Lipoic acid ameliorates oxidative stress and renal injury in alloxan diabetic rabbits

Reduction in Glomerular and Renal Tubular Damage in Kidneys of Diabetic Rats Supplemented with Alpha-Lipoic Acid

Chronic hyperglycemia caused by diabetes results in systemic damage to the body, and the kidney ends up being the target of tissue damage. The use of antioxidants such as alpha-lipoic acid (ALA) has been shown to improve clinical and biochemical parameters in diabetic patients as they help in the prevention of oxidative stress. The present study aimed to undertake a comparative evaluation of the renal morphology of normal and diabetes-induced Wistar rats supplemented with ALA. The experiment had 4 experimental groups (n=7): a control group and a diabetic group that were fed commercial food; an alpha-lipoic group and an alpha-lipoic diabetic group that received the ALA supplement. Diabetes was induced with a single intraperitoneal injection of alloxane monohydrate administered after fasting. After 60 days of the experiment, the kidneys were excised to study the histomorphometric and stereological parameters of the glomeruli and renal tubules and the immunohistochemical parameters with a podocyte count. In the evaluation, the ALA promoted improvement in all of the relevant parameters of the glomerular areas and attenuation of tubular lesions of diabetic animals (p<0.001). Supplementation with ALA also showed beneficial effects in diabetic animals, such as reducing hyperglycemia and the damage promoted by oxidative stress alongside promoting a protective effect on the renal parenchyma. The reduction of glomerular and tubular damage delayed the advance of diabetic nephropathy and its complications, preventing renal failure in diabetic groups.

Effects of Alpha-lipoic Acid Supplementation on Human Diabetic Nephropathy: A Systematic Review and Meta-analysis

BACKGROUND

Diabetic nephropathy (DN) is kidney dysfunction, which occurs due to elevated urine albumin excretion rate and reduced glomerular filtration rate. Studies on animals have shown that alpha-lipoic acid (ALA) supplementation can reduce the development of DN.

OBJECTIVES

We performed a systematic review and meta-analysis to examine the effects of ALA supplementation on biological indices (albumin, creatinine, etc.) indicative of human DN.

METHODS

The search procedure included PubMed Central, Embase, Cochrane Library (trials), and Web of Science (protocol registration: INPLASY202060095).

RESULTS

We found that ALA supplementation decreased 24h urine albumin excretion rate in patients with diabetes (standardized mean difference=-2.27; confidence interval (CI)=(-4.09)-(-0.45); I²=98%; Z=2.44; p=0.01). A subgroup analysis revealed that the results of studies examining only ALA did not differ from those examined ALA in combination with additional medicines (Chisquared= 0.19; p=0.66; I²=0%), while neither ALA nor ALA plus medication had an effect on 24h urine albumin excretion rate (p>0.05). Also, ALA supplementation decreased urine albumin mg/l (mean difference (MD)=-12.95; CI=(-23.88)-(-2.02); I²=44%; Z=2.32; p=0.02) and urine albumin to creatinine ratio (MD=-26.96; CI=(-35.25)-(-18.67); I²=0%; Z=6.37; p<0.01) in patients with diabetes. When the studies examining ALA plus medication were excluded, it was found that ALA supplementation had no effect on urine albumin mg/l (p>0.05) but did significantly decrease urine albumin to creatinine ratio (MD=-25.88, CI=(34.40-(-17.36), I²=0%, Z=5.95, p<0.00001).

CONCLUSION

The available evidence suggests that ALA supplementation does not improve biological indices that reflect DN in humans. Overall, we identified limited evidence, and therefore, the outcomes should be considered with caution.

Long-Term Alpha-Lipoic Acid (ALA) Antioxidant Therapy Reduces Damage in the Cardiovascular System of Streptozotocin-Induced Diabetic Rats

Cellular damage, lipid oxidation and the action of inflammatory cytokines are implicated in the evolution of vascular complications associated with diabetes mellitus (DM) hyperglycemia. In contrast, alpha-lipoic acid (ALA) is a supplement with antioxidant and anti-inflammatory effects. This study aims to evaluate the overall effects of ALA supplementation by assessing its long-term systemic action on the vascular morphology of rats with induced diabetes. A total of 28 male rats were divided into 4 groups with seven animals each. For diabetes induction, two groups received streptozotocin. The animals in the lipoic and diabetic lipoic groups received ALA supplement. After 8 weeks the animals were anesthetized and blood collected was for hematological, biochemical and serological analyses. The thoracic aorta was removed, processed for paraffin and histological sections were stained for morphometric analysis. In diabetic groups, an improvement in hematological profile was observed, with platelet reduction in the diabetic lipoic group. ALA addition to the diet attenuated the negative effects in lipid profile; moreover, renal, hepatic and inflammatory parameters reduced or displayed values close to the values of the normal control. The anti-inflammatory effect of ALA was observed in diabetic animals, with a reduction of inflammatory citokines, accompanied by the improvement of morphological parameters in the aorta. In conclusion, long-term supplementation with ALA promoted systemic improvement, thus reducing the risk of vascular diseases. The changes in the renal and hepatic parameters without any negative impact in the hematological profile also show that ALA can be indicated as a low-risk prophylaxis or complementary therapy.

