Hyperglycemia-induced alterations in synaptosomal membrane fluidity and activity of membrane bound enzymes: beneficial effect of N-acetylcysteine supplementation

Associations Between Diabetes Mellitus and Neurodegenerative Diseases

Diabetes mellitus (DM) and neurodegenerative diseases/disturbances are worldwide health problems. The most common chronic conditions diagnosed in persons 60 years and older are type 2 diabetes mellitus (T2DM) and cognitive impairment. It was found that diabetes mellitus is a major risk for cognitive decline, dementia, Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS) and other neurodegenerative disorders. Different mechanisms of associations between these diseases and diabetes mellitus have been suggested. For example, it is postulated that an impaired intracellular insulin signaling pathway, together with hyperglycemia and hyperinsulinemia, may cause pathological changes, such as dysfunction of the mitochondria, oxidative stress inflammatory responses, etc. The association between diabetes mellitus and neurodegenerative diseases, as well as the mechanisms of these associations, needs further investigation. The aim of this review is to describe the associations between diabetes mellitus, especially type 1 (T1DM) and type 2 diabetes mellitus, and selected neurodegenerative diseases, i.e., Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. Suggested mechanisms of these associations are also described.

Proteolethargy is a pathogenic mechanism in chronic disease

The pathogenic mechanisms of many diseases are well understood at the molecular level, but there are prevalent syndromes associated with pathogenic signaling, such as diabetes and chronic inflammation, where our understanding is more limited. Here, we report that pathogenic signaling suppresses the mobility of a spectrum of proteins that play essential roles in cellular functions known to be dysregulated in these chronic diseases. The reduced protein mobility, which we call proteolethargy, was linked to cysteine residues in the affected proteins and signaling-related increases in excess reactive oxygen species. Diverse pathogenic stimuli, including hyperglycemia, dyslipidemia, and inflammation, produce similar reduced protein mobility phenotypes. We propose that proteolethargy is an overlooked cellular mechanism that may account for various pathogenic features of diverse chronic diseases.

Diabetes mellitus and Alzheimer's disease: Understanding disease mechanisms, their correlation, and promising dual activity of selected herbs

ETHNOPHARMACOLOGICAL RELEVANCE

This review explores the link between Type 2 Diabetes Mellitus (T2DM) and diabetes-induced Alzheimer's disease (AD). It emphasizes the shared pathophysiological links and mechanisms between the two conditions, focusing on reduced insulin levels and receptors, impaired glucose metabolism, insulin resistance, mitochondrial dysfunction, and oxidative damage in AD-affected brains-paralleling aspects of T2DM. The review suggests AD as a "diabetes of the brain," supported by cognitive enhancement through antidiabetic interventions. It focuses on the traditionally used Indian herbs as a means to manage both conditions while addressing developmental challenges.

AIM OF THE STUDY

This study explores the DM-AD connection, reviewing medicinal herbs with protective potential for both ailments, considering traditional uses and developmental challenges.

MATERIALS AND METHODS

Studied research, reviews, and ethnobotanical and scientific data from electronic databases and traditional books.

RESULTS

The study analyzes the pathophysiological links between DM and AD, emphasizing their interconnected factors. Eight Ayurvedic plants with dual protective effects against T2DM and AD are thoroughly reviewed with preclinical/clinical evidence. Historical context, phytoconstituents, and traditional applications are explored. Innovative formulations using these plants are examined. Challenges stemming from phytoconstituents' physicochemical properties are highlighted, prompting novel formulation development, including nanotechnology-based delivery systems. The study uncovers obstacles in formulating treatments for these diseases.

CONCLUSION

The review showcases the dual potential of chosen medicinal herbs against both diseases, along with their traditional applications, endorsing their use. It addresses formulation obstacles, proposing innovative delivery technologies for herbal therapies, while acknowledging their constraints. The review suggests the need for heightened investment and research in this area.

Anesthetic Mechanisms: Synergistic Interactions With Lipid Rafts and Voltage-Gated Sodium Channels

Despite successfully utilizing anesthetics for over 150 years, the mechanism of action remains relatively unknown. Recent studies have shown promising results, but due to the complex interactions between anesthetics and their targets, there remains a clear need for further mechanistic research. We know that lipophilicity is directly connected to anesthetic potency since lipid solubility relates to anesthetic partition into the membrane. However, clinically relevant concentrations of anesthetics do not significantly affect lipid bilayers but continue to influence various molecular targets. Lipid rafts are derived from liquid-ordered phases of the plasma membrane that contain increased concentrations of cholesterol and sphingomyelin and act as staging platforms for membrane proteins, including ion channels. Although anesthetics do not perturb membranes at clinically relevant concentrations, they have recently been shown to target lipid rafts. In this review, we summarize current research on how different types of anesthetics-local, inhalational, and intravenous-bind and affect both lipid rafts and voltage-gated sodium channels, one of their major targets, and how those effects synergize to cause anesthesia and analgesia. Local anesthetics block voltage-gated sodium channel pores while also disrupting lipid packing in ordered membranes. Inhalational anesthetics bind to the channel pore and the voltage-sensing domain while causing an increase in the number, size, and diameter of lipid rafts. Intravenous anesthetics bind to the channel primarily at the voltage-sensing domain and the selectivity filter, while causing lipid raft perturbation. These changes in lipid nanodomain structure possibly give proteins access to substrates that have translocated as a result of these structural alterations, resulting in lipid-driven anesthesia. Overall, anesthetics can impact channel activity either through direct interaction with the channel, indirectly through the lipid raft, or both. Together, these result in decreased sodium ion flux into the cell, disrupting action potentials and producing anesthetic effects. However, more research is needed to elucidate the indirect mechanisms associated with channel disruption through the lipid raft, as not much is known about anionic lipid products and their influence over voltage-gated sodium channels. Anesthetics' effect on S-palmitoylation, a promising mechanism for direct and indirect influence over voltage-gated sodium channels, is another auspicious avenue of research. Understanding the mechanisms of different types of anesthetics will allow anesthesiologists greater flexibility and more specificity when treating patients.

