Melatonin decreases apoptosis and expression of apoptosis-associated proteins in acute puromycin aminonucleoside nephrosis

Apoptosis in post-streptococcal glomerulonephritis and mechanisms for failed of inflammation resolution

Post-streptococcal glomerulonephritis is a condition resulting from infection by group A beta-hemolytic streptococcus. The main mechanism involves the formation of immune complexes formed in the circulation or in situ on the glomerular basement membrane, which activates complement and causes various inflammatory processes. Cellular mechanisms have been reported in the induction of kidney damage represented by the infiltration of innate cells (neutrophils and monocyte/macrophages) and adaptive cells (CD4 + lymphocytes and CD8 + lymphocytes) of the immune system. These cells induce kidney damage through various mechanisms. It has been reported that nephritogenic antigens are capable of inducing inflammatory processes early, even before the formation of immune complexes. Usually, this disease progresses towards clinical and renal normalization; however, in a smaller number of patients, it evolves into chronicity and persistent kidney damage. Hypotheses have been proposed regarding the mechanisms underlying this progression to chronicity including failure to induce apoptosis and failure to phagocytose apoptotic cells, allowing these cells to undergo membrane permeabilization and release pro-inflammatory molecules into the environment, thereby perpetuating renal inflammation. Other mechanisms involved include persistent infection, genetic background of the host's complement system, tubulointerstitial changes, and pre-existing kidney damage due to old age and comorbidities.

JM. Antioxidant Actions of Melatonin: A Systematic Review of Animal Studies

Melatonin is an indoleamine with crucial antioxidant properties that are used to combat inflammatory and neoplastic processes, as well as control transplants. However, the clinical applications of melatonin have not yet been fully consolidated in the literature and require in-depth analysis.

OBJECTIVES

This study reviewed the literature on the antioxidant properties of melatonin in rat models.

METHODS

We followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analyses and used the PubMed, LILACS, and Cochrane databases, Google Scholar, and article references, irrespective of publication time.

RESULTS

Ten articles involving 485 rats were selected, and the effects of melatonin on antioxidant markers were investigated. Melatonin increased superoxide dismutase in nine studies, glutathione peroxidase in seven studies, and catalase in five studies. In contrast, melatonin reduced glutathione in three studies and malonaldehyde in seven of eight studies.

CONCLUSION

Our findings suggest that melatonin effectively reduces oxidative stress.

Inhibition of NF-κB signaling pathway by astaxanthin supplementation for prevention of heat stress-induced inflammatory changes and apoptosis in Karan Fries heifers

Present study was conducted on 12 Karan Fries (Holstein Friesian X Tharparkar) heifers (10-12 months) to assess the effect of astaxanthin supplementation on heat stress amelioration and inhibition of NF-κB signaling pathway for prevention of heat stress-induced inflammatory changes and apoptosis in the cell during the summer season. The heifers were randomly and equally divided into two groups, i.e., control (fed as per ICAR 2013) and treatment groups (additionally supplemented astaxanthin at a dose rate of 0.25 mg/kg BW/day/animal). Temperature humidity index used to assess the levels of summer stress during the experimental period. Blood samples were collected at the fortnightly interval for quantification of plasma cortisol and IL-12 from both the groups of the heifers and from collected blood samples, RNA was isolated and transcribed into cDNA for real time PCR, for genes expression of NF-κB, IL-2, caspase-3, and Bcl-2. Plasma cortisol, IL-12 levels, and expression pattern of NF-κB, IL-2, and caspase-3 were significantly (P ≤ 0.05) lower in treatment group of Karan Fries heifers than control group, whereas, Bcl-2 was higher (P ≤ 0.05) in astaxanthin supplemented group. The temperature humidity index had a positive correlation (P ≤ 0.05) with plasma cortisol and IL-12 and expression pattern of NF-κB, IL-2, and caspase-3. However, it was negatively correlated with Bcl-2. The supplementation of astaxanthin can ameliorate the impact of summer stress through NF-κB downregulation, might be due to the quenching of free radicals, which regulates the expression of pro-inflammatory mediators and apoptotic genes.

Does melatonin influence the apoptosis in rat uterus of animals exposed to continuous light?

