The effects of the melatonin treatment on the oxidative stress and apoptosis in diabetic eye and brain

Melatonin and probiotic administration ameliorated hyperglycaemia, oxidative stress, and enhanced cytoprotective effect on beta-cells of diabetic rats

Objective

The study aimed at investigating the effects of administering melatonin and a probiotic to streptozotocin-induced diabetic rats on hyperglycaemia, oxidative stress biomarkers and beta-cells.

Design

Type 1 diabetes was induced in 5 months-old male Wistar rats by single intraperitoneal (i.p.) administration of freshly-prepared STZ (60 mg/kg body weight). Six groups of 10 rats were used and treated once daily for six weeks; (1) Healthy control: normal saline only; (2) Pre-treated with Melatonin (MEL); (3) Diabetic control; (4) Diabetic + Treated with MEL; (5) Diabetic + Treated with Probiotic (Prob); (6) Diabetic + Treated with MEL + Prob. Blood glucose, body weight, activities of antioxidant enzymes and malondialdehyde concentration in serum and tissues, reduced glutathione and immunohistochemical assay. Data obtained were expressed as mean ± standard error of the mean (Mean ± SEM) and subjected to ANOVA followed by Tukey's post hoc test.

Results

Melatonin + Probiotic significantly decreased blood glucose concentrations in diabetic treated rats, compared to the diabetic control rats. MEL + Probiotic increased (p < 0.05) superoxide dismutase activity in serum and liver of diabetic rats. MEL + Probiotic reduced (p < 0.05) malondialdehyde concentration in the serum, liver and kidneys, respectively. MEL + Probiotic treated diabetic rats displayed islets with much greater content of insulin.

Conclusion

Melatonin + Probiotic combination was more effective in mitigating hyperglycaemia, oxidative stress, and exerted cytoprotective effect on the beta-cells.

Molsidomine decreases hyperoxia-induced lung injury in neonatal rats

BACKGROUND

The study's objective is to evaluate if Molsidomine (MOL), an anti-oxidant, anti-inflammatory, and anti-apoptotic drug, is effective in treating hyperoxic lung injury (HLI).

METHODS

The study consisted of four groups of neonatal rats characterized as the Control, Control+MOL, HLI, HLI + MOL groups. Near the end of the study, the lung tissue of the rats were evaluated with respect to apoptosis, histopathological damage, anti-oxidant and oxidant capacity as well as degree of inflammation.

RESULTS

Compared to the HLI group, malondialdehyde and total oxidant status levels in lung tissue were notably reduced in the HLI + MOL group. Furthermore, mean superoxide dismutase, glutathione peroxidase, and glutathione activities/levels in lung tissue were significantly higher in the HLI + MOL group as compared to the HLI group. Tumor necrosis factor-α and interleukin-1β elevations associated with hyperoxia were significantly reduced following MOL treatment. Median histopathological damage and mean alveolar macrophage numbers were found to be higher in the HLI and HLI + MOL groups when compared to the Control and Control+MOL groups. Both values were increased in the HLI group when compared to the HLI + MOL group.

CONCLUSIONS

Our research is the first to demonstrate that bronchopulmonary dysplasia may be prevented through the protective characteristics of MOL, an anti-inflammatory, anti-oxidant, and anti-apoptotic drug.

IMPACT

Molsidomine prophylaxis significantly decreased the level of oxidative stress markers. Molsidomine administration restored the activities of antioxidant enzymes. Molsidomine prophylaxis significantly reduced the levels of inflammatory cytokines. Molsidomine may provide a new and promising therapy for BPD in the future. Molsidomine prophylaxis decreased lung damage and macrophage infiltration in the tissue.

Histopathological examination of the protective effect of intense exercise in apoptotic germ cell damage due to diabetes

PURPOSE

The aim of this study was to determine the protective and antioxidative effects of intensive exercise on streptozotocin (STZ)-induced testicular damage, apoptotic spermatognial cells death, and oxidative stress.

METHODS

36 male Sprague Dawley rats were divided into three groups: control, diabetes, and diabetes+intensive exercise (IE) groups. Testicular tissues were examined histopathologically and antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde (MDA) activity, as well as serum testosterone level, were measured.

RESULTS

Seminiferous tubules and germ cells were found to be better in the testis tissue of the intense exercise group than in the diabetes group. Diabetes suppressed antioxidant enzymes CAT, SOD, GPx and testosterone levels were significantly decreased, and increased MDA level in the diabetic group compared to diabetes+IE group (p < 0.001). Following four weeks of treatment, intensive exercise improved the antioxidant defense, significantly decreased MDA activity, and increased testosterone levels in testicular tissue in the diabetic group compared to diabetes+IE group (p < 0.01).

CONCLUSIONS

STZ-induced diabetes causes damage to the testis tissue. In order to prevent these damages, exercise practice has become very popular nowadays. In present study, our intensive exercise protocol, histological, and biochemical analysis of the effect of diabetes on the testicular tissues is shown.

Downregulation of Bax/Bcl-2 Expression During Apoptosis in the Hippocampus of Diabetic Male Wistar Rats: Ameliorative Effects of Peganum harmala Seed Extract

Background

Apoptosis is proposed as a possible mechanism for diabetes-induced hippocampal neuronal cell death. Numerous studies have suggested that the therapeutic properties of plants, such as antioxidant and anti-apoptotic, are effective in improving the complications of diabetes in the hippocampus.