Effects of valsartan combined with α-lipoic acid on renal function in patients with diabetic nephropathy: a systematic review and meta-analysis

BACKGROUND

Diabetic nephropathy (DN) is one of the most serious microvascular complications of diabetes, valsartan and α-lipoic acid alone or in combination has been used for the treatment of patients with DN. However, some results in these clinical reports were still controversial. The purpose of this study was to evaluate the efficacy of valsartan combined with α-lipoic acid on renal function in patients with DN.

METHODS

We searched the electronic databases including PubMed, Sciencedirect, EMBASE, Cochrane library, Chinese national knowledge infrastructure (CNKI) and Wanfang databases, and the publication deadline was limited to January 2020. Randomized controlled trials (RCTs) evaluating the effects of valsartan combined with α-lipoic acid in DN patients were included. Pooled estimates were conducted using a fixed or random effect model. The outcomes included urinary albumin excretion rate (UAER), and the level of urinary albumin, β₂-microglobulin (β₂-MG), hypersensitive C-reactive protein (hs-CRP) and oxidative stress.

RESULTS

11 studies with 1294 participants were included in this study. The pooled analysis indicated that α-lipoic acid combined with valsartan could remarkably reduce UAER (P < 0.00001, SMD = -1.95, 95%CI = -2.55 to - 1.20; P = 0.03, SMD = -0.85, 95%CI = -1.59 to - 0.1) and the level of urinary albumin (P = 0.001, SMD = -1.48, 95%CI = - 2.38 to - 0.58; P = 0.01, SMD = -1.67, 95%CI = -3.00 to - 0.33), β₂-MG (P < 0.001,SMD = - 2.59, 95%CI = -3.78 to - 1.40; P = 0.03, SMD = -0.48, 95%CI = -0.93 to - 0.04) when compared with valsartan or lipoic acid monotherapy in patients with DN. However, there was no significant difference in the level of hs-CRP among the three therapies (P = 0.06, SMD = -2.80, 95%CI = -5.67 to 0.07; P = 0.10, SMD = -0.42, 95%CI = - 0.92 to 0.08). In addition, α-lipoic acid combined with valsartan markedly increased the level of SOD (P = 0.03, SMD = 1.24, 95%CI = 0.32 to 1.03; P = 0.0002, SMD = 0.68, 95%CI = 0.32 to 1.03) and T-AOC (P < 0.00001, SMD = 0.89, 95%CI = 0.62 to 1.16; P = 0.02, SMD = 0.58, 95%CI = 0.10 to1.07), and reduced the level of MDA(P = 0.0002, SMD = -1.99, 95%CI = -3.02 to - 0.96; P = 0.0001, SMD = -0.69, 95%CI = -1.04 to - 0.34).

CONCLUSIONS

α-lipoic acid combined with valsartan could significantly reduce the level of urinary albumin and oxidative stress, increase antioxidant capacity and alleviate renal function damage in patients with DN, and this will provide a reference for the selection of treatment drugs for DN.

Protective effects of alpha-lipoic acid on hair cell damage in diabetic zebrafish model

Hearing impairment is one of the complications in diabetes mellitus; however, there are very few therapeutic studies on it. In this study, we investigated the protective effect of alpha-lipoic acid (ALA) on hearing loss in diabetic transgenic zebrafish and confirmed that ALA protects the loss of hair cells (HCs) caused by hyperglycemia. The data indicated that ALA has a protective effect on the damage to HCs in diabetic zebrafish.

Hallmarks of oxidative stress in the livers of aged mice with mild glycogen branching enzyme deficiency

Glycogen branching enzyme (GBE1) introduces branching points in the glycogen molecule during its synthesis. Pathogenic GBE1 gene mutations lead to glycogen storage disease type IV (GSD IV), which is characterized by excessive intracellular accumulation of abnormal, poorly branched glycogen in affected tissues and organs, mostly in the liver. Using heterozygous Gbe1 knock-out mice (Gbe1^+/-), we analyzed the effects of moderate GBE1 deficiency on oxidative stress in the liver. The livers of aged Gbe1^+/- mice (22 months old) had decreased GBE1 protein levels, which caused a mild decrease in the degree of glycogen branching, but did not affect the tissue glycogen content. GBE1 deficiency was accompanied by increased protein carbonylation and elevated oxidation of the glutathione pool, indicating the existence of oxidative stress. Furthermore, we have observed increased levels of glutathione peroxidase and decreased activity of respiratory complex I in Gbe1^+/- livers. Our data indicate that even mild changes in the degree of glycogen branching, which did not lead to excessive glycogen accumulation, may have broader effects on cellular bioenergetics and redox homeostasis. In young animals cellular homeostatic mechanisms are able to counteract those changes, while in aged tissues the changes may lead to increased oxidative stress.

ALA protects against ERS-mediated apoptosis in a cochlear cell model with low citrate synthase expression

A/J mouse is a model of age-related hearing loss (AHL). Mutation in the citrate synthase (Cs) gene of the mouse plays an important role in the hearing loss and degeneration of cochlear cells. To investigate the pathogenesis of cochlear cell damage in A/J mice resulted from Cs mutation, we downregulated the expression level of CS in HEI-OC1, a cell line of mouse cochlea, by shRNA. The results showed that low CS expression led to low ability of cell proliferation. Further study revealed an increase level of reactive oxygen species (ROS), activation of ATF6 mediated endoplasmic reticulum stress (ERS) and high expression levels of caspase12 and Bax in the cells. Moreover, the AEBSF, an ATF6 inhibitor, could reduce the expression levels of caspase-12 and Bax by inhibiting the hydrolysis of ATF6 in the cells. Finally, antioxidant alpha-lipoic acid (ALA) reduced the ROS levels and the apoptotic signals in the cell model with low CS expression. We therefore conclude that the ERS mediated apoptosis, which is triggered by ROS, may be involved in the cell degeneration in the cochleae of A/J mice.

