Increased Receptor for Advanced Glycation Endproducts Immunocontent in the Cerebral Cortex of Vitamin A-Treated Rats

Vitamin A, beyond its biological role, is an alternative choice in treating some life threatening pathologies, for instance leukemia and immunodeficiency. On the other hand, vitamin A therapy at moderate to high doses has caused concern among public health researchers due to the toxicological aspect resulting from such habit. It has been described hepatotoxicity, cognitive disturbances and increased mortality rates among subjects ingesting increased levels of vitamin A daily. Then, based on the previously reported data, we investigated here receptor for advanced glycation endproducts (RAGE) immunocontent and oxidative damage levels in cerebral cortex of vitamin A-treated rats at clinical doses (1,000–9,000 IU/kg day⁻¹). RAGE immunocontent, as well as oxidative damage levels, were observed increased in cerebral cortex of vitamin A-treated rats. Whether increased RAGE levels exert negative effects during vitamin A supplementation it remains to be investigated, but it is very likely that deleterious consequences may arise from such alteration.     

Vitamin A supplementation at pharmacological doses induces nitrosative stress on the hypothalamus of adult Wistar rats

Vitamin A is a micronutrient involved in the regulation of a normal mammalian brain function. In spite of this, it has been demonstrated that vitamin A exerts a wide range of deleterious effects regarding neuronal homeostasis, for instance impairing brain metabolism and suppressing neurogenesis, to cite a few. In addition, vitamin A is a redox active molecule, i.e. it is both anti- and pro-oxidant, depending on its concentration. In the herein presented work, we performed some experiments aiming to investigate the effects of clinically applied doses of vitamin A (1000–9000 IU/kg/day during 28 days) on rat hypothalamic redox state and mitochondrial electron transfer chain (METC) activity, as well as on hypothalamic α-synuclein and D2 receptor (dopamine receptor) contents. Additionally, we quantified caspase-3 activity and tumor necrosis factor-α (TNF-α) levels to assess either neuronal death or an inflammatory state in such brain area. We found that vitamin A supplementation increased free radical production, as well as oxidative and nitrosative stress, in rat hypothalamus. Also, we observed increased complex I-III activity, but decreased complex IV activity in the hypothalamus of vitamin A-treated rats, which may give rise to the increased superoxide anion (O₂⁻) production found here. Other parameters investigated here, i.e. α-synuclein and D2 receptor contents did not change. Even though we did not observe signs of increased cell death or inflammation in the rat hypothalamus, more attention is needed when vitamin A is the choice of treatment in certain pathologies.     

Rubella vaccine-induced cellular immunity: evidence of associations with polymorphisms in the Toll-like, vitamin A and D receptors, and innate immune response genes

Toll-like, vitamin A and D receptors and other innate proteins participate in various immune functions. We determined whether innate gene-sequence variations are associated with rubella vaccine-induced cytokine immune responses. We genotyped 714 healthy children (11–19 years of age) after two doses of rubella-containing vaccine for 148 candidate SNP markers. Rubella virus-induced cytokines were measured by ELISA. Twenty-two significant associations (range of P values 0.002–0.048) were found between SNPs in the vitamin A receptor family (RARA, RARB, TOP2B and RARG), vitamin D receptor and downstream mediator of vitamin D signaling (RXRA) genes and rubella virus-specific (IFN-γ, IL-2, IL-10, TNF-α, and GM-CSF) cytokine immune responses. A TLR3 gene promoter region SNP (rs5743305, −8441A > T) was associated with rubella-specific GM-CSF secretion. Importantly, SNPs in the TRIM5 gene coding regions, rs3740996 (His43Tyr) and rs10838525 (Gln136Arg), were associated with an allele dose-related secretion of rubella virus-specific TNF-α and IL-2/GM-CSF, respectively, and have been previously shown to have functional consequences regarding the antiviral activity and susceptibility to HIV-1 infection. We identified associations between individual SNPs and haplotypes in, or involving, the RIG-I (DDX58) gene and rubella-specific TNF-α secretion. This is the first paper to present evidence that polymorphisms in the TLR, vitamin A, vitamin D receptor, and innate immunity genes can influence adaptive cytokine responses to rubella vaccination.     