Objectives

This study aimed to evaluate the anti-apoptotic properties of Peganum harmala (P. harmala) in the brain hippocampal cells of diabetic rats.

Methods

In this experimental study, 48 male Wistar rats were divided into six groups (n = 8) as follows: Control (C), diabetic (D), harmine (H), diabetic plus harmine (DH), seed extract (S), and diabetic plus seed extract (DS). A single dose of streptozotocin (STZ) (60 mg/kg) was enough to cause diabetes. Seed extract and harmine were given at 150 mg/kg and 6.5 mg/kg, respectively (daily by oral gavage for 28 days). The glucose levels in the blood were measured, and the histological staining of the hippocampus was examined. Percentages of apoptotic hippocampal cells were identified with flow cytometry. Bax and Bcl-2 expression was assayed via Real time- polymerase chain reaction (PCR) and Western blot.

Results

In DH (P = 0.001) and DS (P = 0.01) rats, the mean fasting blood glucose level significantly reduced compared with the D group. Bax and Bcl-2 expression at both mRNA and protein levels significantly differed between the D group and other groups (P = 0.01). Harmine and the seed extract considerably reduced the Bax/Bcl-2 ratio in the hippocampal cells compared to the D group (P = 0.001).

Conclusions

Streptozotocin-induced apoptosis in the hippocampus of diabetic rats was reduced by administering the seed extract of Peganum harmala. The P. harmala seed extract and its active ingredient, harmine, could be used as anti-apoptotic drugs.

Administration of Melatonin in Diabetic Retinopathy Is Effective and Improves the Efficacy of Mesenchymal Stem Cell Treatment

Stem cell transplantation is a promising therapeutic technique for the treatment of a variety of diseases; nevertheless, stem cell therapy may not always work as well as it could. The goal of this study was to test the hypothesis that employing a powerful antioxidant like melatonin improves stem cell transplantation success and potentiates stem cell function in the therapy of diabetic retinopathy. For this purpose, 50 adult male rats were divided into the following: control group: this group received 0.5 ml of 0.1 M of sodium citrate buffer (pH = 4.5) (intraperitoneal (I.P.)). The confirmed diabetic rats were divided into 4 groups: diabetic group: confirmed diabetic rats received no treatments with a regular follow of the blood glucose profile for 8 weeks; melatonin group: confirmed diabetic rats received melatonin (5 mg/kg/day); stem cell group: the confirmed diabetic rats were given intravitreal injection of stem cells (2 μl cell suspension of stem cells (3 × 10⁴ cells/μl)); and melatonin+stem cell group: confirmed diabetic rats received melatonin (5 mg/kg/day), orally once daily for 8 weeks, and 2 μl cell suspension of stem cells (3 × 10⁴ cells/μl) was carefully injected into the vitreous cavity. Our results showed that administration of melatonin and/or stem cell restored the retinal oxidative/antioxidant redox and reduced retinal inflammatory mediators. Coadministration of melatonin and stem cells enhanced the number of transplanted stem cells in the retinal tissue and significantly reduced retinal BDEF, VEGF, APOA1, and RBP4 levels as compared to melatonin and/or stem alone. We may conclude that rats treated with melatonin and stem cells had their retinal oxidative/antioxidant redox values restored to normal and their histological abnormalities reduced. These findings support the hypothesis that interactions with the BDEF, VEGF, APOA1, and RBP4 signaling pathways are responsible for these effects.

The melatonin MT2 receptor is involved in the anti-apoptotic effects of melatonin in rats with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a widely prevalent chronic disease and risk factor for several other diseases, such as cardiovascular diseases, neuropathy, nephropathy, and retinopathy. Apoptosis is a homeostatic mechanism to maintain cell numbers at a certain level in tissues. Chronic high blood glucose levels might lead to mitochondrial dysfunction and trigger undesirable apoptosis in T2DM. The pineal hormone melatonin has been shown to regulate apoptosis. The aim of this study was to investigate the impact of the melatonin MT₂ receptor in the role of melatonin to prevent undesirable apotosis in different tissues of diabetic rats. Male Sprague Dawley rats were randomly divided into 4 groups; 1. Control group (only vehicle), 2. Diabetic group (streptozotozin/nicotinamide treated), 3. Diabetic group treated with melatonin (500μg/kg/day), and 4. Diabetic group treated with melatonin (500 μg/kg/day for 6 weeks) and the selective MT₂ receptor antagonist luzindole (0.25 g/kg/day for 6 weeks). Various tissue samples (kidney, liver, adipose tissue, pancreas) were removed after 6 weeks for immunohistochemistry and western blot analysis. Our results demonstrated an increased rate of apoptosis in different tissues of diabetic rats compared to controls with melatonin reducing the apoptotic rate in the tissues of rats with T2DM. Furthermore, the anti-apoptotic effects of melatonin were partly mediated by the melatonin MT₂ receptor.

The protective effects of apocynin in hyperoxic lung injury in neonatal rats

AIM

Inflammation and oxidate stress are significant factors in the pathogenesis of bronchopulmonary dysplasia (BPD). The aim of this study is to investigate the efficacy of apocynin (APO), an anti-inflammatory, antioxidant, and antiapoptotic drug, in the prophylaxis of neonatal hyperoxic lung injury.