Effects of the Combination of β-Hydroxy-β-Methyl Butyrate and R(+) Lipoic Acid in a Cellular Model of Sarcopenia

: Sarcopenia is a clinical problem associated with several pathological and non-pathological conditions. The aim of the present research is the evaluation of the pharmacological profile of the leucine metabolite β-hydroxy-β-methyl butyrate (HMB) associated with the natural R(+) stereoisomer of lipoic acid (R(+)LA) in a cellular model of muscle wasting. The C2C12 cell line is used as myoblasts or is differentiated in myotubes, sarcopenia is induced by dexamethasone (DEX). A Bonferroni significant difference procedure is used for a post hoc comparison. DEX toxicity (0.01-300 µM concentration range) is evaluated in myoblasts to measure cell viability and caspase 3 activation after 24 h and 48 h; cell incubation with 1 µM DEX for 48 h is chosen as optimal treatment for decreasing cell viability and increasing caspase 3 activity. R(+)LA or HMB significantly prevents DEX-induced cell mortality; the efficacy is improved when 100 µM R(+)LA is combined with 1 mM HMB. Regarding myoblasts, this combination significantly reduces DEX-evoked O2- production and protein oxidative damage. During the early phase of myotube formation, the mixture preserves the number of myogenin-positive cells, whereas it completely prevents the DEX-dependent damage in a later phase of myotube differentiation (7 days), as evaluated by cell diameter and percentage of multinucleated cells. R(+)LA in association with HMB is suggested for sarcopenia therapy.

Otoprotective Effects of α-lipoic Acid on A/J Mice With Age-related Hearing Loss

OBJECTIVE

A/J mice are a mouse model of age-related hearing loss (AHL) with progressive degeneration of outer hair cells (OHCs), spiral ganglion neurons (SGNs), and stria vascularis. This study was carried out to observe the otoprotective effects of α-lipoic acid on A/J mice.

METHODS

A/J mouse pups at postnatal day 7 were randomly distributed into the untreated group, the dimethyl sulfoxide (DMSO) group, and the α-lipoic acid + DMSO group. α-lipoic acid was given to the mice intraperitoneally at a dosage of 50 μg/g body weight every other day. Time course auditory-evoked brainstem response (ABR) thresholds were tested. OHC loss was counted and the densities of SGNs and the width of stria vascularis were measured at 4 and 8 weeks of age.

RESULTS

Measurement of the ABR thresholds revealed that hearing loss in A/J mice was attenuated by α-lipoic acid at age from 3 to 8 weeks. Moreover, preservation effects of OHCs, SGNs, and stria vascularis by α-lipoic acid were observed in the cochleae of A/J mice at 4 and 8 weeks of age.

CONCLUSION

Hearing loss in A/J mice can be attenuated by α-lipoic acid. The otoprotective effects of α-lipoic acid on A/J mice may be obtained by preserving OHCs, SGNs, and stria vascularis in the cochleae. The oxidative damage related to gene mutations may be a potential target for AHL prevention and therapy.

Therapeutic Effects of the Combination of Alpha-Lipoic Acid (ALA) and Coenzyme Q10 (CoQ10) on Cisplatin-Induced Nephrotoxicity

Background

Nephrotoxicity of cisplatin has been recognized since its introduction more than 25 years ago. However, despite intense efforts to develop less toxic and equally effective alternatives, cisplatin continues to be widely prescribed. Aim and Objectives. The study is aimed at assessing the possible prophylactic effect of coenzyme Q10 (CoQ10) and alpha-lipoic acid (ALA) (separately or in combination) on experimentally cisplatin-induced nephrotoxicity. Subjects and Methods. An experimental study was performed on adult male albino rats (n = 40), weighing 200–250 g. Rats were randomly divided into 5 groups: group I (normal saline control), group II (cisplatin control), group III (CoQ10 and cisplatin), group IV (ALA and cisplatin), and group V (CoQ10, ALA, and cisplatin). CoQ10 and/or ALA were given as pretreatment for 9 days, followed by cisplatin injection in the 10th day of the study, followed by a short posttreatment course for 3 days. Renal functions, tissue antioxidant activity, and inflammatory markers (tumor necrosis factor, TNF) were estimated along with histopathological study.

Results

Renal function tests and urinary proteins were significantly higher within group II compared with other groups (P value <0.001). Creatinine clearance was significantly higher with combination therapy (group V compared to other groups). Both TNF and malondialdehyde (MDA) were significantly higher within group II whereas GSH content, catalase, and superoxide dismutase (SOD) were significantly lower in group II. MDA level was significantly lower when combination therapy was used. Marked renal damage was histologically detected in the cisplatin group, whereas the least renal damage was noticed in the combination group.

Conclusion

The study confirmed the role of antioxidants in preventing nephrotoxicity caused by cisplatin; the prophylactic effect of combined therapy with CoQ10 and ALA is superior to that of monotherapy.