Further learning of clinical characteristics and imaging manifestations of nonketotic hyperglycemic hemichorea

OBJECTIVE

To summarize the clinical characteristics and imaging manifestations of patients with nonketotic hyperglycemic hemichorea (NH-HC) and to explore the possible pathogenesis, diagnosis. and treatment of the disease in order to improve the understanding of this disease and avoid misdiagnosis.

METHODS

Retrospective analysis was performed on the case data of five patients with NH-HC admitted to our hospital in recent years. The patients were treated in the department of endocrinology, department of neurology, and department of neurosurgery in our hospital, respectively. Meanwhile, relevant literatures were consulted for further learning.

RESULTS

NH-HC is usually presented as a triad of nonketotic hyperglycemia, lateral chorea, and typical imaging manifestations of head magnetic resonance imaging or computed tomography, but the clinical manifestations are not the same, and imaging features may also be different, presenting a diversified trend in clinical practice. All five patients were given glucose-lowering drugs and improved with or without combination of drugs to control symptoms of chorea.

CONCLUSION

NH-HC is a rare complication of diabetes, characterized by hyperglycemia and hemichorea. How to identify the extreme situation and make fast judgment is a top priority. Timely and correct control of blood glucose is the key to the treatment, and when necessary, application of dopamine receptor antagonists in patients with combination therapy can accelerate improvement of the clinical symptoms. The prognosis of NH-HC is good, the clinician should strengthen comprehensive understanding of this disease to avoid missed diagnosis or misdiagnosis and enable patients to get more timely and effective treatment.

Garlic (Allium sativum L.) in diabetes and its complications: Recent advances in mechanisms of action

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia and impaired islet secretion that places a heavy burden on the global health care system due to its high incidence rate, long disease course and many complications. Fortunately, garlic (Allium sativum L.), a well-known medicinal plant and functional food without the toxicity and side effects of conventional drugs, has shown positive effects in the treatment of diabetes and its complications. With interdisciplinary development and in-depth exploration, we offer a clear and comprehensive summary of the research from the past ten years, focusing on the mechanisms and development processes of garlic in the treatment of diabetes and its complications, aiming to provide a new perspective for the treatment of diabetes and promote the efficient development of this field.

Cationic Solid Lipid Nanoparticles of Resveratrol for Hepatocellular Carcinoma Treatment: Systematic Optimization, in vitro Characterization and Preclinical Investigation

Aim

The present study focuses on the development and evaluation of the resveratrol (RV)-loaded cationic solid lipid nanoparticles (RV-c-SLNs) for the management of hepatocellular carcinoma (HCC).

Materials and Methods

Optimization of formulation was performed using factorial design, and further in vitro drug release, cytotoxicity, biodistribution, in vivo preclinical, and biochemical evaluation were carried out.

Results

The optimized formulation exhibited uniform size, homogeneous disparity, positive zeta potential, and stability over 12-week storage at 25°C/60% RH. The in vitro drug release and cytotoxicity study showed 60% drug release within the first 6 hours and comparatively higher cytotoxicity on HepG2 cell line by resveratrol-solid lipid nanoparticle (RV-SLN) as compared to the RV solution. In addition, an anticancer action and biodistribution study on a rat model of HCC showed significant reduction of tumor volume and higher accumulation in the tumor tissue from RV-c-SLN (P<0.01) over RV solution and RV-SLN. Furthermore, RV-c-SLN showed significant down-regulation in the levels of pro-inflammatory cytokines and balancing of antioxidant enzymes. Histopathological investigation showed reduced occurrence of hepatic nodules, necrosis formation, infiltration of inflammatory cells, blood vessels inflammation, and cell swelling.

Conclusion

Overall, the obtained results construed that RV-c-SLN with improved antitumor activity as clearly evident from in vitro, in vivo, and biochemical investigations.

Effects of compound K, a metabolite of ginsenosides, on memory and cognitive dysfunction in db/db mice involve the inhibition of ER stress and the NLRP3 inflammasome pathway

Accumulating clinical and epidemiological evidence indicates a close relationship between diabetes mellitus and dementia. The ginsenoside compound K (CK) has been reported to ameliorate diabetes mellitus and confer protection to the central nervous system. In this study, we investigated whether CK could improve memory impairment and cognitive dysfunction in diabetic db/db mice. Firstly, we found that CK treatments significantly improved behavioral impairment and cognitive dysfunction based on Morris water maze, Y-maze, and fear conditioning tests. Besides, CK decreased the fasting glucose level, increased lipid metabolism, and ameliorated glucose tolerance, insulin sensitivity, and dyslipidemia in diabetic db/db mice. In addition, CK treatments alleviated oxidative stress and inhibited the inflammatory response in hippocampal tissue. Further investigations showed that CK treatments inhibited the NLRP3 inflammasome pathway, as evidenced by the declined expression of TXNIP, NLRP3 inflammasomes, ASC, cleaved caspase-1, and mature IL-1β in hippocampal tissues. Moreover, CK treatments alleviated ER stress via down-regulating the level of BiP, CHOP, p-PERK, p-IRE1α and ATF6 in the hippocampus of db/db mice. These results suggest that CK improves memory and cognitive dysfunction, possibly by ameliorating glucose tolerance, insulin sensitivity, and dyslipidemia, suppressing oxidative stress and inflammatory response and modulating the NLRP3 inflammasome pathway and ER stress.