METHOD

This experimental study included 40 neonatal rats divided into the control, APO, BPD, and BPD + APO groups. The control and APO groups were kept in a normal room environment, while the BPD and BPD + APO groups were kept in a hyperoxic environment. The rats in the APO and BPD + APO groups were administered intraperitoneal APO, while the control and BPD rats were administered ordinary saline. At the end of the trial, lung tissue was evaluated with respect to the degree of histopathological injury, apoptosis, oxidant and antioxidant capacity, and severity of inflammation.

RESULT

The BPD and BPD + APO groups exhibited higher mean histopathological injury and alveolar macrophage scores compared to the control and APO groups. Both scores were lower in the BPD + APO group in comparison to the BPD group. The BPD + APO group had a significantly lower average of TUNEL positive cells than the BPD group. The lung tissue examination indicated significantly higher levels of mean malondialdehyde (MDA), total oxidant status (TOS), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in the BPD group compared to the control and APO groups. While the TNF-α and IL-1β levels of the BPD + APO group were similar to that of the control group, the MDA and TOS levels were higher compared to the controls and lower compared to the BPD group. The BPD group demonstrated significantly lower levels/activities of mean total antioxidant status, glutathione reductase, superoxide dismutase, glutathione peroxidase in comparison to the control and APO groups. While the mean antioxidant enzyme activity of the BPD + APO group was lower than the control group, it was significantly higher compared to the BPD group.

CONCLUSION

This is the first study in the literature to reveal through an experimental neonatal hyperoxic lung injury that APO, an anti-inflammatory, antioxidant, and antiapoptotic drug, exhibits protective properties against the development of BPD.

Does Chrysin prevent severe lung damage in Hyperoxia-Induced lung injury Model?

BACKGROUND

Oxidative stress and inflammation play a critical role in the etiopathogenesis of bronchopulmonary dysplasia (BPD). The aim of this study was to evaluate the preventive effect of Chrysin (CH), an antioxidant, antiinflammatory, antiapoptotic and antifibrotic drug, on hyperoxia-induced lung injury in a neonatal rat model.

METHODS

Forty infant rats were divided into four groups labeled the Control, CH, BPD, and BPD + CH. The control and CH groups were kept in a normal room environment, while the BPD and BPD + CH groups were kept in a hyperoxic (90-95%) environment. At the end of the study, lung tissue was evaluated with respect to apoptosis, histopathological damage and alveolar macrophage score as well as oxidant capacity, antioxidant capacity, and inflammation.

RESULTS

Compared to the BPD + CH and control groups, the lung tissues of the BPD group displayed substantially higher levels of MDA, TOS, TNF-α, and IL-1β (p < 0.05). While the BPD + CH group showed similar levels of TNF-α and IL-1β as the control group, MDA and TOS levels were higher than the control group, and significantly lower than the BPD group (p < 0.05). The BPD group exhibited considerably lower levels of TAS, SOD, GSH, and GSH-Px in comparison to the control group (p < 0.05). The BPD and BPD + CH groups exhibited higher mean scores of histopathological damage and alveolar macrophage when compared to the control and CH groups (p ≤ 0.0001). Both scores were found to be lower in the BPD + CH group in comparison to the BPD group (p ≤ 0.0001). The BPD + CH group demonstrated a significantly lower average of TUNEL and caspase-3 positive cells than the BPD group.

CONCLUSION

We found that prophylaxis with CH results in lower histopathological damage score and reduces apoptotic cell count, inflammation and oxidative stress while increasing anti-oxidant capacity.

Investigation of Apoptotic and Inflammatory Activity in Liver Tissue of Rats Fed with Clam (Pecten maximus, Linnaeus 1758)

One of the most important threats for living things in aquatic ecosystems is environmental pollution. The changes in water quality caused by environmental pollution also reduce the quality of life for organisms in the environment. Among these, the crustaceans which are most affected by the negative changes of environment, fed by the filtration method, are seen as pollution indicator. The consumption of these creatures reaches all steps of the pyramid, especially humans, through the food chain. People who frequently use seafood in their diets may be affected by these negative changes. Heavy metal contents of the clams obtained from Dardanelles were determined by the ICPOES. Twenty-four female Wistar albino rats were fed for 30 days with the experimental diet using clams (Pecten maximus), which was dried and formed into pellets and added to the food in certain proportions. At the end of the study, the subjects were sacrificed under anesthesia, liver tissues were taken, and histochemical examination was performed. TUNEL method was performed to detect apoptotic activity, and immunohistochemical staining with TNF-α and NF-κB antibodies to determine inflammation. Concluding from the results, it was observed that the degeneration of vital digestive system tissues such as liver was inevitable in living creatures that frequently consume seafood obtained from unhealthy environment in their daily diets. The high analysis values of the heavy metal (P. maximus) in food additive can be considered as a reason for histopathological results.