The Effect of Vitamin A Supplementation on Various Elements in Elite Taekwondo Players

The present study aims to examine the effects of both physical activity and vitamin A supplementation on trace element metabolism in individuals engaged in taekwondo. The study registered seven healthy male national taekwondo players whose mean age was 21.86 ± 0.34 years and mean weight was 64.86 ± 2.72 kg. The subjects were supplemented with oral administration of 100 mg vitamin A (retinol) for 6 weeks, and concurrently, they were subjected to taekwondo training 5 days a week. Before starting the vitamin A supplementation, blood samples were taken from the subjects twice, once at rest and once after exhaustion. Similarly, at the end of the 6-week vitamin A supplementation, two blood samples were taken from the subjects, once at rest and once after exhaustion, in order to determine (by atomic emission) and compare serum cobalt, molybdenum, calcium, cadmium, chromium, copper, manganese, sodium, nickel, phosphorus, sulfur, iron, boron, and zinc (mg/L) levels. Values of boron and nickel dropped significantly after 6-week vitamin A supplementation (p < 0.001). Reduced levels of boron and nickel we obtained in the present study are believed to result from the antioxidant effect of long-term vitamin A supplementation.     

Acamprosate Modulates Alcohol-Induced Hippocampal NMDA Receptors and Brain Microsomal Ca2+-ATPase but Induces Oxidative Stress in Rat

We investigated the effects of acamprosate on alcohol-induced oxidative toxicity, microsomal membrane Ca²⁺-ATPase (MMCA) activity and N-methyl-d-aspartate receptor (NMDAR) subunits in rat brain. Forty male rats were equally divided into four groups. The first group was used as control, and the second group received ethanol. Acamprosate and acamprosate plus ethanol each day were administered to rats constituting the third and fourth groups for 21 days, respectively. Brain cortical and hippocampal samples were taken from the four groups after 21 days. Brain cortical lipid peroxidation (LP) levels and MMCA activity were higher in the alcohol group than in control, although glutathione peroxidase (GSH-Px), vitamin C, vitamin E and β-carotene values were lower in the alcohol group than in control. LP levels were further increased in the acamprosate and alcohol + acamprosate groups compared with the alcohol group. GSH-Px, vitamin A, vitamin C, vitamin E and β-carotene in the acamprosate and alcohol + acamprosate groups were further decreased compared with the alcohol group. Hippocampal NMDAR 2A and 2B subunit concentrations were lower in the alcohol group than in control, although they were increased by acamprosate and alcohol + acamprosate. Brain cortical MMCA activity was higher in the acamprosate group than in the alcohol-treated rats, although its activity was lower in the alcohol + acamprosate group than in the acamprosate group. Brain cortical reduced glutathione levels were not found to be statistically different in any of the groups. Oxidative stress has been proposed to explain the biological side effects of experimental alcohol intake. Acamprosate and alcohol-induced oxidative stress decreased brain antioxidant vitamins in the alcoholic rats.     

Supplementation of curcumin and vitamin E enhances oxidative stress,but restores hepatic histoarchitecture in hypothyroid rats

AimsIn the present study, the effects of vitamin E and curcumin on hepatic dysfunction, mitochondrial oxygen consumption as well as hyperlipidemia in hypothyroid rats are reported.Main methodsAdult male rats were rendered hypothyroid by administration of 0.05% 6-n-propyl-2-thiouracil (PTU) in their drinking water, while vitamin E (200 mg/kg body weight) and curcumin (30 mg/kg body weight) were supplemented orally for 30 days.Key findingsHypothyroidism-induced elevation in serum aspartate aminotransferase activity was found to decline in vitamin E and curcumin treated rats. Nevertheless, distorted histoarchitecture revealed in hypothyroid rat liver was alleviated to normal by vitamin E and curcumin treatment. Regulation of hypothyroidism induced decrease in complexes I and II mediated mitochondrial respiration by vitamin E and curcumin was found to be different. Administration of curcumin to hypothyroid rats alleviates the decreased state 4 respiration and increased respiratory control ratio (RCR) level in complex I mediated mitochondrial oxygen consumption, whereas complex II mediated respiration was not influenced by exogenous antioxidants. Although, increase in serum concentration of total cholesterol was not modified by exogenous antioxidants, increased level of non-high-density lipoprotein cholesterol (non-HDL-C) in serum of hypothyroid rats was further enhanced by vitamin E and curcumin. Moreover, a significant elevation in mitochondrial lipid peroxidation and protein carbonylation was noticed in hypothyroid groups treated with vitamin E and curcumin.SignificanceThe present study suggests that supplementation of curcumin and vitamin E enhances oxidative stress parameters and hyperlipidemia; nevertheless, it protects hypothyroid-induced altered rectal temperature, serum transaminase activity and hepatic histoarchitecture.     