Melatonin has been described as a protective agent against cell death and oxidative stress in different tissues, including in the reproductive system. However, the information on the action of this hormone in rat uterine apoptosis is low. Our objective was to evaluate the effects of melatonin on mechanisms of cell death in uterus of rats exposed to continuous light stress. Twenty adult Wistar rats were divided into two groups: GContr (vehicle control) and GExp which were treated with melatonin (0.4 mg/mL), both were exposed to continuous light for 90 days. The uterus was removed and processed for quantitative real time PCR (qRT-PCR), using PCR-array plates of the apoptosis pathway; for immunohistochemistry and TUNEL. The results of qRT-PCR of GEXP group showed up-regulation of 13 and 7, pro-apoptotic and anti-apoptotic genes, respectively, compared to GContr group. No difference in pro-apoptotic proteins (Bax, Fas and Faslg) expression was observed by immunohistochemistry, although the number of TUNEL-positive cells was lower in the group treated with melatonin compared to the group not treated with this hormone. Our data suggest that melatonin influences the mechanism and decreases the apoptosis in uterus of rats exposed to continuous light.

Melatonin controlled apoptosis and protected the testes and sperm quality against bisphenol A-induced oxidative toxicity

Epidemiological reports have indicated a correlation between the increasing bisphenol A (BPA) levels in the environment and the incidence of male infertility. In this study, the protective effects of melatonin on BPA-induced oxidative stress and apoptosis were investigated in the rat testes and epididymal sperm. Melatonin (10 mg/kg body weight (bw)) was injected concurrently with BPA (50 mg/kg bw) for 3 and 6 weeks. The administration of BPA significantly increased oxidative stress in the testes and epididymal sperm. This was associated with a decrease in the serum testosterone level as well as sperm quality, chromatin condensation/de-condensation level, and the percentage of haploid germ cells in the semen. BPA administration caused a significant increase in apoptosis accompanied by a decrease in the expression of the antiapoptotic proteins Bcl-2 in the testes and epididymal sperm. The concurrent administration of melatonin decreased oxidative stress by modulating the levels of glutathione, superoxide dismutase, and catalase as well as the malondialdehyde and hydrogen peroxide concentrations in the testes and sperm. Melatonin sustained Bcl-2 expression and controlled apoptosis. Furthermore, melatonin maintained the testosterone levels, ameliorated histopathological changes, increased the percentages of seminal haploid germ cells, and protected sperm chromatin condensation process, indicating appropriate spermatogenesis with production of functional sperm. In conclusion, melatonin protected against BPA-induced apoptosis by controlling Bcl-2 expression and ameliorating oxidative stress in the testes and sperm. Thus, melatonin is a promising pharmacological agent for preventing the potential reproductive toxicity of BPA following occupational or environmental exposures.

Protective effects of captopril in diabetic rats exposed to ischemia/reperfusion renal injury

Objectives

To investigate the potential protective effects of captopril, the angiotensin-converting enzyme inhibitor, in diabetic rats exposed to ischaemia/reperfusion (I/R) renal injury.

Methods

Following successful induction of diabetes, captopril treatment (50 mg/kg/day, p.o.) was applied for 4 weeks, after which bilateral renal ischaemia was induced for 30 min followed by reperfusion for 24 h.

Results

Captopril significantly attenuated hyperglycaemia and hypoinsulinaemia in diabetic rats, and significantly reduced the elevations of serum creatinine and aldosterone levels, and renal malondialdehyde, tumour necrosis factor-α and nitric oxide (NO), and prevented the depletion of reduced glutathione caused by I/R in diabetic rats. Histopathological renal tissue damage induced by I/R in diabetic rats was ameliorated by captopril treatment. Immunohistochemical analysis revealed that captopril significantly attenuated the reduction of insulin content in pancreatic islet β-cells, and decreased the I/R-induced expression of inducible NO synthase, nuclear factor-κB, Fas ligand and caspase-3, and increased the expression of survivin and heme oxygenase-1 in the kidney tissue of diabetic rats.

Conclusions

Captopril represents a potential candidate to reduce the risk of renal injury induced by ischaemia/reperfusion in type 2 diabetes.

Protective effects of melatonin against formaldehyde-induced oxidative damage and apoptosis in rat testes: an immunohistochemical and biochemical study

This study investigated the protective effects of melatonin against formaldehyde-induced oxidative damage and apoptosis in rat testes. A total of 21 male Wistar rats were divided into three groups. Group I was used as a control, Group II was injected every other day with formaldehyde for 1 month, whereas Group III was injected every other day with formaldehyde and melatonin for 1 month. At the end of the experimental period animals were sacrificed and the testes removed and dissected from the surrounding tissues for immunohistochemical evaluation. In addition, the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) were determined. The levels of SOD and GSH-Px decreased significantly, whereas the level of MDA significantly increased in animals treated with formaldehyde compared with the controls. Apoptosis of spermatogenetic and Leydig cells of testicular tissues was observed. In contrast, rats with melatonin SOD and GSH-Px enzyme activity increased whereas MDA levels decreased with formaldehyde exposure along with apoptosis. In view of the present findings, it is suggested that melatonin treatment may prevent formaldehyde-induced oxidative damage and apoptosis in rat testes.