Melatonin attenuates branch chain fatty acid induced apoptosis mediated neurodegeneration

Valproic acid (VPA)-a short branched chain fatty acid (BCFA), is widely recognized as an anticonvulsant and a mood-stabilizing drug, but various adverse effects of VPA have also been investigated. However, the impact of BCFAs aggregation on brain cells, in the pathogenesis of neurodegeneration remains elusive. The objective of this study is to understand the cellular mechanisms underlying VPA-induced neuronal cell death mediated by oxidative stress, and the neuroprotective role of exogenous melatonin treatment on VPA-induced cell death. Neurotoxicity of VPA and protective role exerted by melatonin were assessed in vitro in SH-SY5Y cells and in vivo in the cerebral cortex and cerebellum regions of Wistar rat brain. The results show that melatonin pre-treatment protects the cells from VPA-induced toxicity by exerting an anti-apoptotic and anti-inflammatory effect by regulating apoptotic proteins and pro-inflammatory cytokines. The findings of the present study emphasize novel insights of melatonin as a supplement for the prevention and treatment of neuronal dysfunction induced by VPA.

Evaluation of the modulation of nitric oxide synthase expression in the cerebellum of diabetic albino rats and the possible protective effect of ferulic acid

INTRODUCTION

Diabetes mellitus is a multisystem disease. Oxidative stress and nitric oxide isoforms are involved in diabetic pathogenesis. Ferulic acid is a natural substance that is distributed broadly in plants with strong potent properties.

THE AIM OF THE RESEARCH

This research was designed to study the possible protective role of ferulic acid on oxidative stress and different Nitric oxide synthase isoforms (NOS) in the cerebellum of streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

Twenty-four albino male rats were randomly divided into equal four groups: control group, group 2 received ferulic acid orally (10 mg/kg), group 3 diabetic group, group 4 diabetic rats received ferulic acid. After 8 weeks, the left cerebellar hemisphere was taken for tissue homogenate for oxidative markers and real-time PCR for NOS isoforms. Paraffin sections of the right cerebellar hemisphere were stained with cresyl violet, Luxol fast blue and immnunohistochemically stained for neuronal NOS, inducible NOS and endothelial NOS.

RESULTS

Degenerative changes were seen in the cerebella of the diabetic rats with significant elevation of Malondialdehyde, Nitric Oxide, and decrease of Superoxide dismutase levels. nNOS expression decreased and iNOS expression increased significantly. The ferulic acid-treated group showed a reduction of the degenerative changes in the cerebellum with significant improvement in oxidative stress marker, an increase of nNOS expression, and a decrease of iNOS expression.

CONCLUSIONS

Ferulic acid improves cerebellar functional and histopathological changes induced by diabetes which can be attributed mainly to its anti-oxidative effect and its ability to modulate NOS isoforms.

Melatonin reverses cognitive deficits in streptozotocin-induced type 1 diabetes in the rat through attenuation of oxidative stress and inflammation

Uncontrolled diabetes mellitus (DM) is linked to attentional deficits and cognition deterioration. The neurohormone melatonin is an endogenous synchronizer of circadian rhythms with multiple protective properties. This research was designed to assess its effect against learning and memory decline in streptozotocin (STZ)-induced diabetic rats. Rats were assigned to control, melatonin-treated control, diabetic, and melatonin-treated diabetic groups. Melatonin was administered i.p. at a dose of 10 mg/kg/day for 47 days. Treatment of diabetic rats with melatonin reversed decline of spatial recognition memory in Y maze, performance of rats in novel object discrimination, and retention and recall in passive avoidance tasks. Furthermore, melatonin appropriately attenuated hippocampal malondialdehyde (MDA) and reactive oxygen species (ROS) and improved superoxide dismutase (SOD) activity and improved mitochondrial membrane potential (MMP) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) with no significant effect on nitrite, glutathione (GSH) and catalase activity. Besides, hippocampal level of acetylcholinesterase (AChE), glial fibrillary acidic protein (GFAP), nuclear factor-kappaB (NF-κB), interleukin 6 (IL-6) and tumor necrosis factor α (TNFα) decreased following melatonin treatment. There was also a reduction of dendritic spines of pyramidal neurons of hippocampal CA1 area in diabetic group that was significantly alleviated upon melatonin treatment. Melatonin could ameliorate learning and memory disturbances in diabetic rats through mitigation of cholinesterase activity, astrocytes, oxidative stress and inflammation and also via upregulation of some antioxidants in addition to its prevention of dendritic spine loss.

Melatonin suppresses the brain injury after cerebral ischemia/reperfusion in hyperglycaemic rats

Background and purpose

Diabetes mellitus is a disorder accompanied by oxidative and inflammatory responses, that might exacerbate vascular complications. The purpose of this study was to investigate the potential antioxidant and anti-inflammatory effects of melatonin (MLN) on streptozotocin (STZ)-induced diabetic rats subjected to middle cerebral artery occlusion followed by reperfusion (MCAO/Re).

Experimental approach

Diabetes was induced in rats by a single injection of STZ (55 mg/kg; i.p.). The cerebral injury was then induced by MCAO/Re after six weeks. After 24 h of MCAO/Re the MLN (10 mg/kg) was administered orally for 14 days. Serum and tissue samples were extracted to determine malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), interleukin-1β (IL-1β), and the tumor necrosis factor- α (TNF-α). Part of the brain tissue was kept in formalin for pathological and immunohistochemical studies to determine nuclear factor kappa B (NF-kB) and cyclooxygenase-2 (COX-2) immune reactivity.

