cytokine family, is a crucial regulator of the inflammatory process. It exerts pro-inflammatory and pro-fibrotic effects via the suppression of tumorigenicity 2 (ST2) receptor, which, in turn, activates other inflammatory pathways. Although the role of this pathway in cardiac, pulmonary, and hepatic fibrotic diseases has been extensively studied, its precise role in renal fibrosis has not yet been completely elucidated. Recent studies have shown that a sustained activation of IL-33/ST2 pathway promotes the development of renal fibrosis. However, with prolonged research in this field, it is expected that the IL-33/ST2 pathway will be used as a diagnostic and prognostic tool for renal diseases. In addition, the IL-33/ST2 pathway seems to be a new target for the future treatment of CKD. Here, we review the mechanisms and potential applications of the IL-33/ST2 pathway in renal fibrosis; such that it can help clinicians and researchers to explore effective treatment options and develop novel medicines for CKD patients.

Molecular Mechanistic Pathways Targeted by Natural Antioxidants in the Prevention and Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is the progressive loss of renal function and the leading cause of end-stage renal disease (ESRD). Despite optimal therapy, many patients progress to ESRD and require dialysis or transplantation. The pathogenesis of CKD involves inflammation, kidney fibrosis, and blunted renal cellular antioxidant capacity. In this review, we have focused on in vitro and in vivo experimental and clinical studies undertaken to investigate the mechanistic pathways by which these compounds exert their effects against the progression of CKD, particularly diabetic nephropathy and kidney fibrosis. The accumulated and collected data from preclinical and clinical studies revealed that these plants/bioactive compounds could activate autophagy, increase mitochondrial bioenergetics and prevent mitochondrial dysfunction, act as modulators of signaling pathways involved in inflammation, oxidative stress, and renal fibrosis. The main pathways targeted by these compounds include the canonical nuclear factor kappa B (NF-κB), canonical transforming growth factor-beta (TGF-β), autophagy, and Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid factor 2-related factor 2 (Nrf2)/antioxidant response element (ARE). This review presented an updated overview of the potential benefits of these antioxidants and new strategies to treat or reduce CKD progression, although the limitations related to the traditional formulation, lack of standardization, side effects, and safety.

Skeletal myopathy in CKD: a comparison of adenine-induced nephropathy and 5/6 nephrectomy models in mice

Preclinical animal models of chronic kidney disease (CKD) are critical to investigate the underlying mechanisms of disease and to evaluate the efficacy of novel therapeutics aimed to treat CKD-associated pathologies. The objective of the present study was to compare the adenine diet and 5/6 nephrectomy (Nx) CKD models in mice. Male and female 10-wk-old C57BL/6J mice (n = 5-9 mice/sex/group) were randomly allocated to CKD groups (0.2-0.15% adenine-supplemented diet or 5/6 Nx surgery) or the corresponding control groups (casein diet or sham surgery). Following the induction of CKD, the glomerular filtration rate was reduced to a similar level in both adenine and 5/6 Nx mice (adenine diet-fed male mice: 81.1 ± 41.9 µL/min vs. 5/6 Nx male mice: 160 ± 80.9 µL/min, P = 0.5875; adenine diet-fed female mice: 112.9 ± 32.4 µL/min vs. 5/6 Nx female mice: 107.0 ± 45.7 µL/min, P = 0.9995). Serum metabolomics analysis indicated that established uremic toxins were robustly elevated in both CKD models, although some differences were observed between CKD models (i.e., p-cresol sulfate). Dysregulated phosphate homeostasis was observed in the adenine model only, whereas Ca2+ homeostasis was disturbed in male mice with both CKD models. Compared with control mice, muscle mass and myofiber cross-sectional areas of the extensor digitorum longus and soleus muscles were ∼18-24% smaller in male CKD mice regardless of the model but were not different in female CKD mice (P > 0.05). Skeletal muscle mitochondrial respiratory function was significantly decreased (19-24%) in CKD mice in both models and sexes. These findings demonstrate that adenine diet and 5/6 Nx models of CKD have similar levels of renal dysfunction and skeletal myopathy. However, the adenine diet model demonstrated superior performance with regard to mortality (∼20-50% mortality for 5/6 Nx vs. 0% mortality for the adenine diet, P < 0.05 for both sexes) compared with the 5/6 Nx surgical model.NEW & NOTEWORTHY Numerous preclinical models of chronic kidney disease have been used to evaluate skeletal muscle pathology; however, direct comparisons of popular models are not available. In this study, we compared adenine-induced nephropathy and 5/6 nephrectomy models. Both models produced equivalent levels of muscle atrophy and mitochondrial impairment, but the adenine model exhibited lower mortality rates, higher consistency in uremic toxin levels, and dysregulated phosphate homeostasis compared with the 5/6 nephrectomy model.