Protective effects of antithrombin on puromycin aminonucleoside nephrosis in rats

We investigated the effects of antithrombin, a plasma inhibitor of coagulation factors, in rats with puromycin aminonucleoside-induced nephrosis, which is an experimental model of human nephrotic syndrome. Antithrombin (50 or 500 IU/kg/i.v.) was administered to rats once a day for 10 days immediately after the injection of puromycin aminonucleoside (50 mg/kg/i.v.). Treatment with antithrombin attenuated the puromycin aminonucleoside-induced hematological abnormalities. Puromycin aminonucleoside-induced renal dysfunction and hyperlipidemia were also suppressed. Histopathological examination revealed severe renal damage such as proteinaceous casts in tubuli and tubular expansion in the kidney of control rats, while an improvement of the damage was seen in antithrombin-treated rats. In addition, antithrombin treatment markedly suppressed puromycin aminonucleoside-induced apoptosis of renal tubular epithelial cells. Furthermore, puromycin aminonucleoside-induced increases in renal cytokine content were also decreased. These findings suggest that thrombin plays an important role in the pathogenesis of puromycin aminonucleoside-induced nephrotic syndrome. Treatment with antithrombin may be clinically effective in patients with nephrotic syndrome.

Melatonin inhibits oxidative stress and apoptosis in fetal brains of hyperhomocysteinemic rat dams

Moderate hyperhomocysteinemia is a risk factor for neurodegenerative diseases and complications during pregnancy. Increased homocysteine levels during pregnancy may elevate developmental risk on fetal brain structure and function. However, little is known about the mechanism of action of homocysteine on the degeneration of the fetal brain. Hence in this study, we examined the effects of maternal hyperhomocysteinemia on oxidative stress and apoptosis in brain tissues and investigated whether administration of melatonin to the mother would prevent homocysteine-induced oxidative cerebral damage in pups. Hyperhomocysteinemia was induced in female rats by administration of methionine at a dose of 1 g/kg body weight dissolved in drinking water during pregnancy. Some animals received methionine plus 10 mg/kg/day melatonin subcutaneously throughout pregnancy. After delivery, the level of lipid peroxidation (malondialdehyde + 4-hydroxyalkenals) was determined in different subfractions of pup brains. Furthermore, DNA fragmentation, levels of Bcl-2 protein and p53 mRNA expression were determined to evaluate apoptosis. Significant elevation was found in the levels of lipid peroxidation in subcellular fractions of the brain of pups of hyperhomocysteinemic dams. Increased DNA fragmentation and p53 mRNA expression was observed in the brain of pups of homocysteine-treated rats, while a significant reduction was seen in the levels of anti-apoptotic Bcl-2 levels. Melatonin administration prevented markers of oxidative stress and biochemical signs of apoptosis. In conclusion, therapeutic administration of melatonin protects against the induction of oxidative stress and neural tissue injury and might prevent congenital malformations of fetal brain caused by maternal hyperhomocysteinemia.

Effects of maternal uninephrectomy on the development of fetal rat kidney: apoptosis and the expression of oncogenes

The present study was designed to explore whether maternal uninephrectomy affects development of the collecting ducts in fetal kidney. Localization of DNA fragmented cells in the kidney of fetal rats from uninephrectomized mothers were examined by the terminal deoxynucleotidyl transferase (TdT)-mediated d-UTP-biotin nick end labeling (TUNEL) method. Immunohistochemistry was used to examine the localizations of bcl-2 gene products. The gene expressions for bcl-2, p53, and WT1 mRNAs were examined by using the semi-quantitative reverse transcript-polymerase chain reaction. TUNEL positive cells were more numerous in the medullary collecting ducts of the fetuses from uninephrectomized mothers than in those of the fetuses from sham-operated ones. The expressions of bcl-2, p53, and WT1 mRNAs were lower in the fetuses from uninephrectomized mothers than in the fetuses from sham-operated ones. Cells in the medullary collecting ducts showed positive reactions to anti-bcl-2 gene products antibody with the reactions being weaker in the fetuses from uninephrectomized mothers. These results showed that maternal uninephrectomy accelerated the development of fetal rat kidney and it was associated with the lowered the expression of bcl-2 in fetal rat kidney.