Oxidative and Inflammatory Events in Prion Diseases: Can They Be Therapeutic Targets?

Prion diseases are a group of incurable infectious terminal neurodegenerative diseases caused by the aggregated misfolded PrPsc in selected mammals including humans. The complex physical interaction between normal prion protein PrPc and infectious PrPsc causes conformational change from the α- helix structure of PrPc to the β-sheet structure of PrPsc, and this process is repeated. Increased oxidative stress is one of the factors that facilitate the conversion of PrPc to PrPsc. This overview presents evidence to show that increased oxidative stress and inflammation are involved in the progression of this disease. Evidence is given for the participation of redoxsensitive metals Cu and Fe with PrPsc inducing oxidative stress by disturbing the homeostasis of these metals. The fact that some antioxidants block the toxicity of misfolded PrPc peptide supports the role of oxidative stress in prion disease. After exogenous infection in mice, PrPsc enters the follicular dendritic cells where PrPsc replicates before neuroinvasion where they continue to replicate and cause inflammation leading to neurodegeneration. Therefore, reducing levels of oxidative stress and inflammation may decrease the rate of the progression of this disease. It may be an important order to reduce oxidative stress and inflammation at the same time. This may be achieved by increasing the levels of antioxidant enzymes by activating the Nrf2 pathway together with simultaneous administration of dietary and endogenous antioxidants. It is proposed that a mixture of micronutrients could enable these concurrent events thereby reducing the progression of human prion disease.

Folic acid increases levels of GHS in brain of rats with oxidative stress induced with 3-nitropropionic acid

Aim: This study tested the hypothesis that folic acid (FA) modulates biogenic amines and protects the brain against oxidative stress induced by 3-nitropropionic acid (3NPA).Methods: Male Wistar rats received (groups of six) for 5 d: FA (50 mg/kg); 3NPA (10 mg/kg); or FA +3NPA. At last day, rats were sacrificed, and their brain was obtained to measure the levels of dopamine, 5-hydroxiindol acetic acid (5-HIAA). Reduced glutathione (GSH), total ATPase, H₂O₂ and lipid peroxidation were measured.Results: GSH increased significantly in cortex of rats treated with FA. ATPase increased significantly in cerebellum/medulla oblongata and decreased in cortex of animal treated with 3NPA. 5-HIAA increased in striatum of rats that received 3NPA alone or combined with FA.Conclusion: 3NPA generates free radicals such effect can be counteracted with FA administration since this folate increases antioxidant capacity and modulates biogenic amines.

A review on therapeutic potentials of Trigonella foenum graecum (fenugreek) and its chemical constituents in neurological disorders: Complementary roles to its hypolipidemic, hypoglycemic, and antioxidant potential

OBJECTIVES

The growing rate of neurological disorders is a major concern in today's scenario. Today's research is focusing on therapeutic interventions providing benefits in these disorders. Presently, drugs of natural origin have gained more interest for the treatment of central nervous system disorders for their efficacy and less/ no side effects. This review is emphasizing the cited roles of Trigonella foenum graecum (fenugreek) and its constituents in different neurological manifestations.

METHOD

A review of the literature, relevant to the role of fenugreek and its major constituents including saponins and alkaloids in different neurological aspects and in delineating the health benefits, was conducted.

RESULTS

The cited research acknowledged that fenugreek and its constituents exert positive influence on neurological health. Few studies have reported the beneficial role of fenugreek and its constituents like trigonelline in pathological symptoms of Alzheimer's disease. Similarly, other studies evidenced the neuroprotective, antidepressant, antianxiety as well as modulatory effect on cognitive functions and Parkinson's disease.

DISCUSSION

Large populations are the sufferers of the neurological disorders, pointing the need for investigation of such therapeutic interventions which target and delay the underlying pathological hallmarks and exert positive influence on different neurological health problems. Hypolipidemic, hypoglycemic, antioxidant, and immunomodulatory effects of fenugreek and its constituents with their potential role in various neurological disorders were already reported. In future, it would be of even greater interest to further develop more effective dosage, supplementation period, and to evaluate the therapeutic potentials of fenugreek and its constituents in neurological disorders by exploring underlying cellular and molecular mechanisms.

Implication of nano-antioxidant therapy for treatment of hepatocellular carcinoma using PLGA nanoparticles of rutin

Aim: The present work describes the development of poly(lactic co-glycolic acid) (PLGA) nanoparticles (NPs) of rutin (RT) for the treatment of hepatocellular carcinoma in rats. Materials & methods: RT-loaded PLGA NPs (RT-PLGA-NPs) were prepared by double emulsion evaporation method. Further these are optimized by Box–Behnken design. PLGA NPs were evaluated for size, polydispersity index, drug-loading capacity, entrapment, gastric stability, in vitro drug release, in vivo preclinical studies and biochemical studies. Results: Preclinical evaluation of RT-PLGA-NPs for anticancer activity through oral route exhibited significant improvement in hepatic, hematologic and renal biochemical parameters. Highly superior activity was observed in regulating oxidative stress and inflammatory markers, antioxidant enzymes, cytokines and inflammatory mediators and their role on plasma membrane ATPases responsible for destruction in liver tissues. Conclusion: Histopathological evaluation indicated reduced incidence of hepatic nodules, necrosis formation, infiltration of inflammatory cells, blood vessel inflammation and cell swelling with RT-PLGA-NP treatment along with considerable downregulation in the levels of proinflammatory cytokines.