D-Mannitol Induces a Brown Fat-like Phenotype via a β3-Adrenergic Receptor-Dependent Mechanism

The presence of brown adipocytes within white adipose tissue is associated with phenotypes that exhibit improved metabolism and proper body weight maintenance. Therefore, a variety of dietary agents that facilitate the browning of white adipocytes have been investigated. In this study, we screened a natural product library comprising 133 compounds with the potential to promote the browning of white adipocytes, and found that D-mannitol induces the browning of 3T3-L1 adipocytes by enhancing the expression of brown fat-specific genes and proteins, and upregulating lipid metabolism markers. D-mannitol also increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase 1 (ACC), suggesting a possible role in lipolysis and fat oxidation. Moreover, an increase in the expression of genes associated with D-mannitol-induced browning was strongly correlated with the activation of the β3-adrenergic receptor as well as AMPK, protein kinase A (PKA), and PPARγ coactivator 1α (PGC1α). D-mannitol effectively reduced the body weight of mice fed a high-fat diet, and increased the expression of β1-oxidation and energy expenditure markers, such as Cidea, carnitine palmityl transferase 1 (CPT1), uncoupling protein 1 (UCP1), PGC1α, and acyl-coenzyme A oxidase (ACOX1) in the inguinal white adipose tissue. Our findings suggest that D-mannitol plays a dual regulatory role by inducing the generation of a brown fat-like phenotype and enhancing lipid metabolism. These results indicate that D-mannitol can function as an anti-obesity supplement.

Tissue-Specific 1H-NMR Metabolomic Profiling in Mice with Adenine-Induced Chronic Kidney Disease

Chronic kidney disease (CKD) results in the impaired filtration of metabolites, which may be toxic or harmful to organs/tissues. The objective of this study was to perform unbiased ¹H nuclear magnetic resonance (NMR)-based metabolomics profiling of tissues from mice with CKD. Five-month-old male C57BL6J mice were placed on either a casein control diet or adenine-supplemented diet to induce CKD for 24 weeks. CKD was confirmed by significant increases in blood urea nitrogen (24.1 ± 7.7 vs. 105.3 ± 18.3 mg/dL, p < 0.0001) in adenine-fed mice. Following this chronic adenine diet, the kidney, heart, liver, and quadriceps muscles were rapidly dissected; snap-frozen in liquid nitrogen; and the metabolites were extracted. Metabolomic profiling coupled with multivariate analyses confirm clear separation in both aqueous and organic phases between control and CKD mice. Severe energetic stress and apparent impaired mitochondrial metabolism were observed in CKD kidneys evidenced by the depletion of ATP and NAD⁺, along with significant alterations in tricarboxylic acid (TCA) cycle intermediates. Altered amino acid metabolism was observed in all tissues, although significant differences in specific amino acids varied across tissue types. Taken together, this study provides a metabolomics fingerprint of multiple tissues from mice with and without severe CKD induced by chronic adenine feeding.

Impaired muscle mitochondrial energetics is associated with uremic metabolite accumulation in chronic kidney disease

Chronic kidney disease (CKD) causes progressive skeletal myopathy involving atrophy, weakness, and fatigue. Mitochondria have been thought to contribute to skeletal myopathy; however, the molecular mechanisms underlying muscle metabolism changes in CKD are unknown. We employed a comprehensive mitochondrial phenotyping platform to elucidate the mechanisms of skeletal muscle mitochondrial impairment in mice with adenine-induced CKD. CKD mice displayed significant reductions in mitochondrial oxidative phosphorylation (OXPHOS), which was strongly correlated with glomerular filtration rate, suggesting a link between kidney function and muscle mitochondrial health. Biochemical assays uncovered that OXPHOS dysfunction was driven by reduced activity of matrix dehydrogenases. Untargeted metabolomics analyses in skeletal muscle revealed a distinct metabolite profile in CKD muscle including accumulation of uremic toxins that strongly associated with the degree of mitochondrial impairment. Additional muscle phenotyping found CKD mice experienced muscle atrophy and increased muscle protein degradation, but only male CKD mice had lower maximal contractile force. CKD mice had morphological changes indicative of destabilization in the neuromuscular junction. This study provides the first comprehensive evaluation of mitochondrial health in murine CKD muscle to our knowledge and uncovers several unknown uremic metabolites that strongly associate with the degree of mitochondrial impairment.