Prostaglandin E2 promotes cell survival of glomerular epithelial cells via the EP4 receptor

Visceral glomerular epithelial cells (GEC) are crucial for glomerular permselectivity and structural integrity in the kidney. The current study addressed the role of cyclooxygenase (COX)-2 and its product prostaglandin (PG) E2 in GEC survival. We generated a subclone of cultured rat GEC, which overexpress COX-2 in an inducible manner. When COX-2 was induced, GEC survived better in serum-deprived conditions. Induction of COX-2 was correlated with increased PGE2 generation, increased activation of extracellular signal-regulated kinase, decreased apoptosis, and increased cell proliferation. Rat GEC abundantly expressed the EP4 isoform of PGE2 receptor. Induction of COX-2 and addition of exogenous PGE2 both lead to decreased serum deprivation-induced apoptosis, which was accompanied by activation of the survival kinase Akt. Anti-apoptotic effect of COX-2 induction was reversed by the specific inhibitor of the EP4 receptor, L-161982. PGE2 also inhibited puromycin aminonucleoside-induced GEC apoptosis in vitro. Acute puromycin aminonucleoside nephrosis (PAN) is a rat model of GEC injury and proteinuria. In rats with PAN, glomerular apoptosis, quantified as caspase-3 activity, as well as urinary protein excretion were significantly increased, compared with control rats. Administration of L-161982 in rats with PAN further exacerbated caspase-3 activation and proteinuria. Thus COX-2 and its product PGE2 may have anti-apoptotic/protective effect on GEC via the EP4 receptor of PGE2.

Dexamethasone Prevents Podocyte Apoptosis Induced by Puromycin Aminonucleoside: Role of p53 and Bcl-2–Related Family Proteins

Nephrotic-range proteinuria is due to glomerular diseases characterized by podocyte injury. Glucocorticoids are the standard of care for most forms of nephrotic syndrome. However, the precise mechanisms underlying the beneficial effects of glucocorticoids on podocytes, beyond its general immunosuppressive and anti-inflammatory effects, are still unknown. This study tested the hypothesis that the synthetic glucocorticoid dexamethasone directly reduces podocyte apoptosis. Growth-restricted immortalized mouse podocytes in culture were exposed to puromycin aminonucleoside (PA) to induce apoptosis. Our results showed that dexamethasone significantly reduced PA-induced apoptosis by 2.81-fold. Dexamethasone also rescued podocyte viability when exposed to PA. PA-induced apoptosis was associated with increased p53 expression, which was completely blocked by dexamethasone. Furthermore, the inhibition of p53 by the p53 inhibitor pifithrin-alpha protected against PA-induced apoptosis. Dexamethasone also lowered the increase in the proapoptotic Bax, which was increased by PA, and increased expression of the antiapoptotic Bcl-xL protein. Moreover, the decrease in p53 by dexamethasone was associated with increased Bcl-xL levels. Podocyte apoptosis induced by PA was caspase-3 independent but was associated with the translocation of apoptosis-inducing factor (AIF) from the cytoplasm to nuclei. AIF translocation was inhibited by dexamethasone. These results show that PA-induced podocyte apoptosis is p53 dependent and associated with changes in Bcl-2-related proteins and AIF translocation. The protective effects of dexamethasone on PA-induced apoptosis were associated with decreasing p53, increasing Bcl-xL, and inhibition of AIF translocation. These novel findings provide new insights into the beneficial effects of corticosteroids on podocytes directly, independent of its immunosuppressive effects.

Increased glomerular and extracellular malondialdehyde levels in patients and rats with focal segmental glomerulosclerosis

BACKGROUND

Evidence suggests an increase in oxidative stress in patients with chronic kidney disease, as glomerulosclerosis is the prerequisite for chronic kidney disease; whether the oxidative stress already exists early on is not known.

MATERIALS AND METHODS

In this study we measured the plasma and urinary levels of malondialdehyde (MDA), the end product of lipid peroxidation, and assessed the immunoreactivity of MDA and superoxide dismutase (SOD) in glomeruli of patients and rats with primary focal segmental glomerulosclerosis (FSGS), and compared our findings with those of minimal change disease (MCD) and normal controls (NC).

RESULTS

Our results showed that plasma MDA level was significantly increased in patients with FSGS compared with both patients with MCD and normal controls. The urinary MDA level was also significantly increased and was significantly correlated with plasma MDA level in patients with FSGS. The immunostaining for glomerular MDA and SOD was significantly higher in the patients with FSGS than in either the patients with MCD or NC, and was also significantly higher in rats with puromycin aminonucleoside (PAN)-induced FSGS than in rats with MCD. Glomerular MDA level was significantly correlated with the degree of glomerulosclerosis in the patients with FSGS.

CONCLUSIONS

Our data suggest that oxidative stress occurs early on before the onset of renal failure, and may play an important role in the pathogenesis of glomerulosclerosis.