The adiponectin receptor AdipoR2 and its Caenorhabditis elegans homolog PAQR-2 prevent membrane rigidification by exogenous saturated fatty acids

Dietary fatty acids can be incorporated directly into phospholipids. This poses a specific challenge to cellular membranes since their composition, hence properties, could greatly vary with different diets. That vast variations in diets are tolerated therefore implies the existence of regulatory mechanisms that monitor and regulate membrane compositions. Here we show that the adiponectin receptor AdipoR2, and its C. elegans homolog PAQR-2, are essential to counter the membrane rigidifying effects of exogenously provided saturated fatty acids. In particular, we use dietary supplements or mutated E. coli as food, together with direct measurements of membrane fluidity and composition, to show that diets containing a high ratio of saturated to monounsaturated fatty acids cause membrane rigidity and lethality in the paqr-2 mutant. We also show that mammalian cells in which AdipoR2 has been knocked-down by siRNA are unable to prevent the membrane-rigidifying effects of palmitic acid. We conclude that the PAQR-2 and AdipoR2 proteins share an evolutionarily conserved function that maintains membrane fluidity in the presence of exogenous saturated fatty acids.

Streptozotocin produces oxidative stress, inflammation and decreases BDNF concentrations to induce apoptosis of RIN5F cells and type 2 diabetes mellitus in Wistar rats

BACKGROUND

Neurodegenerative disorders, such as deficits in learning, memory and cognition and Alzheimer's disease are associated with diabetes mellitus. Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor and is known to possess anti-obesity, anti-diabetic actions and is believed to have a role in memory and Alzheimer's disease.

OBJECTIVE

To investigate whether STZ can reduce BDNF production by rat insulinoma (RIN5F) cells in vitro and decrease BDNF levels in the pancreas, liver and brain in vivo.

METHODS

Streptozotocin (STZ)-induced cytotoxicity to RIN5F cells in vitro and type 2 DM in Wistar rats was employed in the present study. Cell viability, activities of various anti-oxidants and secretion of BDNF by RIN5F cells in vitro were measured using MTT assay, biochemical methods and ELISA respectively. In STZ-induced type 2 DM rats: plasma glucose, interleukin-6 and tumor necrosis factor-α levels and BDNF protein expression in the pancreas, liver and brain tissues were measured. In addition, neuronal count and morphology in the hippocampus and hypothalamus areas was assessed.

RESULTS

STZ-induced suppression of RIN5F cell viability was abrogated by BDNF. STZ suppressed BDNF secretion by RIN5F cells in vitro. STZ-induced type 2 DM rats showed hyperglycemia, enhanced plasma IL-6 and TNF-αlevels and reduced plasma and pancreas, liver and brain tissues (P < 0.001) and increased oxidative stress compared to untreated control. Hypothalamic and hippocampal neuron in STZ-treated animals showed a decrease in the number of neurons and morphological changes suggesting of STZ cytotoxicity.

CONCLUSIONS

The results of the present study suggest that STZ is not only cytotoxic to pancreatic beta cells but also to hypothalamic and hippocampal neurons by inducing oxidative stress. STZ ability to suppress BDNF production by pancreas, liver and brain tissues suggests that impaired memory, learning, and cognitive dysfunction seen in diabetes mellitus could be due to BDNF deficiency.

Revisiting the membrane-centric view of diabetes

Fundamental questions remain unresolved in diabetes: What is the actual mechanism of glucose toxicity? Why is there insulin resistance in type 2 diabetes? Why do diets rich in sugars or saturated fatty acids increase the risk of developing diabetes? Studying the C. elegans homologs of the anti-diabetic adiponectin receptors (AdipoR1 and AdipoR2) has led us to exciting new discoveries and to revisit what may be termed “The Membrane Theory of Diabetes”. We hypothesize that excess saturated fatty acids (obtained through a diet rich in saturated fats or through conversion of sugars into saturated fats via lipogenesis) leads to rigid cellular membranes that in turn impair insulin signalling, glucose uptake and blood circulation, thus creating a vicious cycle that contributes to the development of overt type 2 diabetes. This hypothesis is supported by our own studies in C. elegans and by a wealth of literature concerning membrane composition in diabetics. The purpose of this review is to survey this literature in the light of the new results, and to provide an admittedly membrane-centric view of diabetes.

Effects of chlorogenic acid, caffeine and coffee on components of the purinergic system of streptozotocin-induced diabetic rats

We evaluated the effect of chlorogenic acid (CGA), caffeine (CA) and coffee (CF) on components of the purinergic system from the cerebral cortex and platelets of streptozotocin-induced diabetic rats. Animals were divided into eight groups: control animals treated with (I) water (WT), (II) CGA (5 mg/kg), (III) CA (15 mg/kg) and (IV) CF (0.5 g/kg), and diabetic animals treated with (V) WT, (VI) CGA (5 mg/kg), (VII) CA (15 mg/kg) and (VIII) CF (0.5 g/kg). Our results showed an increase (173%) in adenosine monophosphate (AMP) hydrolysis in the cerebral cortex of diabetic rats. In addition, CF treatment increased adenosine diphosphate (ADP) and AMP hydrolysis in group VIII synaptosomes. Platelets showed an increase in ectonucleotidase activity in group V, and all treatments reduced the increase in adenosine triphosphate and ADP hydrolysis. Furthermore, there was an increase in platelet aggregation of 72% in the diabetic rats, and CGA and CF treatment reduced platelet aggregation by nearly 60% when compared to diabetic rats. In this context, we can suggest that CGA and CF treatment should be considered a therapeutic and scientific target to be investigated in diseases associated with hyperglycemia.