Findings/Results

MCAO/Re in STZ-induced hyperglycaemic rats caused a decrease in brain GSH, an increase in brain MDA, and NO was increased in both serum and brain tissue. Rats showed a prominent increase in the serum and brain inflammatory markers viz. IL-1β and TNF-α. Oral treatment with MLN (10 mg/kg) for two weeks reduced the brain levels of MDA, NO, IL-1β, and TNF-α. Impressive amelioration in pathological findings, as well as a significant decrease in NF-kB and COX2 immune stained cells of the cerebral cortex, hippocampus, and cerebellum, occurred after treatment with MLN. It also succeeded to suppress the exacerbation of damage in the brain of hyperglycaemic rats.

Conclusion and implications

Daily intake of MLN attenuates the exacerbation of cerebral ischemic injury in a diabetic state.

Melatonin inhibits high glucose-induced ox-LDL/LDL expression and apoptosis in human umbilical endothelial cells

BACKGROUND

Cardiovascular disease (CVD) is one of the major cause of mortality in diabetic patients. Evidence suggests that hyperglycemia in diabetic patients contributes to increased risk of CVD. This study is to investigate the therapeutic effects of melatonin on glucose-treated human umbilical vein endothelial cells (HUVEC) and provide insights on the underlying mechanisms.

MATERIALS AND METHODS

Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Reactive oxygen species (ROS) and membrane potential was detected using 2',7'-dichlorofluorescein diacetate and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide (JC-1) dye staining, respectively. While, cell apoptosis was determined by Annexin-V staining and protein expression was measured using Western blot.

RESULTS

Our results suggested that melatonin inhibited glucose-induced ROS elevation, mitochondria dysfunction and apoptosis on HUVEC. Melatonin inhibited glucose-induced HUVEC apoptosis via PI3K/Akt signaling pathway. Activation of Akt further activated BcL-2 pathway through upregulation of Mcl-1 expression and downregulation Bax expression in order to inhibit glucose-induced HUVEC apoptosis. Besides that, melatonin promoted downregulation of oxLDL/LOX-1 in order to inhibit glucose-induced HUVEC apoptosis.

CONCLUSIONS

In conclusion, our results suggested that melatonin exerted vasculoprotective effects against glucose-induced apoptosis in HUVEC through PI3K/Akt, Bcl-2 and oxLDL/LOX-1 signaling pathways.

Melatonin: new insights on its therapeutic properties in diabetic complications

Diabetes and diabetic complications are considered as leading causes of both morbidity and mortality in the world. Unfortunately, routine medical treatments used for affected patients possess undesirable side effects, including kidney and liver damages as well as gastrointestinal adverse reactions. Therefore, exploring the novel therapeutic strategies for diabetic patients is a crucial issue. It has been recently shown that melatonin, as main product of the pineal gland, despite its various pharmacological features including anticancer, anti-aging, antioxidant and anti-inflammatory effects, exerts anti-diabetic properties through regulating various cellular mechanisms. The aim of the present review is to describe potential roles of melatonin in the treatment of diabetes and its complications.

Efficacy of melatonin in restoring the antioxidant status in the lens of diabetic rats induced by streptozotocin

Background

Melatonin is a well-known free radical scavenger. The present study aimed to investigate the effects of melatonin treatment on the antioxidant status in the lenticular tissue of streptozotocin (STZ)-induced diabetic rats.

Methods

Thirty-four male rats were randomly divided into four groups as follows: healthy control rats (group 1, n = 10); diabetic control rats (group 2, n = 10); melatonin-treated (5 mg/kg·day) diabetic rats (group 3, n = 10) and melatonin-treated (5 mg/kg·day) healthy rats (group 4, n = 4). Diabetes was induced by injection of streptozotocin (50 mg/kg, ip). Following 8-weeks of melatonin treatment, all rats were killed and the blood plasma and their lenses were stored at -70 °C for antioxidant enzyme activities assay and biochemical determination.

Results

The plasma glucose and lens malondialdehyde (MDA) increased significantly in the rats of group 2 as compared to the group 1. Also, a significant decrease in the levels of catalase (CAT) and glutathione reductase (GR) activities in the lenses and plasma reduced glutathione (GSH) was found. However, the levels of lenticular MDA (not significant) and the plasma glucose significantly decreased in the rats of group 3 compared to the group 2. Besides, the levels of CAT, GR in the rats lens and plasma GSH increased significantly.

Conclusion

Diabetes mellitus induced hyperglycemia and oxidative stress, whereas melatonin decreased the blood glucose levels and lipid peroxidation and increased the activities of antioxidant enzymes in diabetic rat lenses.