Morphofunctional condition of the pancreatic insular apparatus in old rats with alloxan-induced diabetes and its correction with lipoic acid

The concentration of glucose and glycosylated hemoglobin in the blood of animals increases as a result of physiological aging. This is due to damage to the pancreatic insular apparatus and a decrease in the number and functioning of active β-cells. The development of alloxan-induced diabetes in old rats is characterized by a decrease in the number of islets of Langerhans, an enlargement of the preserved islets, and a sharp decrease in the number of active endocrine cells. The injection of lipoic acid partially corrected the morphofunctional condition of the islets of Langerhans and the biochemical values of the animals’ peripheral blood.

Synthesis and Photodynamic Activity of Vitamin-Chlorin Conjugates at Nanomolar Concentrations against Prostate Cancer Cells

Phototoxicity response of synthesized vitamin-chlorin conjugates and their zinc and indium complexes was determined in the human PC-3 prostate cancer cell line, which was previously demonstrated to overexpress vitamin receptors on the cell surface. Pantothenic acid (Vit B5) and lipoic acid (or thioctic acid) were covalently linked to methyl pheophorbide (a chlorophyll derivative) and subsequently metallated with zinc and indium. Cell survival assay indicated that the vitamin-chlorin conjugates have better photodynamic activity against the PC-3 prostate cancer line at the nanomolar concentration range than the commercially available starting precursor methyl pheophorbide. Fluorescence and transmission electron microscopy studies indicated some formation of apoptotic cells and cytoplasmic vacuoles of photosensitized prostatic cells. Targeting vitamin receptors in prostatic cancer cells can be utilized to enhance specificity of photosensitizers for photodynamic therapy applications.

Biochemical and clinical relevance of alpha lipoic acid: antioxidant and anti-inflammatory activity, molecular pathways and therapeutic potential

BACKGROUND

The molecular nature of lipoic acid (LA) clarifies its capability of taking part to a variety of biochemical reactions where redox state is meaningful. The pivotal action of LA is the antioxidant activity due to its ability to scavenge and inactivate free radicals. Furthermore, LA has been shown to chelate toxic metals both directly and indirectly by its capability to enhance intracellular glutathione (GSH) levels. This last property is due to its ability to interact with GSH and recycle endogenous GSH. LA exhibits significant antioxidant activity protecting against oxidative damage in several diseases, including neurodegenerative disorders. Interestingly, LA is unique among natural antioxidants for its capability to satisfy a lot of requirements, making it a potentially highly effective therapeutic agent for many conditions related with oxidative damage. In particular, there are evidences showing that LA has therapeutic activity in lowering glucose levels in diabetic conditions. Similarly, LA supplementation has multiple beneficial effects on the regression of the mitochondrial function and on oxidative stress associated with several diseases and aging.

AIM

The aim of the present review is to describe the molecular mechanisms underlying the beneficial effects of LA under various experimental conditions and disease and how to exploit such effect for clinical purposes.

CONCLUSION

LA has pleiotropic effects in different pathways related with several diseases, its use as a potential therapeutic agent is very promising.

Twenty years after ACEIs and ARBs: emerging treatment strategies for diabetic nephropathy

Diabetic nephropathy (DN) is a serious complication of both type 1 and type 2 diabetes mellitus. The disease is now the most common cause of end-stage kidney disease (ESKD) in developed countries, and both the incidence and prevalence of diabetes mellitus is increasing worldwide. Current treatments are directed at controlling hyperglycemia and hypertension, as well as blockade of the renin angiotensin system with angiotensin-converting enzyme inhibitors (ACEIs), and angiotensin receptor blockers. Despite these therapies, DN progresses to ESKD in many patients. As a result, much interest is focused on developing new therapies. It has been over two decades since ACEIs were shown to have beneficial effects in DN independent of their blood pressure-lowering actions. Since that time, our understanding of disease mechanisms in DN has evolved. In this review, we summarize major cell signaling pathways implicated in the pathogenesis of diabetic kidney disease, as well as emerging treatment strategies. The goal is to identify promising targets that might be translated into therapies for the treatment of patients with diabetic kidney disease.

Leukemia Inhibitory Factor and Fibroblast Growth Factor 2 Critically and Mutually Sustain Pluripotency of Rabbit Embryonic Stem Cells

Effects of leukemia inhibitory factor (LIF) and fibroblast growth factor 2 (FGF2) on establishment and maintenance of rabbit embryonic stem cell (rESC) lines were assessed. When grown on MEF feeders, rESC lines derived from fertilized embryos were established and maintained in medium containing paracrine factors LIF (via STAT3) and/or FGF2 (via MEK-ERK1/2 and PI3K-AKT). However, high levels of ERK1/2 and AKT activities in rESCs were crucial for maintaining their undifferentiated proliferation. Although rESCs under the influence of either LIF (500, 1,000, and 2,000 U/ml) or FGF2 (5, 10, and 20 ng/ml) alone had enhanced expression of pluripotency markers, peak expression occurred when both LIF (1,000 U/ml) and FGF2 (10 ng/ml) were applied. Induced dephosphorylation of STAT3, ERK1/2, and AKT by specific inhibitors limited growth of rESCs and caused remarkable losses of self-renewal capacity; therefore, we inferred that STAT3, ERK, and AKT had essential roles in maintaining rESC proliferation and self-renewal. We concluded that LIF and FGF2 jointly maintained the undifferentiated state and self-renewal of rESCs through an integrative signaling module.

Alleviation of podocyte injury: the possible pathway implicated in anti-inflammation of alpha-lipoic acid in type 2 diabetics

BACKGROUND AND AIMS

The objective of this study is to observe the effect of alpha-lipoic acid (ALA) on Pod injury by anti-inflammation and explore its possible renal protective mechanism.