A 3-methylcrotonyl-CoA carboxylase deficient human skin fibroblast transcriptome reveals underlying mitochondrial dysfunction and oxidative stress

Isolated 3-methylcrotonyl-CoA carboxylase (MCC) deficiency is an autosomal recessive inherited metabolic disease of leucine catabolism with a highly variable phenotype. Apart from extensive mutation analyses of the MCCC1 and MCCC2 genes encoding 3-methylcrotonyl-CoA carboxylase (EC 6.4.1.4), molecular data on MCC deficiency gene expression studies in human tissues is lacking. For IEMs, unbiased '-omics' approaches are starting to reveal the secondary cellular responses to defects in biochemical pathways. Here we present the first whole genome expression profile of immortalized cultured skin fibroblast cells of two clinically affected MCC deficient patients and two healthy individuals generated using Affymetrix(®)HuExST1.0 arrays. There were 16191 significantly differentially expressed transcript IDs of which 3591 were well annotated and present in the predefined knowledge database of Ingenuity Pathway Analysis software used for downstream functional analyses. The most noticeable feature of this MCCA deficient skin fibroblast transcriptome was the typical genetic hallmark of mitochondrial dysfunction, decreased antioxidant response and disruption of energy homeostasis, which was confirmed by mitochondrial functional analyses. The MCC deficient transcriptome seems to predict oxidative stress that could alter the complex secondary cellular response that involve genes of the glycolysis, the TCA cycle, OXPHOS, gluconeogenesis, β-oxidation and the branched-chain fatty acid metabolism. An important emerging insight from this human MCCA transcriptome in combination with previous reports is that chronic exposure to the primary and secondary metabolites of MCC deficiency and the resulting oxidative stress might impact adversely on the quality of life and energy levels, irrespective of whether MCC deficient individuals are clinically affected or asymptomatic.

Antioxidant treatment ameliorates experimental diabetes-induced depressive-like behaviour and reduces oxidative stress in brain and pancreas

Studies have shown a relationship between diabetes mellitus (DM) and the development of major depressive disorder. Alterations in oxidative stress are associated with the pathophysiology of both diabetes mellitus and major depressive disorder. This study aimed to evaluate the effects of antioxidants N-acetylcysteine and deferoxamine on behaviour and oxidative stress parameters in diabetic rats. To this aim, after induction of diabetes by a single dose of alloxan, Wistar rats were treated with N-acetylcysteine or deferoxamine for 14 days, and then depressive-like behaviour was evaluated. Oxidative stress parameters were assessed in the prefrontal cortex, hippocampus, amygdala, nucleus accumbens and pancreas. Diabetic rats displayed depressive-like behaviour, and treatment with N-acetylcysteine reversed this alteration. Carbonyl protein levels were increased in the prefrontal cortex, hippocampus and pancreas of diabetic rats, and both N-acetylcysteine and deferoxamine reversed these alterations. Lipid damage was increased in the prefrontal cortex, hippocampus, amygdala and pancreas; however, treatment with N-acetylcysteine or deferoxamine reversed lipid damage only in the hippocampus and pancreas. Superoxide dismutase activity was decreased in the amygdala, nucleus accumbens and pancreas of diabetic rats. In diabetic rats, there was a decrease in catalase enzyme activity in the prefrontal cortex, amygdala, nucleus accumbens and pancreas, but an increase in the hippocampus. Treatment with antioxidants did not have an effect on the activity of antioxidant enzymes. In conclusion, animal model of diabetes produced depressive-like behaviour and oxidative stress in the brain and periphery. Treatment with antioxidants could be a viable alternative to treat behavioural and biochemical alterations induced by diabetes.

Impairment of calcium ATPases by high glucose and potential pharmacological protection

The review deals with impairment of Ca(2+)-ATPases by high glucose or its derivatives in vitro, as well as in human diabetes and experimental animal models. Acute increases in glucose level strongly correlate with oxidative stress. Dysfunction of Ca(2+)-ATPases in diabetic and in some cases even in nondiabetic conditions may result in nitration of and in irreversible modification of cysteine-674. Nonenyzmatic protein glycation might lead to alteration of Ca(2+)-ATPase structure and function contributing to Ca(2+) imbalance and thus may be involved in development of chronic complications of diabetes. The susceptibility to glycation is probably due to the relatively high percentage of lysine and arginine residues at the ATP binding and phosphorylation domains. Reversible glycation may develop into irreversible modifications (advanced glycation end products, AGEs). Sites of SERCA AGEs are depicted in this review. Finally, several mechanisms of prevention of Ca(2+)-pump glycation, and their advantages and disadvantages are discussed.

Neuroprotective effect of paeonol on cognition deficits of diabetic encephalopathy in streptozotocin-induced diabetic rat

Diabetic encephalopathy (DE) has been characterized by the impaired cognition and the abnormalities of neurochemistry and neurostructure. The study was conducted to evaluate the neuroprotective effect of paeonol on STZ-induced DE rats. Paeonol of 25, 50, 100mg/kg (p.o.) could decrease the latency time and path length, and enhance significantly the spent time in the target quadrant and platform crossings in Morris water maze test. The treatment with paeonol could also increase significantly Na(+)-K(+)-ATP enzyme and ChAT activities, as well as decreasing significantly AchE activity in hippocampal tissue. Immunohistochemistry and TUNEL staining showed that paeonol could attenuate apoptosis of neurons and caspase 3 expression, improve two neurotrophic factors BDNF and IGF expressions, and also ameliorate Aβ deposition in the hippocampus and cerebral cortex. In conclusion, the present study demonstrated diabetic rats treated with paeonol could ameliorate the cognition deficits. These findings indicated paeonol might act as a beneficial agent for the prevention and treatment of DE.