Dietary Fermented Soy Extract and Oligo-Lactic Acid Alleviate Chronic Kidney Disease in Mice via Inhibition of Inflammation and Modulation of Gut Microbiota

Chronic kidney disease (CKD) is a global epidemic with an increasing prevalence worldwide. Effective preventive strategies are urgently needed. This study aimed to investigate the effect of nutraceutical components, a fermented soybean product (ImmuBalance, IMB) and an oligo-lactic acid product (LAP), on the prevention of adenine-induced CKD in mice. Female C57BL/6 mice were randomly assigned into following experimental groups: negative control; model control; and models treated with IMB at 250 or 1000 mg/kg body weight (BW), LAP at 1000 or 2000 mg/kg BW, and IMB/LAP combinations. The CKD model was established by intraperitoneal injection of adenine daily for 4 weeks, and treatments started 2 weeks before adenine injection and ended after 10 weeks. Compared with the model control, the treatments did not significantly alter the body weight or food intake. Both IMB and LAP, especially their combination, significantly inhibited tubular dilation, tubulointerstitial degeneration or atrophy, interstitial chronic inflammation and acute inflammation in the kidneys of CKD mice, and significantly decreased serum cystatin C levels. IMB or LAP significantly reversed CKD-associated increases of circulating and kidney levels of inflammatory cytokines, circulating levels of kidney injury biomarkers, and kidney levels of stem cell biomarkers, and significantly reversed CKD-associated reduction of cecum Clostridium leptum group. Our results suggest that dietary supplementation of IMB or LAP may significantly delay the development and/or progression of CKD.

Antidotal or protective effects of honey and one of its major polyphenols, chrysin, against natural and chemical toxicities

OBJECTIVE

Honey and its polyphenolic compounds are of main natural antioxidants that have been used in traditional medicine. The aim of this review was to identify the protective effects of honey and chrysin (a polyphenol available in honey) against the chemical and natural toxic agents.

METHOD

The scientific databases such as MEDLINE, PubMed, Scopus, Web of Science and Google Scholar were searched to identify studies on the antidotal effects of honey and chrysin against toxic agents.

RESULTS

This study found that honey had protective activity against toxic agents-induced organ damages by modulating oxidative stress, inflammation, and apoptosis pathways. However, clinical trial studies are needed to confirm the efficacy of honey and chrysin as antidote agents in human intoxication.

CONCLUSION

Honey and chrysin may be effective against toxic agents. (www.actabiomedica.it).

Chronic kidney disease exacerbates ischemic limb myopathy in mice via altered mitochondrial energetics

Chronic kidney disease (CKD) substantially increases the severity of peripheral arterial disease (PAD) symptomology, however, the biological mechanisms remain unclear. The objective herein was to determine the impact of CKD on PAD pathology in mice. C57BL6/J mice were subjected to a diet-induced model of CKD by delivery of adenine for six weeks. CKD was confirmed by measurements of glomerular filtration rate, blood urea nitrogen, and kidney histopathology. Mice with CKD displayed lower muscle force production and greater ischemic lesions in the tibialis anterior muscle (78.1 ± 14.5% vs. 2.5 ± 0.5% in control mice, P < 0.0001, N = 5-10/group) and decreased myofiber size (1661 ± 134 μm2 vs. 2221 ± 100 μm2 in control mice, P < 0.01, N = 5-10/group). This skeletal myopathy occurred despite normal capillary density (516 ± 59 vs. 466 ± 45 capillaries/20x field of view) and limb perfusion. CKD mice displayed a ~50-65% reduction in muscle mitochondrial respiratory capacity in ischemic muscle, whereas control mice had normal mitochondrial function. Hydrogen peroxide emission was modestly higher in the ischemic muscle of CKD mice, which coincided with decreased oxidant buffering. Exposure of cultured myotubes to CKD serum resulted in myotube atrophy and elevated oxidative stress, which were attenuated by mitochondrial-targeted therapies. Taken together, these findings suggest that mitochondrial impairments caused by CKD contribute to the exacerbation of ischemic pathology.

Metabolomic and biochemical characterization of a new model of the transition of acute kidney injury to chronic kidney disease induced by folic acid

Background

Renal diseases represent a major public health problem. The demonstration that maladaptive repair of acute kidney injury (AKI) can lead to the development of chronic kidney disease (CKD) and end-stage renal disease has generated interest in studying the pathophysiological pathways involved. Animal models of AKI–CKD transition represent important tools to study this pathology. We hypothesized that the administration of multiple doses of folic acid (FA) would lead to a progressive loss of renal function that could be characterized through biochemical parameters, histological classification and nuclear magnetic resonance (NMR) profiling.

Methods

Wistar rats were divided into groups: the control group received a daily intraperitoneal (I.P.) injection of double-distilled water, the experimental group received a daily I.P. injection of FA (250 mg kg body weight⁻¹). Disease was classified according to blood urea nitrogen level: mild (40–80 mg dL⁻¹), moderate (100–200 mg dL⁻¹) and severe (>200 mg dL⁻¹). We analyzed through biochemical parameters, histological classification and NMR profiling.

Results

Biochemical markers, pro-inflammatory cytokines and kidney injury biomarkers differed significantly (P < 0.05) between control and experimental groups. Histology revealed that as damage progressed, the degree of tubular injury increased, and the inflammatory infiltrate was more evident. NMR metabolomics and chemometrics revealed differences in urinary metabolites associated with CKD progression. The main physiological pathways affected were those involved in energy production and amino-acid metabolism, together with organic osmolytes. These data suggest that multiple administrations of FA induce a reproducible model of the induction of CKD. This model could help to evaluate new strategies for nephroprotection that could be applied in the clinic.