METHODS

A total of 36 cases with type 2 diabetes with microalbuminuria and fasting plasma glucose (FPG) levels less than 9 mmol/L and glycated hemoglobin A1c (HbA1c) ≤9.0 % were recruited to be treated with ALA (600 mg, daily) for 6 months (group DA). Another 30 healthy individuals were chosen as normal controls (group NC). The levels of serum creatinine (Cr), FPG, and HbA1c were detected; blood pressure was recorded; and early morning urine samples (corrected for urinary Cr) were collected for the examination of urinary monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-β1 (TGF-β1), podocalyxin (PCX), nephrin, albumin and Cr in group NC and group DA at the baseline and the sixth month.

RESULTS

The excretions of urinary MCP-1, TGF-β1, PCX, nephrin and albumin to Cr ratio (abbreviated as UMCR, UTCR, UPCR, UNCR and UACR respectively) were significantly increased in group DA compared with group NC (all P < 0.01), and after 6-month treatment, all indexes mentioned above decreased markedly (P < 0.05), while FPG and HbA1c had no obvious changes. Additionally, there was a positive correlation between UMCR, UTCR with UPCR, UNCR and UACR, respectively (all P < 0.01).

CONCLUSIONS

Anti-inflammation of ALA in vivo and local kidney is implicated in the protection of glomerular Pod injury in patients with type 2 diabetes.

Oxidative hepatotoxicity effects of monocrotaline and its amelioration by lipoic acid, S-adenosyl methionine and vitamin E

Liver is the major site for several xenobiotics metabolism, and formation of toxic metabolites that may be hepatotoxic, therefore the burden of metabolism and exposure to dangerous chemicals make liver vulnerable to a variety of disorders. Our work aimed to investigate the effects of some antioxidants such as lipoic acid (LA), S-adenosyl methionine (SAM) and vitamin E in a trail to investigate the possibility of using these substances to relieve and protect liver from exposure to monocrotaline (MCT). Twenty-five mature adult rats were classified into five groups (five rats in each group), control group, MCT-induced hepatic damage, LA+MCT, SAM+MCT and vitamin E+MCT group. Homogenates of liver samples were used for measuring the oxidative biomarkers and hepatic antioxidant status. The results showed that administration of vitamin E, SAM and LA caused a significant increase in liver glutathione contents, glutathione reductase, glutathione peroxidase and glutathione-S-transferase activities and a significant decrease in hepatic catalase and superoxide dismutase. We could conclude that administration of natural LA, SAM and vitamin E before and after MCT injection modulate the hepatic oxidative stresses induced by MCT in various extents.

Proanthocyanidin Attenuation of Oxidative Stress and NF- κ B Protects Apolipoprotein E-Deficient Mice against Diabetic Nephropathy

Hyperlipidemia and hyperglycemia result in oxidative stress and play a major role in the development of diabetic nephropathy (DN). We explored the effects of proanthocyanidin (PA) on the induction and progression of DN in apolipoprotein E-deficient mice. Diabetes Mellitus was induced in ten-week-old male apoE^−/−mice using streptozotocin (STZ). Mice were fed with a high-fat diet in presence or absence of PA. PA treatment significantly reduced the high cholesterol levels, restored renal functions, and reduced albuminuria in the PA-treated diabetic mice compared with the diabetic untreated mice. In addition, the glomerular mesangial expansion in the diabetic mice was attenuated as a result of PA supplementation. Moreover, PA treatment restored the elevated levels of MDA and CML and the reduced activity of SOD and GSH in the diabetic mice. Furthermore, PA feeding reduced the activation and translocation of NF-κB to the nucleus compared with the diabetic untreated animals. Reduction of NF-κB activation resulted in the attenuation of the expression of IL-6, TGFβ, and RAGE which protected PA-treated mice against DN. The renoprotective effects of PA were found to be time independent regardless of whether the dietary feeding with PA was started pre-, co-, or post-STZ injection. In conclusion, part of the beneficial effects of PA includes the disruption of the detrimental AGE-RAGE-NFκB pathways.

Nox4 and diabetic nephropathy: with a friend like this, who needs enemies?

Oxidative stress has been linked to the pathogenesis of diabetic nephropathy, a complication of diabetes in the kidney. NADPH oxidases of the Nox family are a major source of reactive oxygen species in the diabetic kidney and are critical mediators of redox signaling in glomerular and tubulointerstitial cells exposed to the diabetic milieu. Here, we present an overview of the current understanding of the roles of Nox catalytic and regulatory subunits in the processes that control mesangial cell, podocyte, and tubulointerstitial cell injury induced by hyperglycemia and other predominant factors enhanced in the diabetic milieu, including the renin-angiotensin system and transforming growth factor-β. The role of the Nox isoform Nox4 in the redox processes that alter renal biology in diabetes is highlighted.