Vitamin D3 supplementation could ameliorate the inflammatory and redox status in the muscular phase of trichinellosis

Nutritional supplements, particularly vitamin D, have been widely used worldwide in the treatment of various infections, including parasites. This study aimed to evaluate the potential effects of vitamin D3 supplementation on the muscular phase of trichinellosis in experimental animals. Mice were divided as follows: (group I): infected untreated, (group IIa) infected and treated with vitamin D3 for 12 doses beginning 2 weeks before infection and continuing after infection, (group IIb) infected and treated with vitamin D3 for 8 doses beginning on the same day of infection, (group III) normal control, (group IVa) which received vitamin D3 for 12 doses and (group IVb) which received vitamin D3 for 8 doses. Mice were sacrificed 35 days after infection and total muscle larval count, and histopathological examination of muscle samples with immunohistochemical staining of cyclooxygenase 2 (COX2) and inducible nitric oxide synthase (iNOS) were performed. Muscle relative cathelicidin mRNA expression was assessed, as well as serum levels of muscle enzymes CK and LDH, interleukin-4 (IL-4), IL-10, IL-17 and interferon-gamma (INF-γ). Vitamin D3 supplementation significantly reduced muscle larval count, inflammatory cellular infiltration, COX2 and iNOS expression. Furthermore, it increased cathelicidin gene expression, decreased serum levels of CK and LDH and affected serum cytokine levels, increasing serum IL-4 and IL10 levels while decreasing serum INF γ and IL-17. In conclusion, vitamin D3 supplementation has favorable outcomes on the muscle phase of trichinellosis, including anti-inflammatory, antioxidant, and immunomodulatory effects.     

Endotoxemia impairs heart mitochondrial function by decreasing electron transfer, ATP synthesis and ATP content without affecting membrane potential

Acute endotoxemia (LPS, 10 mg/kg ip, Sprague Dawley rats, 45 days old, 180 g) decreased the O₂ consumption of rat heart (1 mm³ tissue cubes) by 33% (from 4.69 to 3.11 μmol O₂/min. g tissue). Mitochondrial O₂ consumption and complex I activity were also decreased by 27% and 29%, respectively. Impaired respiration was associated to decreased ATP synthesis (from 417 to 168 nmol/min. mg protein) and ATP content (from 5.40 to 4.18 nmol ATP/mg protein), without affecting mitochondrial membrane potential. This scenario is accompanied by an increased production of O₂^●− and H₂O₂ due to complex I inhibition. The increased NO production, as shown by 38% increased mtNOS biochemical activity and 31% increased mtNOS functional activity, is expected to fuel an increased ONOO⁻ generation that is considered relevant in terms of the biochemical mechanism. Heart mitochondrial bioenergetic dysfunction with decreased O₂ uptake, ATP production and contents may indicate that preservation of mitochondrial function will prevent heart failure in endotoxemia.     

Mitochondrial Calcium Transport and Mitochondrial Dysfunction After Global Brain Ischemia in Rat Hippocampus

Here we report effect of ischemia-reperfusion on mitochondrial Ca²⁺ uptake and activity of complexes I and IV in rat hippocampus. By performing 4-vessel occlusion model of global brain ischemia, we observed that 15 min ischemia led to significant decrease of mitochondrial capacity to accumulate Ca²⁺ to 80.8% of control whereas rate of Ca²⁺ uptake was not significantly changed. Reperfusion did not significantly change mitochondrial Ca²⁺ transport. Ischemia induced progressive inhibition of complex I, affecting final electron transfer to decylubiquinone. Minimal activity of complex I was observed 24 h after ischemia (63% of control). Inhibition of complex IV activity to 80.6% of control was observed 1 h after ischemia. To explain the discrepancy between impact of ischemia on rate of Ca²⁺ uptake and activities of both complexes, we performed titration experiments to study relationship between inhibition of particular complex and generation of mitochondrial transmembrane potential (ΔΨ_m). Generation of a threshold curves showed that complex I and IV activities must be decreased by approximately 40, and 60%, respectively, before significant decline in ΔΨ_m was documented. Thus, mitochondrial Ca²⁺ uptake was not significantly affected by ischemia-reperfusion, apparently due to excess capacity of the complexes I and IV. Inhibition of complex I is favourable of reactive oxygen species (ROS) generation. Maximal oxidative modification of membrane proteins was documented 1 h after ischemia. Although enhanced formation of ROS might contribute to neuronal injury, depressed activities of complex I and IV together with unaltered rate of Ca²⁺ uptake are conditions favourable of initiation of other cell degenerative pathways like opening of mitochondrial permeability transition pore or apoptosis initiation, and might represent important mechanism of ischemic damage to neurones.     