Oxidative Stress and Erythrocyte Membrane Alterations in Children with Autism: Correlation with Clinical Features

It has been suggested that oxidative stress may play a role in the pathogenesis of Autism Spectrum Disorders (ASD), but the literature reports somewhat contradictory results. To further investigate the issue, we evaluated a high number of peripheral oxidative stress parameters, and some related issues such as erythrocyte membrane functional features and lipid composition. Twenty-one autistic children (Au) aged 5 to 12 years, were gender and age-matched with 20 typically developing children (TD). Erythrocyte thiobarbituric acid reactive substances, urinary isoprostane and hexanoyl-lysine adduct levels were elevated in Au, thus confirming the occurrence of an imbalance of the redox status of Au, whilst other oxidative stress markers or associated parameters (urinary 8-oxo-dG, plasma radical absorbance capacity and carbonyl groups, erythrocyte superoxide dismutase and catalase activities) were unchanged. A very significant reduction of Na(+)/K(+)-ATPase activity (-66%, p<0.0001), a reduction of erythrocyte membrane fluidity and alteration in erythrocyte fatty acid membrane profile (increase in monounsaturated fatty acids, decrease in EPA and DHA-ω3 with a consequent increase in ω6/ω3 ratio) were found in Au compared to TD, without change in membrane sialic acid content. Some Au clinical features appear to be correlated with these findings; in particular, hyperactivity score appears to be related with some parameters of the lipidomic profile and membrane fluidity. Oxidative stress and erythrocyte membrane alterations may play a role in the pathogenesis of ASD and prompt the development of palliative therapeutic protocols. Moreover, the marked decrease in NKA could be potentially utilized as a peripheral biomarker of ASD.

Preventive effect of N-acetyl-L-cysteine on oxidative stress and cognitive impairment in hepatic encephalopathy following bile duct ligation

Oxidative stress caused by ammonia toxicity is known to play a key role in the pathogenesis of hepatic encephalopathy (HE). The present study was designed to evaluate the protective effect of N-acetyl-L-cysteine (NAC) supplementation in a bile duct ligation (BDL)-induced model of HE. Three weeks after BDL, rats developed biliary fibrosis which was supported by liver function tests, ammonia levels, and hydroxyproline content. Impaired cognitive and motor functions were observed along with decreased acetylcholinesterase activity in the brain of BDL rats. Cerebral cortex and cerebellum of BDL animals showed an increase in lipid peroxidation and reduction in total and nonprotein thiols along with reduction in antioxidant enzymes. Histopathological examination of cortex and cerebellum of BDL rats showed astrocytic swelling, inflammation, necrosis, and white matter edema. One week after BDL surgery, animals administered with NAC at a daily dose 100 mg/kg for 2 weeks showed significant improvement in the activity of liver marker enzymes and restored structural morphology of liver. NAC was able to ameliorate spatial memory and motor coordination deficits observed in BDL rats. NAC supplementation decreased lipid peroxidation and was also able to restore the activity of antioxidant enzymes as well as structural deficits observed in the cortex and cerebellum of BDL animals. The results clearly demonstrate that the protective effect of NAC in an experimental model of HE is mediated through attenuation of oxidative stress, suggesting a therapeutic role for NAC in individuals withHE.

Neurochemical evidence that the metabolites accumulating in 3-methylcrotonyl-CoA carboxylase deficiency induce oxidative damage in cerebral cortex of young rats

Isolated 3-methylcrotonyl-CoA carboxylase deficiency (3MCCD) is an autosomal recessive disorder of leucine metabolism biochemically characterized by accumulation of 3-methylcrotonylglycine (3MCG), 3-methylcrotonic acid (3MCA) and 3-hydroxyisovaleric acid. A considerable number of affected individuals present neurological symptoms with or without precedent crises of metabolic decompensation and brain abnormalities whose pathogenesis is poorly known. We investigated the in vitro effects of 3MCG and 3MCA on important parameters of oxidative stress in cerebral cortex of young rats. 3MCG and 3MCA significantly increased TBA-RS and carbonyl formation, indicating that these compounds provoke lipid and protein oxidation, respectively. In contrast, nitric oxide production was not affected by 3MCG and 3MCA. Furthermore, 3MCG- and 3MCA-induced elevation of TBA-RS values was fully prevented by melatonin, trolox and reduced glutathione, but not by the nitric oxide inhibitor N(ω)-nitro-L-arginine methyl ester or the combination of catalase plus superoxide dismutase, indicating that reactive oxygen species were involved in the oxidative damage caused by these compounds. We also found that the activity of the antioxidant enzymes glutathione peroxidase, catalase, superoxide dismutase and glutathione reductase were not altered in vitro by 3MCG and 3MCA. It is therefore presumed that alterations of the cellular redox homeostasis caused by the major metabolites accumulating in 3MCCD may potentially be involved in the pathophysiology of the neurological dysfunction and structural brain alterations found in patients affected by this disorder.

Tissue cholesterol content alterations in streptozotocin-induced diabetic rats

AIM

Diabetes is associated with elevated serum total cholesterol level and disrupted lipoprotein subfractions. The aim of this study was to examine alterations in the tissue cholesterol contents closely related to diabetic complications.

METHODS

Intraperitoneal injection of streptozotocin was used to induce type 1 diabetes in adult male Sprague-Dawley rats. On d 35 after the injection, liver, heart, intestine, kidney, pancreas, cerebral cortex and hippocampus were isolated from the rats. The content of total and free cholesterol in the tissues was determined using HPLC. The ATP-binding cassette protein A1 (ABCA1) protein and ApoE mRNA were measured using Western blot and QT-PCR analyses, respectively.

RESULTS

In diabetic rats, the level of free cholesterol was significantly decreased in the peripheral tissues, but significantly elevated in hippocampus, as compared with those in the control rats. Diabetic rats showed a trend of decreasing the total cholesterol level in the peripheral tissues, but significant change was only found in kidney and liver. In diabetic rats, the level of the ABCA1 protein was significantly increased in the peripheral tissues and cerebral cortex; the expression of ApoE mRNA was slightly decreased in hippocampus and cerebral cortex, but the change had no statistical significance.