Inhibitory effect of α-lipoic acid on thioacetamide-induced tumor promotion through suppression of inflammatory cell responses in a two-stage hepatocarcinogenesis model in rats

To investigate the protective effect of α-lipoic acid (a-LA) on the hepatocarcinogenic process promoted by thioacetamide (TAA), we used a two-stage liver carcinogenesis model in N-diethylnitrosamine (DEN)-initiated and TAA-promoted rats. We examined the modifying effect of co-administered a-LA on the liver tissue environment surrounding preneoplastic hepatocellular lesions, with particular focus on hepatic macrophages and the mechanism behind the decrease in apoptosis of cells surrounding preneoplastic hepatocellular lesions during the early stages of hepatocellular tumor promotion. TAA increased the number and area of glutathione S-transferase placental form (GST-P)(+) liver cell foci and the numbers of proliferating and apoptotic cells in the liver. Co-administration with a-LA suppressed these effects. TAA also increased the numbers of ED2(+), cyclooxygenase-2(+), and heme oxygenase-1(+) hepatic macrophages as well as the number of CD3(+) lymphocytes. These effects were also suppressed by a-LA. Transcript levels of some inflammation-related genes were upregulated by TAA and downregulated by a-LA in real-time RT-PCR analysis. Outside the GST-P(+) foci, a-LA reduced the numbers of apoptotic cells, active caspase-8(+) cells and death receptor (DR)-5(+) cells. These results suggest that hepatic macrophages producing proinflammatory factors may be activated in TAA-induced tumor promotion. a-LA may suppress tumor-promoting activity by suppressing the activation of these macrophages and the subsequent inflammatory responses. Furthermore, a-LA may suppress tumor-promoting activity by suppressing the DR5-mediated extrinsic pathway of apoptosis and the subsequent regeneration of liver cells outside GST-P(+) foci.

Nox as a target for diabetic complications

Oxidative stress has been linked to the pathogenesis of the major complications of diabetes in the kidney, the heart, the eye or the vasculature. NADPH oxidases of the Nox family are a major source of ROS (reactive oxygen species) and are critical mediators of redox signalling in cells from different organs afflicted by the diabetic milieu. In the present review, we provide an overview of the current knowledge related to the understanding of the role of Nox in the processes that control cell injury induced by hyperglycaemia and other predominant factors enhanced in diabetes, including the renin–angiotensin system, TGF-β (transforming growth factor-β) and AGEs (advanced glycation end-products). These observations support a critical role for Nox homologues in diabetic complications and indicate that NADPH oxidases are an important therapeutic target. Therefore the design and development of small-molecule inhibitors that selectively block Nox oxidases appears to be a reasonable approach to prevent or retard the complications of diabetes in target organs. The bioefficacy of these agents in experimental animal models is also discussed in the present review.

Discovery of pluripotency-associated microRNAs in rabbit preimplantation embryos and embryonic stem-like cells

MicroRNAs (miRNAs) are small non-coding RNAs that regulate multiple biological processes. Increasing experimental evidence implies an important regulatory role of miRNAs during embryonic development and in embryonic stem (ES) cell biology. In the current study, we have described and analyzed the expression profile of pluripotency-associated miRNAs in rabbit embryos and ES-like cells. The rabbit specific ocu-miR-302 and ocu-miR-290 clusters, and three homologs of the human C19MC cluster (ocu-miR-512, ocu-miR-520e, and ocu-miR-498) were identified in rabbit preimplantation embryos and ES-like cells. The ocu-miR-302 cluster was highly similar to its human homolog, while ocu-miR-290 revealed a low level of evolutionary conservation with its mouse homologous cluster. The expression of the ocu-miR-302 cluster began at the 3.5 days post-coitum early blastocyst stage and they stayed highly expressed in rabbit ES-like cells. In contrast, a high expression level of the ocu-miR-290 cluster was detected during preimplantation embryonic development, but a low level of expression was found in rabbit ES-like cells. Differential expression of the ocu-miR-302 cluster and ocu-miR-512 miRNA was detected in rabbit trophoblast and embryoblast. We also found that Lefty has two potential target sites in its 3′UTR for ocu-miR-302a and its expression level increased upon ocu-miR-302a inhibition. We suggest that the expression of the ocu-miR-302 cluster is characteristic of the rabbit ES-like cell, while the ocu-miR-290 cluster may play a crucial role during early embryonic development. This study presents the first identification, to our knowledge, of pluripotency-associated miRNAs in rabbit preimplantation embryos and ES-like cells, which can open up new avenues to investigate the regulatory function of ocu-miRNAs in embryonic development and stem cell biology.

Involvement of multiple cell cycle aberrations in early preneoplastic liver cell lesions by tumor promotion with thioacetamide in a two-stage rat hepatocarcinogenesis model

Thioacetamide (TAA) induces oxidative stress and hepatocarcinogenicity in rats. We previously reported that TAA promotion caused various disruptions in cell cycle protein expression in rats, including downregulation of p16(Ink4a), which is associated with intraexonic hypermethylation in hepatocellular proliferative lesions. This study further investigated the contribution of cell cycle aberrations associated with early hepatocarcinogenic processes induced by TAA using antioxidants, enzymatically modified isoquercitrin (EMIQ) and α-lipoic acid (ALA), in a two-stage rat hepatocarcinogenesis model. TAA-promotion after initiation with N-diethylnitrosamine increased the number and area of hepatocellular foci immunoreactive for glutathione S-transferase placental form (GST-P) and the numbers of proliferating and apoptotic cells. Co-treatment with EMIQ and ALA suppressed these increases. TAA-induced formation of p16(Ink4a-) foci in concordance with GST-P(+) foci was not suppressed by co-treatment with EMIQ or ALA. TAA-promotion increased cellular distributions of cell proliferation marker Ki-67, G2/M and spindle checkpoint proteins (phosphorylated checkpoint kinase 1 and Mad2), the DNA damage-related protein phosphorylated histone H2AX, and G2-M phase-related proteins (topoisomerase IIα, phosphorylated histone H3 and Cdc2) within GST-P(+) foci, and co-treatment with EMIQ or ALA suppressed these increases. These results suggest that downregulation of p16(Ink4a) may allow selective proliferation of preneoplastic cells by TAA promotion. However, antioxidants did not counteract this gene control. Moreover, effective suppression of TAA-induced cellular population changes within preneoplastic lesions by antioxidants may reflect facilitation of cell cycling and accumulation of DNA damage causing the activation of cell cycle checkpoints, leading to G2 and M phase arrest at the early stages of hepatocarcinogenesis promoted by TAA.