Role of Endoplasmic Reticulum Stress in the Amygdaloid Kindling Model of Rats

Endoplasmic reticulum (ER) is an organelle responsible for correct folding and sorting of proteins contributing to neurogenesis and neuronal cell death. We used rapid kindling to analyze specific ER stress marker expression underlying focal epileptogenesis. Seven-week-old rats were divided into three groups: sham (n = 6), partially kindled (n = 8), and over-kindled rats (n = 9). Over kindled rats received over100 stimuli. Partially kindled animals had stimuli halted at stage 2. Protein from ipsilateral hippocampus was electrophoresed on SDS–PAGE, followed by hybridization with primary antibodies, anti-KDEL (-Lys-Asp-Glu-coo-), Bcl-2, BDNF (brain-derived neurotrophic factor), CHOP (C/EBP-homolog protein), C/EBP (CCAAT/enhancer-binding protein), NMDA (N-methyl-d-aspartate; -R1 &2A), GluR1 (glutamate receptor), and β-tubulin. Western blotting revealed that the ER stress marker BiP (immunoglobulin heavy chain-binding protein) was markedly increased in both partially- and over-kindled groups. BiP expression was ninefold greater than control in partially kindling while twofold greater than control in over-kindled animals. Although ER stress response was accelerated, CHOP expression, which upregulates when apoptosis signaling is accelerated by ER stress, was suppressed. Bcl-2, which acts as an anti-apoptotic molecule, was upregulated in the over-kindled group. Remarkable elevation of BiP was found in partially kindled animals, but not in over-kindled. Over-kindled rats had spontaneous generalized seizure, while partially kindled ones had only partial seizures. Elevation of markers of ER stress in partial seizures might reflect transfer of discharge to contralateral limbic structures. We observed indications of functional changes and neurogenesis in limbic structure during kindling. Widespread indications of functional changes in several membrane and secreted proteins, including NMDA-R1 & R2A and BDNF, for mossy fiber re-construction on the CA3 area, which are related to protein synthesis in the ER, may be important in epileptogenesis.     

Chronic Unpredictable Stress Before Pregnancy Reduce the Expression of Brain-Derived Neurotrophic Factor and N-Methyl-D-Aspartate Receptor in Hippocampus of Offspring Rats Associated with Impairment of Memory

To investigate the effect of stress before pregnancy on memory function and serum corticosterone (COR) levels, as well as the expression of brain-derived neurotrophic factor (BDNF), N-methyl-D-aspartate (NMDA) 2A (NR2A) and 2B (NR2B) receptors in the hippocampus of the offspring rats when they were 2 months postnatally. Adult female Sprague-Dawley (SD) rats were divided randomly into two groups: control group (n = 8) and chronic unpredictable stress (CUS) group (n = 12). All rats were tested in the open field test and sucrose intake test before and after CUS. The memory function of their offspring were tested in the Morris water maze. Serum COR levels were determined by using a standard radioimmunoassay kit. The expression of BDNF, NR2A and NR2B in the hippocampus of the offspring rats were studied by immunoreactivity quantitative analysis and real-time RT-PCR. (1) Following CUS, reduced open field test activity and decreased sucrose consumption were observed relative to controls. (2) The Morris water maze task demonstrated increased escape latency in the offspring rats of CUS group relative to controls (P < 0.01). No-platform probe testing showed reduced crossings for offspring of CUS relative to controls (P < 0.05). (3) CUS induced a significant increase in serum COR levels of the offspring rats (P < 0.01), but no difference was observed in the body or brain weight between the offspring of the two groups. (4) Immunoreactivity quantitative analysis shows that BDNF and NR2B in the offspring of CUS group was decreased in the CA3 and DG regions of the hippocampus compared to the control group offspring, but NR2A levels were not altered between the offspring of the two groups. (5) Real-time RT-PCR demonstrated that BDNF and NR2B mRNAs were significantly decreased in the offspring of the CUS group compared with the control group (P < 0.01). No significant difference in the levels of NR2A mRNA was detected between offspring of CUS and offspring of control groups. In our study, pregestational stress can increase serum corticosterone levels and reduce the expression of BDNF and NR2B in the hippocampus of offspring. These alterations are associated with impairment of memory in the adult offspring. These data suggest that, stress before pregnancy might have a profound influence on brain development of offspring, that may persist into and be manifested in adulthood.     