Effect of chrysin on the formation of N-acetyl-p-benzoquinoneimine, a toxic metabolite of paracetamol in rats and isolated rat hepatocytes

Paracetamol (N-acetyl-para amino phenol) is the most commonly used analgesic and antipyretic around the world. Its causes hepatotoxicity and nephrotoxicity at overdose or even at therapeutic doses. It is primarily metabolized by glucuronidation and sulfate conjugation. It is also metabolized by cytochrome-P450 system (CYP2E1, CYP1A2 and CYP 3A4), leading to the formation of N-acetyl-p-benzoquinoneimine (NAPQI). The present study was planned to investigate the influence of chrysin (known CYP2E1 and CYP3A4 inhibitor) on the bioactivation of paracetamol to NAPQI using rat liver microsomes in vitro and rats in vivo. Paracetamol (80 mg/kg) was administered orally without or with silymarin (100 mg/kg), a known CYP2E1 inhibitor and chrysin (100 and 200 mg/kg) to rats for 15 consecutive days. The area under the plasma concentration-time curve (AUC_0-∞) and the peak plasma concentration (C_max) of paracetamol were dose-dependently increased with chrysin (100 and 200 mg/kg) compared to paracetamol control group. On the other hand, the AUC_0-∞ and C_max of NAPQI were decreased significantly with chrysin (100 and 200 mg/kg). The elevated liver and kidney function markers were significantly reduced by chrysin and silymarin compared to paracetamol control group (P < 0.01). Histopathological studies of liver and kidney also well correlated with liver and kidney function tests. Chrysin also reduced the formation of NAPQI in the incubation samples of rat hepatocytes. The present study (both in vivo and in vitro) results revealed that chrysin might be inhibited the CYP2E1, CYP1A2 and CYP3A4-mediated metabolism of paracetamol; thereby decreased the formation of NAPQI and protected the liver and kidney.

Dietary Chrysin Suppresses Formation of Actin Cytoskeleton and Focal Adhesion in AGE-Exposed Mesangial Cells and Diabetic Kidney: Role of Autophagy

Advanced glycation end products (AGE) play a causative role in the development of aberrant phenotypes of intraglomerular mesangial cells, contributing to acute/chronic glomerulonephritis. The aim of this study was to explore mechanistic effects of the flavonoid chrysin present in bee propolis and herbs on actin dynamics, focal adhesion, and the migration of AGE-exposed mesangial cells. The in vitro study cultured human mesangial cells exposed to 33 mM glucose and 100 μg/mL AGE-bovine serum albumin (AGE-BSA) for up to 5 days in the absence and presence of 1⁻20 μM chrysin. The in vivo study employed db/db mice orally administrated for 10 weeks with 10 mg/kg chrysin. The presence of ≥10 μM chrysin attenuated mesangial F-actin induction and bundle formation enhanced by AGE. Chrysin reduced the mesangial induction of α-smooth muscle actin (α-SMA) by glucose, and diminished the tissue α-SMA level in diabetic kidneys, indicating its blockade of mesangial proliferation. The treatment of chrysin inhibited the activation of vinculin and paxillin and the induction of cortactin, ARP2/3, fascin-1, and Ena/VASP-like protein in AGE-exposed mesangial cells. Oral administration of chrysin diminished tissue levels of cortactin and fascin-1 elevated in diabetic mouse kidneys. Mesangial cell motility was enhanced by AGE, which was markedly attenuated by adding chrysin to cells. On the other hand, chrysin dampened the induction of autophagy-related genes of beclin-1, LC3 I/II, Atg3, and Atg7 in mesangial cells exposed to AGE and in diabetic kidneys. Furthermore, chrysin reduced the mTOR activation in AGE-exposed mesangial cells and diabetic kidneys. The induction of mesangial F-actin, cortactin, and fascin-1 by AGE was deterred by the inhibition of autophagy and mTOR. Thus, chrysin may encumber diabetes-associated formation of actin bundling and focal adhesion and mesangial cell motility through disturbing autophagy and mTOR pathway.