Molecular mechanisms in the pathogenesis of diabetic nephropathy: an update

Diabetes mellitus is known to trigger retinopathy, neuropathy and nephropathy. Diabetic nephropathy, a long-term major microvascular complication of uncontrolled hyperglycemia, affects a large population worldwide. Recent findings suggest that numerous pathways are activated during the course of diabetes mellitus and that these pathways individually or collectively play a role in the induction and progression of diabetic nephropathy. However, clinical strategies targeting these pathways to manage diabetic nephropathy remain unsatisfactory, as the number of diabetic patients with nephropathy is increasing yearly. To develop ground-breaking therapeutic options to prevent the development and progression of diabetic nephropathy, a comprehensive understanding of the molecular mechanisms involved in the pathogenesis of the disease is mandatory. Therefore, the purpose of this paper is to discuss the underlying mechanisms and downstream pathways involved in the pathogenesis of diabetic nephropathy.

Diabetic nephropathy and antioxidants

CONTEXT

Oxidative stress has crucial role in pathogenesis of diabetic nephropathy (DN). Despite satisfactory results from antioxidant therapy in rodent, antioxidant therapy showed conflicting results in combat with DN in diabetic patients.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar,Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched.

RESULTS

Treatment of DN in human are insufficient with rennin angiotensin system (RAS) blockers, so additional agent ought to combine with this management. Meanwhile based on DN pathogenesis and evidences in experimental and human researches, the antioxidants are the best candidate. New multi-property antioxidants may be improved human DN that show high power antioxidant capacity, long half-life time, high permeability to mitochondrion, improve body antioxidants enzymes activity and anti-inflammatory effects.

CONCLUSIONS

Based on this review and our studies on diabetic rats, rosmarinic acid a multi-property antioxidant may be useful in DN patients, but of course, needs to be proven in clinical trials studies.

Oxidative stress and diabetic kidney disease

The number of people with diabetic kidney disease continues to increase worldwide despite current treatments. Of the pathophysiologic mechanisms that have been identified in the development and progression of diabetic nephropathy, oxidative stress (more accurately described as increased levels of reactive oxygen species; ROS) is of major importance. The increase in ROS is due to both increased production and to decreased and/or inadequate antioxidant function. To date, human clinical trials with antioxidants have not been shown to be effective. This is likely due, at least in part, to the lack of specificity of current agents. Recent research has determined both major sources of high glucose-induced cellular ROS production as well as high glucose-induced changes in antioxidant function. Treatments targeted at one or more of the specific diabetes-induced alterations in the regulation of ROS levels will likely lead to effective treatments that prevent the development and progression of diabetic kidney disease.

α-Lipoic acid protects diabetic apolipoprotein E-deficient mice from nephropathy

AIM

Both hyperglycemia and hyperlipidemia increase oxidative stress and contribute to the development of diabetic nephropathy (DN). We investigated the effects of α-lipoic acid, a natural antioxidant and a cofactor in the multienzyme complexes, on the development of DN in diabetic apolipoprotein E-deficient mice.

METHODS

Twelve-week-old male apoE-/- mice on C57BL/6J genetic background were made diabetic with injections of streptozotocin (STZ). STZ-treated diabetic apoE-/- mice and non-diabetic control were fed with a synthetic high-fat (HF) diet with or without lipoic acid (LA) supplementation. Multiple parameters including plasma glucose, cholesterol, oxidative stress markers, cytokines, and kidney cortex gene expression, and glomerular morphology were evaluated.

RESULTS

LA supplementation markedly protected the β cells, reduced cholesterol levels, and attenuated albuminuria and glomerular mesangial expansion in the diabetic mice. Renoprotection by LA was equally effective regardless of whether the dietary supplementation was started 4 weeks before, simultaneously with, or 4 weeks after the induction of diabetes by STZ. LA supplementation significantly improved DN and oxidative stress in the diabetic mice. Severity of albuminuria was positively correlated with level of thiobarbituric acid reactive substances (TBARs) in the kidney (r(2)=0.62, P<.05). Diabetes significantly changed the kidney expression of Rage, Sod2, Tgfb1 and Ctgf, Pdp2, nephrin, and Lias. LA supplementation corrected these changes except that it further suppressed the expression of the Lias gene coding for lipoic acid synthase.

CONCLUSIONS

Our data indicate that LA supplementation effectively attenuates the development and progression of DN through its antioxidant effect as well as enhances glucose oxidation.