Controlled ozone therapy modulates the neurodegenerative changes in the frontal cortex of the aged albino rat

Aging is a normal process associated with neurodegenerative changes resulting in decline of cognitive and motor functions. Oxidative stress plays an important role. Controlled ozone (O₃) therapy has been proved to induce oxidative preconditioning thus reversing oxidative stress. To the best of our knowledge, this research is the first attempt to investigate whether the antioxidant properties of O₃ can ameliorate age-associated structural alterations of the cerebral cortex. Ozone administration (at a dose of 0.7mg/kg intraperitonially, three times a week for eight weeks) produced significant downregulation of tissue malondialdehyde (MDA) and upregulation of glutathione, superoxide dismutase (SOD) and catalase (CAT) within the frontal cortex of aged rats. Sections of the frontal cortex from adult and aged rats were stained with hematoxylin and eosin and analyzed using light microscopy. In addition, quantitative immunohistochemical assessments of the expression of inducible nitric oxide synthase (iNOS), caspase-3, glial fibrillary acidic protein (GFAP), Ki67 and acetylcholinesterase (AChE) were performed. Our results revealed the beneficial effect of O₃ in improving the neurodegenerative changes of the cerebral cortex of aged rats. Moreover, this study clarified that O₃ exerted its effects via reducing oxidative stress, apoptosis, gliosis as well as improving neurogenesis and cholinergic plasticity. This work added to the previously proved aging - associated neurodegenerative effects and provided a new insight into the promising role of O₃ to ameliorate these effects.

Histological investigations on thymus of male rats prenatally exposed to bisphenol A

Bisphenol A is called as a endocrine-distrupting chemical because of the its steroid-like activity and it used in the construction of plastic containing materials. It is indicated that bisphenol A can pass the human serum, urine, follicular fluid, placenta and umblical cord as a result of the use of substances containing this agent. In this study, we aimed to investigate the effects of bisphenol A on the development of the thymus, a primary lymphoid organ which plays an important role in the specific immunity. The adult pregnant female rats were administered orally with bisphenol A (for 21 days) and postnatal thymus samples were obtained on day 21, 45 and 90 and were performed for histochemical and immunohistochemical staining for CD3, CD4, CD8 and CD79a and TUNEL assay for the apoptotic cells. Evaluation of all groups, CD3, CD4, CD8 and CD79a stainings were decreased in the experimental groups compared with control group. The apoptotic cells were determined in the all groups on day 90 as a result of the thymus involution. It is noted that there was not any histological and morphological damages in the rats prenatally exposed the bisphenol A. The effect of the bisphenol A is unknown in the future, but there is no problem in the adult rats.

Neuroprotective effect of Cucumis melo Var. flexuosus leaf extract on the brains of rats with streptozotocin-induced diabetes

The central nervous system is one of the most vulnerable organs affected by the oxidative stress associated with diabetes mellitus. Healthy food provides an important source for antioxidants. Therefore, the protective effect of Cucumis melo var. flexuosus (C. melo var. flexuosus) leaf extract on the brains of diabetic rats was investigated. Adult male albino rats divided into 5 groups of 6 rats each were assigned into a normal control group and four diabetic groups. Diabetes was induced in rats by a single intraperitoneal injection of streptozotocin (STZ; 60 mg/kg bw). One of the four diabetic groups was left untreated and was considered as a diabetic control group while the three other groups were treated with C. melo var. flexuosus leaf extract at the doses of 30, 60 and 120 mg/kg bw for a period of 30 days. After completion of experimental duration plasma and brains were used for evaluating biochemical changes. The obtained data showed that C. melo var. flexuosus leaf extract treatment lowered blood glucose, glycated hemoglobin, brain tumor necrosis factor-alpha, interleukin levels, brain malondialdehyde content and caspase-3 activity. Furthermore, the treatment resulted in a marked increase in plasma dopamine, melatonin, brain vascular endothelial growth factor-A levels, brain catalase and superoxide dismutase activities. From the present study, it can be concluded that the C. melo var. flexuosus leaf extract exerts a neuroprotective effect against oxidative damage associated with diabetes.

Protective Effects of Melatonin on Retinal Inflammation and Oxidative Stress in Experimental Diabetic Retinopathy

Oxidative stress and inflammation are important pathogenic factors contributing to the etiology of diabetic retinopathy (DR). Melatonin is an endogenous hormone that exhibits a variety of biological effects including antioxidant and anti-inflammatory functions. The goals of this study were to determine whether melatonin could ameliorate retinal injury and to explore the potential mechanisms. Diabetes was induced by a single intraperitoneal (i.p.) injection of STZ (60 mg/kg) in Sprague-Dawley rats. Melatonin (10 mg kg(-1) daily, i.p.) was administered from the induction of diabetes and continued for up to 12 weeks, after which the animals were sacrificed and retinal samples were collected. The retina of diabetic rats showed depletion of glutathione and downregulation of glutamate cysteine ligase (GCL). Melatonin significantly upregulated GCL by retaining Nrf2 in the nucleus and stimulating Akt phosphorylation. The production of proinflammatory cytokines and proteins, including interleukin 1β, TNF-α, and inducible nitric oxide synthase (iNOS), was inhibited by melatonin through the NF-κB pathway. At 12 weeks, melatonin prevented the significant decrease in the ERG a- and b-wave amplitudes under the diabetic condition. Our results suggest potent protective functions of melatonin in diabetic retinopathy. In addition to being a direct antioxidant, melatonin can exert receptor-mediated signaling effects to attenuate inflammation and oxidative stress of the retina.