Dietary polyphenols and their roles in fat browning

Discovery of the presence of brown adipose tissue (BAT) in newborn babies and adult humans, especially constitutively active brown fat or inducible beige fat, has led to the investigation of strategies employing BAT aimed at the development of novel therapeutic avenues for combating obesity and diabetes. Such antiobesity therapeutic tools include pharmaceutical and nutraceutical dietary polyphenols. Although there have been emerging notable advances in knowledge of and an increased amount of research related to brown and beige adipocyte developmental lineages and transcriptional regulators, current knowledge regarding whether and how food factors and environmental modifiers of BAT influence thermogenesis has not been extensively investigated. Therefore, in this review, we summarized recent updates on the exploration of dietary polyphenols while paying attention to the activation of BAT and thermogenesis. Specifically, we summarized findings pertaining to BAT metabolism, white adipose tissue (WAT) browning and thermogenic function of polyphenols (e.g., flavan-3-ols, green tea catechins, resveratrol, capsaicin/capsinoids, curcumin, thymol, chrysin, quercetin and berberine) that may foster a relatively safe and effective therapeutic option to improve metabolic health. We also deciphered the underlying proposed mechanisms through which these dietary polyphenols facilitate BAT activity and WAT browning. Characterization of thermogenic dietary factors may offer novel insight enabling revision of nutritional intervention strategies aimed at obesity and diabetes prevention and management. Moreover, identification of polyphenolic dietary factors among plant-derived natural compounds may provide information that facilitates nutritional intervention strategies against obesity, diabetes and metabolic syndrome.

Intermittent hypoxia exacerbates increased blood pressure in rats with chronic kidney disease

Kidney injury and sleep apnea (SA) are independent risk factors for hypertension. Exposing rats to intermittent hypoxia (IH) to simulate SA increases blood pressure whereas adenine feeding causes persistent kidney damage to model chronic kidney disease (CKD). We hypothesized that exposing CKD rats to IH would exacerbate the development of hypertension and renal failure. Male Sprague-Dawley rats were fed a 0.2% adenine diet or control diet (Control) until blood urea nitrogen was >120 mg/dl in adenine-fed rats (14 ± 4 days, mean ± SE). After 2 wk of recovery on normal chow, rats were exposed to IH (20 exposures/h of 5% O₂-5% CO₂ 7 h/day) or control conditions (Air) for 6 wk. Mean arterial pressure (MAP) was monitored with telemeters, and plasma and urine samples were collected weekly to calculate creatinine clearance as an index of glomerular filtration rate (GFR). Prior to IH, adenine-fed rats had higher blood pressure than rats on control diet. IH treatment increased MAP in both groups, and after 6 wk, MAP levels in the CKD/IH rats were greater than those in the CKD/Air and Control/IH rats. MAP levels in the Control/Air rats were lower than those in the other three groups. Kidney histology revealed crystalline deposits, tubule dilation, and interstitial fibrosis in both CKD groups. IH caused no additional kidney damage. Plasma creatinine was similarly increased in both CKD groups throughout whereas IH alone increased plasma creatinine. IH increases blood pressure further in CKD rats without augmenting declines in GFR but appears to impair GFR in healthy rats. We speculate that treating SA might decrease hypertension development in CKD patients and protect renal function in SA patients.

Adenine-induced chronic kidney disease in rats

Many animal models have been developed to study the causes and treatments of chronic kidney disease (CKD) in humans, an insidious disease resulting from kidney injury and characterized by persistent functional decline for more than 3 months, with or without evidence of structural deficit. The eventual outcome of CKD may be end-stage kidney disease (ESKD), where patients need dialysis or transplantation to survive. Cardiovascular disease is accelerated in patients with CKD and contributes to increased mortality, with the relationship between CKD and cardiovascular disease being bi-directional. Most animal models do not mimic the complexity of the human disease as many do not develop CKD-associated cardiovascular disease. The adenine diet model of CKD in rodents is an exception. The original adenine diet model produced rapid-onset kidney disease with extensive tubulointerstitial fibrosis, tubular atrophy, crystal formation and marked vessel calcification. Since then, lower adenine intake in rats has been found to induce slowly progressive kidney damage and cardiovascular disease. These chronic adenine diet models allow the characterization of relatively stable kidney and cardiovascular disease, similar to CKD in humans. In addition, interventions for reversal can be tested. Here the key features of the adenine diet model of CKD are noted, along with some limitations of other available models. In summary, the data presented here support the use of chronic low-dose adenine diet in rats as an easy and effective model for understanding human CKD, especially the links with cardiovascular disease, and developing potential therapeutic interventions.

Zhen-wu-tang ameliorates adenine-induced chronic renal failure in rats: regulation of the canonical Wnt4/beta-catenin signaling in the kidneys

ETHNOPHARMACOLOGICAL RELEVANCE

Zhen-wu-tang (ZWT), composed of Radix Aconiti lateralis, Rhizoma Atractylodis macrocephalae, Poria, Radix Paeoniae alba and ginger, is a classic Chinese herbal formula for the treatment of chronic kidney diseases that may cause chronic renal failure (CRF).

AIM OF THE STUDY

To better understand its clinical use, this study investigated the effects and underlying mechanisms of action of ZWT on CRF.

MATERIALS AND METHODS

CRF was induced by adenine. ZWT was given via an oral gavage method. The serum biochemical parameters were measured enzymatically or by ELISA. The kidneys were examined pathohistologically. The gene expression was analyzed by real time PCR and Western blot.