CONCLUSION

Type 1 diabetes decreases the free cholesterol content in the peripheral tissues and increases the free cholesterol content in hippocampus. The decreased free cholesterol level in the peripheral tissues may be partly due to the increased expression of the ABCA1 protein.

Antidiabetic and neuroprotective effects of Trigonella foenum-graecum seed powder in diabetic rat brain

Trigonella foenum-graecum seed powder (TSP) has been reported to have hypoglycemic and hyperinsulinemic action. The objective of the study was to examine the antidiabetic and neuroprotective role of TSP in hyperglycemiainduced alterations in blood glucose, insulin levels and activities of membrane linked enzymes (Na+K+ATPase, Ca2+ATPase), antioxidant enzymes (superoxide dismutase, glutathione S-transferase), calcium (Ca2+) levels, lipid peroxidation, membrane fluidity and neurolipofuscin accumulation in the diabetic rat brain. Female Wistar rats weighing between 180 and 220 g were made diabetic by a single injection of alloxan monohydrate (15 mg/100 g body weight), diabetic rats were given 2 IU insulin, per day with 5% TSP in the diet for three weeks. A significant increase in lipid peroxidation was observed in diabetic brain. The increased lipid peroxidation following chronic hyperglycemia was accompanied with a significant increase in the neurolipofuscin deposition and Ca2+ levels with decreased activities of membrane linked ATPases and antioxidant enzymes in diabetic brain. A decrease in synaptosomal membrane fluidity may influence the activity of membrane linked enzymes in diabetes. The present study showed that TSP treatment can reverse the hyperglycemia induced changes to normal levels in diabetic rat brain. TSP administration amended effect of hyperglycemia on alterations in lipid peroxidation, restoring membrane fluidity, activities of membrane bound and antioxidant enzymes, thereby ameliorating the diabetic complications.

Beneficial effects of Trigonella foenum graecum and sodium orthovanadate on metabolic parameters in experimental diabetes

Oxidative stress in diabetic tissues is accompanied by high-level of free radicals with simultaneously declined antioxidant enzymes status leading to cell membrane damage. The present study was carried out to observe the effect of sodium orthovanadate (SOV) and Trigonella foenum graecum seed powder (TSP) administration on blood glucose and insulin levels, antioxidant enzymes, lipid peroxidation, pyruvate kinase, lactate dehydrogenase and protein kinase C in heart, muscle and brain of the alloxan-induced diabetic rats to see whether the treatment with SOV and TSP was capable of reversing the diabetic effects. Diabetes was induced by administration of alloxan monohydrate (15 mg/100 g body weight), and rats were treated with 2 IU insulin, 0.6 mg/ml SOV, 5% TSP in the diet and a combination of 0.2 mg/ml SOV and 5% TSP separately for 21 days. Blood glucose levels increased markedly in diabetic rats, animals treated with a combined dose of SOV and TSP had glucose levels almost comparable with controls, similar results were obtained in the activities of pyruvate kinase, lactate dehydrogenase, antioxidant enzymes and protein kinase C in diabetic animals. Our results showed that lower doses of SOV (0.2 mg/ml) could be used in combination with TSP to effectively reverse diabetic alterations in experimental diabetes.

Oxidative stress and cerebral endothelial cells: regulation of the blood-brain-barrier and antioxidant based interventions

While numerous lines of evidence point to increased levels of oxidative stress playing a causal role in a number of neurodegenerative conditions, our current understanding of the specific role of oxidative stress in the genesis and/or propagation of neurodegenerative diseases remains poorly defined. Even more challenging to the "oxidative stress theory of neurodegeneration" is the fact that many antioxidant-based clinical trials and therapeutic interventions have been largely disappointing in their therapeutic benefit. Together, these factors have led researchers to begin to focus on understanding the contribution of highly localized structures, and defined anatomical features, within the brain as the sites responsible for oxidative stress-induced neurodegeneration. This review focuses on the potential for oxidative stress within the cerebrovascular architecture serving as a modulator of neurodegeneration in a variety of pathological settings. In particular, this review highlights important implications for vascular-derived oxidative stress in the initiating and promoting pathophysiology in the brain, identifying new roles for cerebrovascular oxidative stress in a variety of brain disorders. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Neurochemical evidence that lysine inhibits synaptic Na+,K+-ATPase activity and provokes oxidative damage in striatum of young rats in vivo

Lysine (Lys) accumulation in tissues and biological fluids is the biochemical hallmark of patients affected by familial hyperlysinemia (FH) and other inherited metabolic disorders. In the present study we investigated the effects of acute administration of Lys on relevant parameters of energy metabolism and oxidative stress in striatum of young rats. We verified that Lys in vivo intrastriatal injection did not change the citric acid cycle function and creatine kinase activity, but, in contrast, significantly inhibited synaptic Na(+),K(+)-ATPase activity in striatum prepared 2 and 12 h after injection. Moreover, Lys induced lipid peroxidation and diminished the concentrations of glutathione 2 h after injection. These effects were prevented by the antioxidant scavengers melatonin and the combination of α-tocopherol and ascorbic acid. Lys also inhibited glutathione peroxidase activity 12 h after injection. Therefore it is assumed that inhibition of synaptic Na(+),K(+)-ATPase and oxidative damage caused by brain Lys accumulation may possibly contribute to the neurological manifestations of FH and other neurometabolic conditions with high concentrations of this amino acid.