Genetic and Histopathological Responses to Cadmium Toxicity in Rabbit's Kidney and Liver: Protection by Ginger (Zingiber officinale)

This study aimed to examine the protective effects of ginger (G) on the genetic response induced by cadmium (Cd) and immunohistochemical expression of Caspase3 and MKI67 in the kidney and liver of rabbits. Male rabbits were divided into three groups; each group contains 10 animals: group (C) received basic diet and tap water for 12 weeks, the second group (Cd) received 200 mg/kg b.w CdCl2 in water for 12 weeks, group (Cd + G) was given 200 mg/kg b.w CdCl2 in water and 400 mg ginger/kg b.w in food for 12 weeks. Cd administration increased the activity of mRNA expression of the examined apoptotic (Caspase3), proliferation (MKI67), proto-oncogene (C-fos), and antioxidant (GST), while decreased the expression of anti-apoptotic (Bcl2). Ginger counteracted the effects of Cd in (Cd + G) group and downregulated the previously upregulated genes under Cd administration appeared in (Cd) group. The immunohistochemical expression of Caspase3 and MKI67 in the liver and kidney cells of the (C) group was shown very faint to negative reactions, strong staining in hepatocytes and the tubular epithelium in cadmium-treated group, while slight staining in some hepatocytes and tubular epithelium in co-administration with ginger in (Cd + G) group. In conclusion, ginger administration showed a protective effect against cadmium toxicity.

Protecting the BBB endothelium against cigarette smoke-induced oxidative stress using popular antioxidants: Are they really beneficial?

Blood Brain Barrier (BBB) exposed to realistic concentrations (comparable to a chronic heavy smoker) of Cigarette Smoke Extract (CSE) triggers a strong endothelial inflammatory response which can lead to the onset of neurological disorders. The involvement of Reactive Oxygen Species (ROS) in this inflammatory cascade is evident from the up-regulation of nuclear factor erythroid 2 related factor 2 (Nrf-2), a transcription factor involved in anti-oxidant response signaling in CSE exposed endothelial cells. We have shown that pre-treatment with α-tocopherol and/or ascorbic acid is highly protective for the BBB, thus suggesting that, prophylactic administration of antioxidants can reduce CSE and/or inflammatory-dependent BBB damage. We have assessed and ranked the protective effects of 5 popular OTC antioxidants (Coenzyme Q10, melatonin, glutathione, lipoic acid and resveratrol) against CSE-induced BBB endothelial damage using hCMEC/D3 cells. The analysis of pro-inflammatory cytokines release by ELISA revealed that resveratrol, lipoic acid melatonin and Co-Q10 inhibited the BBB endothelial release of pro-inflammatory cytokines IL-6 and IL-8, reduced (not Co-Q10) CSE-induced up-regulation of Platelet Cell Adhesion Molecule-1 (PECAM-1), Vascular Cell Adhesion Molecule-1 (VCAM-1) & E-selectin and inhibited monocytes-endothelial cell adhesion. The anti-inflammatory effects correlated with the anti-oxidative protection endowed by these compounds as evidenced by upregulation of NADPH: Quinone Oxidoreductase 1 (NQO1) and reduced cellular oxidative stress. CSE-induced release of Vascular Endothelial Growth Factor (VEGF) was inhibited by all tested compounds although the effect was not strictly dose-dependent. Further in vivo studies are required to validate our results and expand our current study to include combinatorial treatments.

Effects of kolaviron on hepatic oxidative stress in streptozotocin induced diabetes

Background

Alteration in antioxidant defence and increase in oxidative stress that results in tissue injury is characteristic of diabetes. We evaluated the protective effects of kolaviron (a flavonoid complex extracted from the seeds of Garcinia kola) on hepatic antioxidants, lipid peroxidation and apoptosis in diabetic rats.

Methods

To induce diabetes, rats were injected with streptozotocin intraperitoneally at a single dose of 50 mg/kg. Kolaviron (100 mg/kg) was administered orally for 6 weeks (5 times weekly). Activities of liver antioxidant enzymes was analysed with Multiskan Spectrum plate reader. High performance liquid chromatography (HPLC) was used in the analysis of MDA (malondialdehyde), a product of lipid peroxidation. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay.

Result

Diabetic rats exhibited a significant increase in the peroxidation of hepatic lipids as observed from the elevated level of malondialdehyde (MDA). In addition, Oxygen Radical Absorbance Capacity (ORAC), level of reduced glutathione (GSH), ratio of reduced to oxidized glutathione (GSH: GSSG) and catalase (CAT) activity were decreased in the liver of diabetic rats. The activities of GPX (glutathione peroxidase) and SOD (superoxide dismutase) were unaltered in diabetic rats. TUNEL assay revealed increased apoptotic cell death in the liver. Kolaviron attenuated lipid peroxidation and apoptosis, increased CAT activity, GSH levels and GSH: GSSG ratio. The ORAC of kolaviron-treated diabetic liver was restored to near-normal values.

Conclusion

Kolaviron protects the liver against oxidative and apoptotic damage induced by hyperglycemia.

Neurotoxic effects of local anesthetics on the mouse neuroblastoma NB2a cell line

Local anesthetics are used clinically for peripheral nerve blocks, epidural anesthesia, spinal anesthesia and pain management; large concentrations, continuous application and long exposure time can cause neurotoxicity. The mechanism of neurotoxicity caused by local anesthetics is unclear. Neurite outgrowth and apoptosis can be used to evaluate neurotoxic effects. Mouse neuroblastoma cells were induced to differentiate and generate neurites in the presence of local anesthetics. The culture medium was removed and replaced with serum-free medium plus 20 μl combinations of epidermal growth factor and fibroblast growth factor containing tetracaine, prilocaine, lidocaine or procaine at concentrations of 1, 10, 25, or 100 μl prior to neurite measurement. Cell viability, iNOS, eNOS and apoptosis were evaluated. Local anesthetics produced toxic effects by neurite inhibition at low concentrations and by apoptosis at high concentrations. There was an inverse relation between local anesthetic concentrations and cell viability. Comparison of different local anesthetics showed toxicity, as assessed by cell viability and apoptotic potency, in the following order: tetracaine > prilocaine > lidocaine > procaine. Procaine was the least neurotoxic local anesthetic and because it is short-acting, may be preferred for pain prevention during short procedures.