RESULTS

Similar to the positive control losartan, ZWT extract inhibited adenine-induced increase in serum concentrations of creatinine, BUN and advanced oxidation protein products in rats. These effects were accompanied by attenuation of proteinuria and renal pathological changes and suppression of renal mRNA and protein overexpression of Collagen IV and fibronectin, two of the key components of fibrosis. Mechanistically, renal mRNA and protein expression of Wnt4, a Wnt signaling ligand, was increased in the adenine-treated group, compared to the vehicle-treated control. Consistently, Wnt4 downstream genes beta-catenin and Axin were also overexpressed. Treatment with ZWT extract and losartan suppressed adenine-stimulated overexpression of these mRNAs and proteins.

CONCLUSIONS

The present results demonstrate that ZWT extract ameliorates adenine-induced CRF in rats by regulation of the canonical Wnt4/beta-catenin signaling in the kidneys. Our findings provide new insight into the underlying renoprotective mechanisms of the ancient formula.

Ameliorative effect of ursolic acid on renal fibrosis in adenine-induced chronic kidney disease in rats

Ursolic acid (UA), an ursane-type pentacyclic triterpenoid commonly found in apple peels and holy basil has been shown to possess many beneficial effects. Renal fibrosis is a complication of kidney injury and associated with increased risk of morbidity and mortality. In our previous investigation, a lupane-type pentacyclic triterpenoid, betulinic acid (BA) was found to have protective effect on chronic kidney disease (CKD) and renal fibrosis. This prompted us to explore the therapeutic value of UA, a chemically related compound to BA in CKD. CKD was induced by feeding adenine with the feed at a concentration of 0.75% for 28 days. UA at the dose rate of 30 mg/kg in 0.5% carboxy methyl cellulose (CMC) was administered by oral route, simultaneously with adenine feeding for 28 days. Adenine feeding increased the kidney weight to body weight index, decreased the kidney function due to injury as indicated by increased markers like serum urea, uric acid, creatinine, cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) and initiated the fibrotic response in kidney by increasing the profibrotic proteins viz. transforming growth factor-beta (TGF-β), connective tissue growth factor (CTGF), fibronectin and collagen. However, treatment with UA reversed the damage induced by adenine as shown by reduced kidney injury and fibrosis markers which was further clearly evident in histological picture indicating the suitability of UA for use in CKD.

The role of molecular modelling strategies in validating the effects of chrysin on sodium arsenite-induced chromosomal and DNA damage

Chrysin (CHR) is a food-based bioactive ingredient whereas, sodium arsenite (SA) is one of the major contaminant in drinking water. When ingested, SA contributes to tissue damage due to bioactivation by S-adenosyl methionine (SAM)-dependent methyltransferase. Hence, the needs to nullify this effect by investigating the potentials of CHR on SA-induced genotoxicity in rats. The experiment was divided into two successive stages (ameliorative and preventive, curative studies) for 1 week. Rats were divided into four groups: distilled water, 10mg/kg SA, 10mg/kg CHR and co-administration. In stage 2, the experimental groups were given either CHR or SA for 1 week, and treated in reversed order for additional week. Lipid peroxidation, protein carbonyl and DNA fragmentation in liver, blood brain and bone marrow cells micronucleus were assayed for using standard protocols. Molecular docking of SAM-dependent methyltransferase in the presence of CHR was conducted. CHR significantly ( p < 0.05) decreased the level of lipid peroxidation, protein carbonyls and DNA fragmentation in blood, liver and brain tissues as against group treated with SA. It also significantly ( p<0.05) reduced the level of micronuclei generated in bone marrow cells. The effects of CHR were shown to be ameliorative, preventive and curative in nature. Furthermore, CHR was able to dock (with binding energy of −24.81 kcal/mol and predicted inhibition kinetic constant (Ki) of 0.959 µM) into the active site of SAM-dependent methyltransferase with strong hydrogen bond and hydrophobic interactions. The study might have unravelled the potentials of CHR against SA-induced chromosomal and DNA damage, which might be due to inhibition of SAM-dependent methyltransferase.

Chrysin ameliorates podocyte injury and slit diaphragm protein loss via inhibition of the PERK-eIF2α-ATF-CHOP pathway in diabetic mice