Inhibition of aldehyde dehydrogenase 2 by oxidative stress is associated with cardiac dysfunction in diabetic rats

Left ventricular (LV) dysfunction is a common comorbidity in diabetic patients, although the molecular mechanisms underlying this cardiomyopathic feature are not completely understood. Aldehyde dehydrogenase 2 (ALDH2) has been considered a key cardioprotective enzyme susceptible to oxidative inactivation. We hypothesized that hyperglycemia-induced oxidative stress would influence ALDH2 activity, and ALDH2 inhibition would lead to cardiac functional alterations in diabetic rats. Diabetes was induced by intraperitoneal (i.p.) injection of 60 mg/kg streptozotocin. Rats were divided randomly into four groups: control, untreated diabetic, diabetic treated with N-acetylcysteine (NAC) and diabetic treated with α-lipoic acid (α-LA). Cardiac contractile function, oxidative stress markers and reactive oxygen species (ROS) levels were assessed. ALDH2 activity and expression also were determined. The role of ALDH2 activity in change in hyperglycemia-induced mitochondrial membrane potential (Δψ) was tested in cultured neonatal cardiomyocytes. Myocardial MDA content and ROS were significantly higher in diabetic rats than in controls, whereas GSH content and Mn-SOD activity were decreased in diabetic rats. Compared with controls, diabetic rats exhibited significant reduction in LV ejection fraction and fractional shortening, accompanied by decreases in ALDH2 activity and expression. NAC and α-LA attenuated these changes. Mitochondrial Δψ was decreased greatly with hyperglycemia treatment, and high glucose combined with ALDH2 inhibition with daidzin further decreased Δψ. The ALDH2 activity can be regulated by oxidative stress in the diabetic rat heart. ALDH2 inhibition may be associated with LV reduced contractility, and mitochondrial impairment aggravated by ALDH2 inhibition might reflect an underlying mechanism which causes cardiac dysfunction in diabetic rats.

Statin treatment reduces oxidative stress-associated apoptosis of sciatic nerve in diabetes mellitus

Statins are lipid-lowering drugs that are widely used for treating hyperlipidemia, especially in diabetic patients. The aim of our study was to explore the effects of atorvastatin on oxidative stress and apoptosis in the sciatic nerve due to hyperglycemia. Diabetes was induced by streptozotocin. Atorvastatin was given orally for two weeks beginning from the sixth week. Microscopic examination of sciatic nerve revealed that normal tissue organization was disrupted in streptozotocin induced diabetic rats. Treatment with Atorvastatin reduced the histological damage and protected the morphological integrity of the sciatic nerve in streptozotocin induced diabetes. Increased expressions of transforming growth factor beta-1, endothelial nitric oxide synthase and TUNEL in sciatic nerve from streptozotocin induced diabetes were reduced by Atorvastatin. Atorvastatin could improve the effects of oxidative stress and apoptosis on the sciatic nerve due to diabetes.

N-acetylcysteine inhibits hyperglycemia-induced oxidative stress and apoptosis markers in diabetic neuropathy

Several studies have indicated the involvement of oxidative stress in the development of diabetic neuropathy. In the present study, we have targeted oxidative stress mediated nerve damage in diabetic neuropathy using N-acetyl-l-cysteine (NAC), a potent antioxidant. After 8 weeks, streptozotocin-induced diabetic rats developed neuropathy which was evident from decreased tail-flick latency (thermal hyperalgesia). This was accompanied by decreased motor coordination as assessed by performance on rota-rod treadmill. Na(+) K(+) ATPase, a biochemical marker of development of diabetic neuropathy, was significantly inhibited in sciatic nerve of diabetic animals. NAC treatment at a daily dose between 1.4 and 1.5 g/kg body weight to diabetic animals for 7 weeks in drinking water ameliorated hyperalgesia, improved motor coordination and reversed reduction in Na(+) K(+) ATPase activity. There was an increase in lipid peroxidation in sciatic nerve of diabetic animals along with decrease in phospholipid levels, while NAC treatment attenuated lipid peroxidation and restored phospholipids to control levels. This was associated with decrease in glutathione and protein thiols. The activities of antioxidant enzymes; superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and glutathione-S-transferase were reduced in sciatic nerve of diabetic animals. Cytochrome c release and active caspase 3 were markedly increased in nerve from diabetic animals suggesting activation of apoptotic pathway. NAC treatment significantly ameliorated decrease in antioxidant defense and prevented cytochrome c release and caspase 3 activation. Electron microscopy revealed demyelination, Wallerian degeneration and onion-bulb formation in sciatic nerve of diabetic rats. NAC on the other hand was able to reverse structural deficits observed in sciatic nerve of diabetic rats. Our results clearly demonstrate protective effect of NAC is mediated through attenuation of oxidative stress and apoptosis, and suggest therapeutic potential of NAC in attenuation of diabetic neuropathy.

Glucose and corticosterone changes in developing and adult rats following exposure to (+/-)-3,4-methylendioxymethamphetamine or 5-methoxydiisopropyltryptamine

The use of the club drugs 3,4-methylenedioxymethamphetamine (MDMA) and 5-methoxy-n,n-diisopropyltryptamine (Foxy) is of growing concern, especially as many of the effects, particularly during development, are unknown. The effects of these drugs upon homeostasis may be important since both are known to stimulate the hypothalamic-pituitary-adrenal axis. The purpose of this experiment was to examine alterations in rats in corticosterone and glucose following an acute exposure to these drugs at different stages of development: preweaning, juvenile, and adulthood. Both MDMA and Foxy increased corticosterone levels significantly at all ages examined, while glucose was elevated at all stages except at the juvenile time point (postnatal day 28). For both measures, there were no differences between the sexes with either drug. The data indicate that an acute exposure to these drugs alters CORT and glucose levels, raising the possibility that these changes may have effects on behavioral and cognitive function, as we and others have previously demonstrated.