Neuroprotective effect of ginger in the brain of streptozotocin-induced diabetic rats

Diabetes mellitus results in neuronal damage caused by increased intracellular glucose leading to oxidative stress. Recent evidence revealed the potential of ginger for reducing diabetes-induced oxidative stress markers. The aim of this study is to investigate, for the first time, whether the antioxidant properties of ginger has beneficial effects on the structural brain damage associated with diabetes. We investigated the observable neurodegenerative changes in the frontal cortex, dentate gyrus, and cerebellum after 4, 6, and 8 weeks of streptozotocin (STZ)-induced diabetes in rats and the effect(s) of ginger (500 mg/kg/day). Sections of frontal cortex, dentate gyrus, and cerebellum were stained with hematoxylin and eosin and examined using light microscopy. In addition, quantitative immunohistochemical assessments of the expression of inducible NO synthase (iNOS), tumor necrosis factor (TNF)-α, caspase-3, glial fibrillary acidic protein (GFAP), acetylcholinesterase (AChE), and Ki67 were performed. Our results revealed a protective role of ginger on the diabetic brain via reducing oxidative stress, apoptosis, and inflammation. In addition, this study revealed that the beneficial effect of ginger was also mediated by modulating the astroglial response to the injury, reducing AChE expression, and improving neurogenesis. These results represent a new insight into the beneficial effects of ginger on the structural alterations of diabetic brain and suggest that ginger might be a potential therapeutic strategy for the treatment of diabetic-induced damage in brain.

Melatonin attenuates isoflurane-induced acute memory impairments in aged rats

Melatonin is an endogenous hormone with neuroprotective effects. Melatonin levels in elderly patients are reduced after surgeries that require anaesthesia. Whether reduced melatonin levels are important for postoperative cognitive dysfunction (POCD) remains unclear. Here, we investigated the effects of melatonin on cognitive dysfunctions induced by isoflurane and mechanisms underlying these effects. Seventy-two 20-month-old Sprague-Dawley rats were randomly divided into six groups (n = 12). These groups included M1 and M10 groups that received intraperitoneal melatonin at 1 mg/kg or 10 mg/kg, respectively, and an ISO group that received 4 hr of inhaled 2% isoflurane. They also included M1+ISO and M10+ISO groups that received 1 mg/kg or 10 mg/kg of melatonin plus 4 hr of inhaled 2% isoflurane, respectively, and a control group that received an equal volume of saline. Injections were administered daily for 14 consecutive days. Memory was assessed in the Morris water maze. Plasma and hippocampi were harvested to determine melatonin concentrations and MT1/MT2 receptor expression. Rats treated only with isoflurane showed significantly longer latencies in Morris water maze test trials compared with the control group, with shorter time in the probe trial (p < 0.05). Although plasma melatonin levels and MT2 expression in the hippocampus were significantly decreased, MT1 expression was higher in the isoflurane group than in the control group (p < 0.001). However, these parameters did not significantly vary in animals administered melatonin compared with controls. Isoflurane may induce cognitive dysfunction by influencing melatonin and MT1/MT2 levels. Melatonin can improve cognitive dysfunction by normalizing plasma melatonin and its receptor levels.

Therapeutic efficacy of melatonin in reducing retinal damage in an experimental model of early type 2 diabetes in rats

Diabetic retinopathy (DR) is a leading cause of acquired blindness in adults, mostly affected by type 2 diabetes mellitus (T2DM). We have developed an experimental model of early T2DM in adult rats which mimics some features of human T2DM at its initial stages and provokes significant retinal alterations. The aim of this work was to analyze the effect of melatonin on retinal changes induced by the moderate metabolic derangement. For this purpose, adult male Wistar rats received a control diet or 30% sucrose in the drinking water. Three weeks after this treatment, animals were injected with vehicle or streptozotocin (STZ, 25 mg/kg). One day or 3 wk after vehicle or STZ injection, animals were subcutaneously implanted with a pellet of melatonin. Fasting and postprandial glycemia, and glucose, and insulin tolerance tests were analyzed. At 12 wk of treatment, animals which received a sucrose-enriched diet and STZ showed significant differences in metabolic tests, as compared with control groups. Melatonin, which did not affect glucose metabolism in control or diabetic rats, prevented the decrease in the electroretinogram a-wave, b-wave, and oscillatory potential amplitude, and the increase in retinal lipid peroxidation, NOS activity, TNFα, Müller cells glial fibrillary acidic protein, and vascular endothelial growth factor levels. In addition, melatonin prevented the decrease in retinal catalase activity. These results indicate that melatonin protected the retina from the alterations observed in an experimental model of DR associated with type 2 diabetes.