The effect of the uremic toxin cyanate (CNO⁻) on anaerobic cysteine metabolism and oxidative processes in the rat liver: a protective effect of lipoate

Chronic renal failure (CRF) patients have an increased plasma level of urea, which can be a source of cyanate. This compound can cause protein carbamoylation thereby changing biological activity of proteins. Therefore, in renal failure patients, cyanate can disturb metabolism and functioning of the liver. This work presents studies demonstrating that the treatment of rats with cyanate alone causes the following changes in the liver: (1) inhibition of rhodanese (TST), cystathionase (CST) and 3-mercaptopyruvate sulfotransferase (MPST) activities, (2) decrease in sulfane sulfur level (S*), (3) lowering of nonprotein sulfhydryl groups (NPSH) group level, and (4) enhancement of prooxidant processes (rise in reactive oxygen species (ROS) and malondialdehyde (MDA) level). This indicates that cyanate inhibits anaerobic cysteine metabolism and shows prooxidant action in the liver. Out of the above-mentioned changes, lipoate administered with cyanate jointly was able to correct MDA, ROS and NPSH levels, and TST activity. It had no significant effect on MPST and CST activities. It indicates that lipoate can prevent prooxidant cyanate action and cyanate-induced TST inhibition. These observations can be promising for CRF patients since lipoate can play a dual role in these patients as an efficient antioxidant defense and a protection against cyanate and cyanide toxicity.

D-galactose effectiveness in modeling aging and therapeutic antioxidant treatment in mice

Accumulating evidence suggests that mitochondrial dysfunction and oxidative stress play major roles in aging. Chronic administration of D-galactose has been reported to cause deterioration of cognitive and motor skills that are similar to symptoms of aging and, therefore, is regarded as a model of accelerated aging. Because enhancing endogenous antioxidants is now widely regarded as an attractive therapy for conditions associated with mitochondrial oxidative stress, in the present study the effects of α-lipoic acid, L-carnitine, and PMX-500F on D-galactose treated mice were tested. Female mice were injected with (100 mg/kg) D-(+)-galactose for 6 weeks and some groups were treated with a daily dose of α-lipoic acid (5 mg/kg), L-carnitine (3.9 mg/kg), PMX-500F (11.9 mg/kg), or the vehicle (0.1 M Tris, pH 7.4). Control mice were treated with physiological saline. An accelerating Rota-Rod, open field test, and Y-maze test were performed, and serum lactate concentrations were analyzed. These analyses did not identify impairment in motor coordination, open-field activity, or spatial memory (p > 0.05). Similarly, serum lactate concentrations in D-galactose-treated mice were not elevated when compared to controls (p > 0.05). Treatment with the antioxidant compounds at the given concentrations did not result in any changes in the behavioral parameters tested. In conclusion, results of this study illustrate that chronic, short-term D-galactose treatment may not represent a suitable model for inducing readily detectable age-related neurobehavioral symptoms in mice.

Satureja khozestanica essential oil ameliorates progression of diabetic nephropathy in uninephrectomized diabetic rats

Diabetic nephropathy is the common cause of leading to end stage of renal disease (ESRD). Satureja khozestanica essential oil (SKEO) was used as an antioxidant and antidiabetic for the inhibition of diabetic nephropathy. Forty male rats were uninephrectomized and divided in four groups randomly; group one as control, group two diabetic untreatment, groups three and four treatment with SKEO by 250 or 500 ppm in drinking water, respectively. Diabetes was induced in the second, third and fourth groups by alloxan injection subcutaneously. After eight weeks treatment, serum malondialdehyde, serum creatinine and serum urea were measured. The kidney paraffin sections were stained by periodic acid Schiff method. Glomerular volume and glomerular number were estimated by stereological rules. Glomerular sclerosis was studied semi-quantitatively. The means were compared by SPSS 13 software and Mann-Whitney test at p<0.05. Satureja khozestanica essential oil (250 or 500 ppm) significantly inhibited the progression of glomerular hypertrophy, glomerular number loss, glomerulosclerosis, lipid peroxidation, serum urea and creatinine compared with the diabetic untreated group. The level of glomerular number, serum malondialdehyde, serum creatinine and urea in the treated groups was significantly maintained at the same level as that of the control group. In conclusion, satureja essential oil significantly can ameliorate glomerular hypertrophy, loss of glomerular number, glomerulosclerosis and attenuated serum urea and serum creatinine in diabetic rats.

Characterization of embryonic stem cell lines derived from New Zealand white rabbit embryos

The purposes of this study were to examine technical details in deriving and maintaining rabbit embryonic stem (rES) cell lines and to analyze their characteristics. When STO cells were used as feeder cells, no rES cell lines were established using either intact blastocysts or inner cell masses (ICMs). On the mouse embryonic fibroblasts (MEF) feeder, rES cell lines were efficiently (24%) derived. Addition of leukemia inhibitory factor (LIF) to the cells cultured on the MEF feeders further increased the derivation efficiency (57%) of rES cells. The fact that LIF induced serine-phosphorylation of STAT3 suggested LIF-dependent maintenance of rES cells. Most of the rES cell lines expressed AP, SSEA-4, Oct4, TRA-1-60, and TRA-1-81. Western blot or RT-PCR analysis also confirmed the expression of Oct4, Nanog, and Sox2. When induced to form EBs in vitro or injected to the severe combined immunodeficiency (SCID) mice, the rES cells generated embryoid bodies (EBs) and teratomas with three germ layers expressing the marker genes including MAP2, Desmin, and GATA4, respectively. In conclusion, rabbit ES cell lines can be efficiently established using our current protocols with LIF supplement. These ES cells express pluripotent stem cell markers and retain their capability to differentiate into different tissue cells. Furthermore, rES cells depend on LIF for self-renewal, likely via the JAK-STAT pathway.