Exercise performance, red blood cell deformability, and lipid peroxidation: effects of fish oil and vitamin E

Oostenbrug, G. S., R. P. Mensink, M. R. Hardeman, T. DeVries, F. Brouns, and G. Hornstra. Exercise performance, red bloodcell deformability, and lipid peroxidation: effects of fish oil andvitamin E. J. Appl. Physiol. 83(3):746-752, 1997.Previous studies have indicated that fish oilsupplementation increases red blood cell (RBC) deformability, which mayimprove exercise performance. Exercise alone, or in combination with anincrease in fatty acid unsaturation, however, may enhance lipidperoxidation. Effects of a bicycle time trial of ~1 h on RBCcharacteristics and lipid peroxidation were, therefore, studied in 24 trained cyclists. After 3 wk of fish oil supplementation (6 g/day),without or with vitamin E (300 IU/day), trial performance,RBC characteristics, and lipid peroxidation were measuredagain. RBC deformability appeared to decrease duringendurance exercise. After correction for hemoconcentration, plasmatotal tocopherol concentrations decreased by 0.77 µmol/l(P = 0.012) or 2.9% and carotenoidconcentrations by 0.08 µmol/l (P = 0.0008) or 4.5%. Endurance exercise did not affect the lag time andrate of in vitro oxidation of low-density lipoproteins (LDLs), but themaximum amount of conjugated dienes formed decreased by 2.1 ± 1.0 µmol/mmol LDL cholesterol (P = 0.042) or 1.2%. Fish oil supplementation with andwithout vitamin E did not affect RBC characteristics or exerciseperformance. Both supplements decreased the rate of LDL oxidation, andfish oil supplementation with vitamin E delayed oxidation. The amountof dienes, however, was not affected. The supplements also did notchange effects of exercise. We conclude that the changes observedduring endurance exercise may indicate increased oxidative stress, butfurther research is necessary to confirm this. Fish oil supplementation does not improve endurance performance, but it also does not cause oraugment changes in antioxidant levels or LDL oxidation during exercise.

     

Effect of Dietary Vitamin A on Reproductive Performance and Immune Response of Broiler Breeders

The effects of dietary vitamin A supplementation on reproductive performance, liver function, fat-soluble vitamin retention, and immune response were studied in laying broiler breeders. In the first phase of the experiment, 1,120 Ross-308 broiler breeder hens were fed a diet of corn and soybean meal supplemented with 5,000 to 35,000 IU/kg vitamin A (retinyl acetate) for 20 weeks. In the second phase, 384 Ross-308 broiler breeder hens were fed the same diet supplemented with 5,000 to 135,000 IU/kg vitamin A (retinyl acetate) for 24 weeks. The hens'' reproductive performance, the concentrations of vitamins A and E in liver and egg yolk, liver function, mRNA expression of vitamin D receptor in duodenal mucosa, antibody titers against Newcastle disease virus vaccine, and T-cell proliferation responses were evaluated. Supplementation of vitamin A at levels up to and including 35,000 IU/kg did not affect reproductive performance and quadratically affected antibody titer to Newcastle disease virus vaccine (p<0.05). Dietary addition of vitamin A linearly increased vitamin A concentration in liver and yolk and linearly decreased α-, γ-, and total tocopherol concentration in yolk (p<0.01) and α-tocopherol in liver (p<0.05). Supplementation of vitamin A at doses of 45,000 IU/kg and above significantly decreased egg weight, yolk color, eggshell thickness and strength, and reproductive performance. Dietary vitamin A significantly increased mRNA expression of vitamin D receptor in duodenal mucosa (p<0.05), increased aspartate amino transferase activity, and decreased total bilirubin concentration in serum. Supplementation of vitamin A at 135,000 IU/kg decreased the proliferation of peripheral blood lymphocytes (p<0.05). Therefore, the maximum tolerable dose of vitamin A for broiler breeders appears to be 35,000 IU/kg, as excessive supplementation has been shown to impair liver function, reproductive performance, and immune response.     