Glomerular epithelial podocytes are highly specialized cells that play a crucial role in maintaining normal function of the glomerular filtration barrier via their foot processes. Chrysin (5,7-dihydroxyflavone) is a natural flavonoid found in propolis and mushrooms that has anti-inflammatory, antioxidant and anticancer properties. This study aimed to evaluate the renoprotective effects of chrysin on podocyte apoptotic loss and slit diaphragm protein deficiency in high glucose-exposed podocytes and in db/db mouse kidneys. Exposure to high glucose (33 mmol/L) caused glomerular podocyte apoptosis in vitro, which was dose-dependently attenuated by nontoxic chrysin (1-20 μmol/L) through reduction of DNA fragmentation. Chrysin treatment dose-dependently restored the increased Bax/Bcl-2 ratio, and suppressed Apaf-1 induction and the elevated cytochrome c release in high glucose-exposed renal podocytes. In diabetic db/db mice, oral administration of chrysin (10 mg·kg^-1·d^-1, for 10 weeks) significantly attenuated proteinuria, and alleviated the abnormal alterations in glomerular ultrastructure, characterized by apoptotic podocytes and foot process effacement. In addition, this compound improved the induction of slit diaphragm proteins podocin/nephrin in the diabetic glomeruli. Exposure to high glucose elevated the unfolded protein response (UPR) to ER stress in renal podocytes, evidenced by up-regulation of PERK-eIF2α-ATF4-CHOP. Chrysin treatment blocked such ER stress responses pertinent to podocyte apoptosis and reduced synthesis of slit diaphragm proteins in vitro and in vivo. These observations demonstrate that targeting ER stress is an underlying mechanism of chrysin-mediated amelioration of diabetes-associated podocyte injury and dysfunction.

Protective Effects of Chrysin Against Drugs and Toxic Agents

Issues:

Polyphenolic compounds, especially flavonoids, are known as the most common chemical class of phytochemicals, which possess a multiple range of health-promoting effects. Flavonoids are ubiquitous in nature. They are also present in food, providing an essential link between diet and prevention of several diseases.

Approach:

Chrysin (CH), a natural flavonoid, was commonly found in propolis and honey and traditionally used in herbal medicine. A growing body of scientific evidence has shown that CH possesses protective effects against toxic agents in various animal tissues, including brain, heart, liver, kidney, and lung.

Key Findings:

This study found that CH may be effective in disease management induced by toxic agents. However, due to the lack of information on human, further studies are needed to determine the efficacy of CH as an antidote agent in human.

Conclusion:

The present article aimed to critically review the available literature data regarding the protective effects of CH against toxic agent–induced toxicities as well as its possible mechanisms.

Effect of aqueous extract and anthocyanins of calyces of Hibiscus sabdariffa (Malvaceae) in rats with adenine-induced chronic kidney disease

OBJECTIVES

The aim of this work was to assess the possible beneficial effects of aqueous extracts of Hibiscus sabdariffa L. calyces and anthocyanins isolated therefrom in an adenine-induced chronic kidney disease (CKD) model.

METHODS

Rats were orally given, for 28 consecutive days, either adenine alone or together with either aqueous extract of H. sabdariffa calyces (5 and 10%) or anthocyanins (50, 100 and 200 mg/kg of anthocyanin concentrate). For comparative purposes, two groups of rats were given lisinopril (10 mg/kg).

KEY FINDINGS

When either H. sabdariffa aqueous extract or the anthocyanins isolated from it was administered along with adenine, the adverse effects of adenine-induced CKD were significantly lessened, mostly in a dose-dependent manner. The positive effects were similar to those obtained by administration of lisinopril.

CONCLUSIONS

The results obtained show that both H. sabdariffa and its anthocyanins could be considered as possible promising safe dietary agents that could be used to attenuate the progression of human CKD. This could have added significance as H. sabdariffa tea is widely consumed in many parts of Africa and Asia and is thus readily available.

Hydrogen sulfide ameliorates chronic renal failure in rats by inhibiting apoptosis and inflammation through ROS/MAPK and NF-κB signaling pathways

Chronic renal failure (CRF) is a major public health problem worldwide. Hydrogen sulfide (H₂S) plays important roles in renal physiological and pathophysiological processes. However, whether H₂S could protect against CRF in rats remains unclear. In this study, we found that H₂S alleviated gentamicin-induced nephrotoxicity by reducing reactive oxygen species (ROS)-mediated apoptosis in normal rat kidney-52E cells. We demonstrated that H₂S significantly improved the kidney structure and function of CRF rats. We found that H₂S decreased the protein levels of Bax, Caspase-3, and Cleaved-caspase-3, but increased the expression of Bcl-2. Treatment with H₂S reduced the levels of malondialdehyde and ROS and increased the activities of superoxide dismutase and glutathione peroxidase. H₂S significantly abolished the phosphorylation of extracellular signal-regulated protein kinase 1/2, c-Jun N-terminal kinase, and p38 in the kidney of CRF rats. Furthermore, H₂S decreased the expression levels of tumor necrosis factor-α, interleukin (IL)-6, IL-10, and monocyte chemoattractant protein-1, as well as the protein levels of p50, p65, and p-p65 in the kidney of CRF rats. In conclusion, H₂S could ameliorate adenine-induced CRF in rats by inhibiting apoptosis and inflammation through ROS/mitogen-activated protein kinase and nuclear factor-kappa B signaling pathways.

The molecular mechanisms of hemodialysis vascular access failure

The arteriovenous fistula has been used for more than 50 years to provide vascular access for patients undergoing hemodialysis. More than 1.5 million patients worldwide have end stage renal disease and this population will continue to grow. The arteriovenous fistula is the preferred vascular access for patients, but its patency rate at 1 year is only 60%. The majority of arteriovenous fistulas fail because of intimal hyperplasia. In recent years, there have been many studies investigating the molecular mechanisms responsible for intimal hyperplasia and subsequent thrombosis. These studies have identified common pathways including inflammation, uremia, hypoxia, sheer stress, and increased thrombogenicity. These cellular mechanisms lead to increased proliferation, migration, and eventually stenosis. These pathways work synergistically through shared molecular messengers. In this review, we will examine the literature concerning the molecular basis of hemodialysis vascular access malfunction.

The Biology of Hemodialysis Vascular Access Failure

Arteriovenous fistulas (AVFs) are essential for patients and clinicians faced with end-stage renal disease (ESRD). While this method of vascular access for hemodialysis is preferred to others due to its reduced rate of infection and complications, they are plagued by intimal hyperplasia. The pathogenesis of intimal hyperplasia and subsequent thrombosis is brought on by uremia, hypoxia, and shear stress. These forces upregulate inflammatory and proliferative cytokines acting on leukocytes, fibroblasts, smooth muscle cells, and platelets. This activation begins initially with the progression of uremia, which induces platelet dysfunction and primes the body for an inflammatory response. The vasculature subsequently undergoes changes in oxygenation and shear stress during AVF creation. This propagates a strong inflammatory response in the vessel leading to cellular proliferation. This combined response is then further subjected to the stressors of cannulation and dialysis, eventually leading to stenosis and thrombosis. This review aims to help interventional radiologists understand the biological changes and pathogenesis of access failure.

Chrysin induces brown fat-like phenotype and enhances lipid metabolism in 3T3-L1 adipocytes

OBJECTIVES

Many studies have to do with promising therapeutic phytochemicals such as flavonoids to treat obesity and related complications, and a number of dietary compounds have been proposed as tools for increasing energy expenditure and decreasing fat accumulation in mammals. Here, we show that the flavonoid chrysin induces browning of 3T3-L1 adipocytes via enhanced expression of brown fat-specific genes and proteins as well as enhances lipid metabolism.

METHODS

Chrysin-induced fat browning was investigated by determining expression levels of brown fat-specific genes and proteins by real-time polymerase chain reaction and immunoblot analysis, respectively.

RESULTS

Chrysin enhanced expression of brown fat-specific markers and increased protein levels of peroxisome proliferator-activated receptor (PPAR)α, PPARγ, PPARδ, phosphorylated AMP-activated protein kinase (p-AMPK), phosphorylated acetyl-CoA carboxylase, hormone sensitive lipase, perilipin, carnitine palmitoyltransferase 1, acyl-coenzyme A oxidase 1, peroxisome proliferator-activated receptor-1 alpha (PGC-1α), and uncoupling protein 1 (UCP-1), suggesting its possible role in augmentation of lipolysis, fat oxidation, and thermogenesis as well as reduction of lipogenesis. Increased expression of UCP-1 and other brown fat-specific markers was possibly mediated by chrysin-induced activation of AMPK based on the fact that inhibition of AMPK by dorsomorphin abolished expression of PR domain-containing 16, UCP-1, and PGC-1α while the activator 5-aminoimidazole-4-carboxamide ribonucleotide elevated expression of these brown marker proteins.

CONCLUSION

Our findings suggest that chrysin plays a dual modulatory role in the form of inducing the brown-like phenotype as well as enhancing lipid metabolism and thus may be explored as a potentially promising food additive for prevention of obesity.

Renoprotective effects of aliskiren on adenine-induced tubulointerstitial nephropathy: possible underlying mechanisms

The present study investigated the possible renoprotective effect of direct renin inhibitor (aliskiren) on renal dysfunctions, as well as its underlying mechanisms in rat model of adenine-induced tubulointerstitial nephropathy. Forty male Sprague-Dawley rats were randomized into 4 groups; normal group, aliskiren group (normal rats received 10 mg/kg aliskiren), adenine group (animals received high-adenine diet for 4 weeks and saline for 12 weeks), and adenine + aliskiren group (animals received adenine for 4 weeks and aliskiren 10 mg/kg for 12 weeks). It was found that adenine caused significant decrease in body mass, Hb, HR, serum Ca(2+), eNOS and nrf2 expression, GSH, and catalase in kidney tissues with significant increase in arterial blood pressure (ABP), serum creatinine, BUN, plasma renin activity (PRA), K(+) and P, urinary albumin excretion (UAE), caspase-3, and MDA (lipid peroxidation marker) in kidney tissues compared to normal group (p < 0.05). Administration of aliskiren caused significant improvement in all studied parameters compared to adenine group (p < 0.05). We concluded that aliskiren has renoprotective effect against adenine-induced nephropathy. This might be due to inhibition of PRA, attenuation of oxidative stress, activation of Nrf2 and eNOS genes, and suppression of caspase-3.