Glutamate induces H2O2 synthesis in nonsynaptic brain mitochondria

Mitochondrial reactive oxygen species regulate many important biological processes. We studied H₂O₂ formation by nonsynaptic brain mitochondria in response to the addition of low concentrations of glutamate, an excitatory neurotransmitter. We demonstrated that glutamate at concentrations from 10 to 50 μM stimulated the H₂O₂ generation in mitochondria up to 4-fold, in a dose-dependent manner. The effect of glutamate was observed only in the presence of Ca²⁺ (20 μM) in the incubation medium, and the rate of calcium uptake by the brain mitochondria was increased by up to 50% by glutamate. Glutamate-dependent effects were sensitive to the NMDA receptor inhibitors MK-801 (10 μM) and D-AP5 (20 μM) and the inhibitory neurotransmitter glycine (5 mM). We have shown that the H₂O₂ formation caused by glutamate is associated with complex II and is dependent on the mitochondrial potential. We have found that nonsynaptic brain mitochondria are a target of direct glutamate signaling, which can specifically activate H₂O₂ formation through mitochondrial respiratory chain complex II. The H₂O₂ formation induced by glutamate can be blocked by glycine, an inhibitory neurotransmitter that prevents the deleterious effects of glutamate in brain mitochondria.     

Tetramethylpyrazine Attenuates Cognitive Impairment Via Suppressing Oxidative Stress,Neuroinflammation, and Apoptosis in Type 2 Diabetic Rats

Cognitive dysfunction is an important complication observed in type 2 diabetes mellitus (T2DM) patients. Tetramethylpyrazine (TMP) is known to exhibit anti-diabetic and neuroprotective properties. Therefore, the present study aimed to investigate the possible therapeutic effects of TMP against type 2 diabetes-associated cognitive impairment in rats. High-fat diet (HFD) followed by a low dose of streptozotocin (35 mg/kg) was used to induce diabetes in Sprague–Dawley rats. TMP (20, 40, and 80 mg/kg) and Pioglitazone (10 mg/kg) were administered for 4 weeks. The Morris water maze (MWM) and novel objective recognition task (NOR) tests were used to assess memory function. Fasting blood glucose (FBG), lipid profile, HOMA-IR, glycosylated hemoglobin (HbA1c), and glucose tolerance were measured. Acetylcholinesterase (AChE) and choline acetytransferase (ChAT) activity, acetylcholine (ACh) levels, oxidative stress, apoptotic (Bcl-2, Bax, caspase-3), and inflammatory markers (TNF-α, IL-1β, and NF-kβ) were assessed. BDNF, p-AKT, and p-CREB levels were also measured. In the present work, we observed that treatment of diabetic rats with TMP alleviated learning and memory deficits, improved insulin sensitivity, and attenuated hyperglycemia and dyslipidemia. Furthermore, treatment with TMP increased BDNF, p-Akt, and p-CREB levels, normalized cholinergic dysfunction, and suppressed oxidative, inflammatory, and apoptotic markers in the hippocampus. Collectively, our results suggest that the TMP may be an effective neuroprotective agent in alleviating type 2 diabetes-associated cognitive deficits.

     

Redox regulation of mitochondrial fission,protein misfolding,synaptic damage,and neuronal cell death: potential implications for Alzheimer’s and Parkinson’s diseases

Normal mitochondrial dynamics consist of fission and fusion events giving rise to new mitochondria, a process termed mitochondrial biogenesis. However, several neurodegenerative disorders manifest aberrant mitochondrial dynamics, resulting in morphological abnormalities often associated with deficits in mitochondrial mobility and cell bioenergetics. Rarely, dysfunctional mitochondrial occur in a familial pattern due to genetic mutations, but much more commonly patients manifest sporadic forms of mitochondrial disability presumably related to a complex set of interactions of multiple genes (or their products) with environmental factors (G × E). Recent studies have shown that generation of excessive nitric oxide (NO), in part due to generation of oligomers of amyloid-β (Aβ) protein or overactivity of the NMDA-subtype of glutamate receptor, can augment mitochondrial fission, leading to frank fragmentation of the mitochondria. S-Nitrosylation, a covalent redox reaction of NO with specific protein thiol groups, represents one mechanism contributing to NO-induced mitochondrial fragmentation, bioenergetic failure, synaptic damage, and eventually neuronal apoptosis. Here, we summarize our evidence in Alzheimer’s disease (AD) patients and animal models showing that NO contributes to mitochondrial fragmentation via S-nitrosylation of dynamin-related protein 1 (Drp1), a protein involved in mitochondrial fission. These findings may provide a new target for drug development in AD. Additionally, we review emerging evidence that redox reactions triggered by excessive levels of NO can contribute to protein misfolding, the hallmark of a number of neurodegenerative disorders, including AD and Parkinson’s disease. For example, S-nitrosylation of parkin disrupts its E3 ubiquitin ligase activity, and thereby affects Lewy body formation and neuronal cell death.