Neonatal hyperglycemia induces oxidative stress in the rat brain: the role of pentose phosphate pathway enzymes and NADPH oxidase

Transcutaneous auricular vagus nerve stimulation may benefit from the addition of N-acetylcysteine to facilitate motor learning in infants of diabetic mothers failing oral feeds

Objective

This study aims to determine if pretreating with enteral N-acetylcysteine (NAC) improves CNS oxidative stress and facilitates improvement in oromotor skills during transcutaneous auricular nerve stimulation (taVNS) paired with oral feedings in infants of diabetic mothers (IDMs) who are failing oral feeds.

Methods

We treated 10 IDMs who were gastrostomy tube candidates in an open-label trial of NAC and taVNS paired with oral feeding. NAC (75 or 100 mg/kg/dose) was given by nasogastric (NG) administration every 6 h for 4 days, then combined with taVNS paired with 2 daily feeds for another 14 days. NAC pharmacokinetic (PK) parameters were determined from plasma concentrations at baseline and at steady state on day 4 of treatment in conjunction with magnetic resonance spectroscopic (MRS) quantification of CNS glutathione (GSH) as a marker of oxidative stress. We compared increases in oral feeding volumes before and during taVNS treatment and with a prior cohort of 12 IDMs who largely failed to achieve full oral feeds with taVNS alone.

Results

NAC 100 mg/kg/dose every 6 h NG resulted in plasma [NAC] that increased [GSH] in the basal ganglia with a mean of 0.13 ± 0.08 mM (p = 0.01, compared to baseline). Mean daily feeding volumes increased over 14 days of NAC + taVNS compared to the 14 days before treatment and compared to the prior cohort of 12 IDMs treated with taVNS alone. Seven IDMs reached full oral feeds sufficient for discharge, while three continued to have inadequate intake.

Conclusion

In IDM failing oral feeds, NAC 100 mg/kg/dose every 6 h NG for 4 days before and during taVNS paired with oral feeding increased CNS GSH, potentially mitigating oxidative stress, and was associated with improving functional feeding outcomes compared to taVNS alone in a prior cohort. This represents a novel approach to neuromodulation and supports the concept that mitigation of ongoing oxidative stress may increase response to taVNS paired with a motor task.

Stress hyperglycemia exacerbates inflammatory brain injury after stroke

Post-stroke hyperglycemia occurs in 30% - 60% of ischemic stroke patients as part of the systemic stress response, but neither clinical evidence nor pre-clinical studies indicate whether post-stroke hyperglycemia affects stroke outcome. Here we investigated this issue using a mouse model of permanent ischemia. Mice were maintained either normoglycemic or hyperglycemic during the interval of 17 - 48 hours after ischemia onset. Post-stroke hyperglycemia was found to increase infarct volume, blood-brain barrier disruption, and hemorrhage formation, and to impair motor recovery. Post-stroke hyperglycemia also increased superoxide formation by peri-infarct microglia/macrophages. In contrast, post-stroke hyperglycemia did not increase superoxide formation or exacerbate motor impairment in p47 phox-/- mice, which cannot form an active superoxide-producing NADPH oxidase-2 complex. These results suggest that hyperglycemia occurring hours-to-days after ischemia can increase oxidative stress in peri-infarct tissues by fueling NADPH oxidase activity in reactive microglia/macrophages, and by this mechanism contribute to worsened functional outcome.

Higher Dose Noninvasive Transcutaneous Auricular Vagus Nerve Stimulation Increases Feeding Volumes and White Matter Microstructural Complexity in Open-Label Study of Infants Slated for Gastrostomy Tube

OBJECTIVE

To determine whether transcutaneous auricular vagus nerve stimulation (taVNS) paired with twice daily bottle feeding increases the volume of oral feeds and white matter neuroplasticity in term-age-equivalent infants failing oral feeds and determined to need a gastrostomy tube.

STUDY DESIGN

In this prospective, open-label study, 21 infants received taVNS paired with 2 bottle feeds for 2 - 3 weeks (2x). We compared 1) increase oral feeding volumes with 2x taVNS and previously reported once daily taVNS (1x) to determine a dose response, 2) number of infants who attained full oral feeding volumes, and 3) diffusional kurtosis imaging and magnetic resonance spectroscopy before and after treatment by paired t tests.

RESULTS

All 2x taVNS treated infants significantly increased their feeding volumes compared with 10 days before treatment. Over 50% of 2x taVNS infants achieved full oral feeds but in a shorter time than 1x cohort (median 7 days [2x], 12.5 days [1x], P < .05). Infants attaining full oral feeds showed greater increase in radial kurtosis in the right corticospinal tract at the cerebellar peduncle and external capsule. Notably, 75% of infants of diabetic mothers failed full oral feeds, and their glutathione concentrations in the basal ganglia, a measure of central nervous system oxidative stress, were significantly associated with feeding outcome.

CONCLUSIONS

In infants with feeding difficulty, increasing the number of daily taVNS-paired feeding sessions to twice-daily significantly accelerates response time but not the overall response rate of treatment. taVNS was associated with white matter motor tract plasticity in infants able to attain full oral feeds.

TRIAL REGISTRATION

Clinicaltrials.gov (NCT04643808).

Cognitive dysfunction in diabetes: abnormal glucose metabolic regulation in the brain

Cognitive dysfunction is increasingly recognized as a complication and comorbidity of diabetes, supported by evidence of abnormal brain structure and function. Although few mechanistic metabolic studies have shown clear pathophysiological links between diabetes and cognitive dysfunction, there are several plausible ways in which this connection may occur. Since, brain functions require a constant supply of glucose as an energy source, the brain may be more susceptible to abnormalities in glucose metabolism. Glucose metabolic abnormalities under diabetic conditions may play an important role in cognitive dysfunction by affecting glucose transport and reducing glucose metabolism. These changes, along with oxidative stress, inflammation, mitochondrial dysfunction, and other factors, can affect synaptic transmission, neural plasticity, and ultimately lead to impaired neuronal and cognitive function. Insulin signal triggers intracellular signal transduction that regulates glucose transport and metabolism. Insulin resistance, one hallmark of diabetes, has also been linked with impaired cerebral glucose metabolism in the brain. In this review, we conclude that glucose metabolic abnormalities play a critical role in the pathophysiological alterations underlying diabetic cognitive dysfunction (DCD), which is associated with multiple pathogenic factors such as oxidative stress, mitochondrial dysfunction, inflammation, and others. Brain insulin resistance is highly emphasized and characterized as an important pathogenic mechanism in the DCD.

Brain-Oriented Strategies for Neuroprotection of Asphyxiated Newborns in the First Hours of Life

Perinatal asphyxia represents the first cause of severe neurological disabilities and the second cause of neonatal death in term-born babies. Currently, no treatment can prevent immediate cell death from necrosis, but some therapeutic interventions, such as therapeutic hypothermia (TH), can reduce delayed cell death from apoptosis. TH significantly improves the combined outcome of mortality or major neurodevelopmental disability, but the number of patients to be treated is 7 to get 1 child with no adverse neurological outcome. The aim of this educational review is to analyze the other care strategies to be implemented to improve the neurological outcome of children with hypoxic ischemic encephalopathy (HIE). Hypocapnia, hypoglycemia, pain control, and functional brain monitoring are recognized as appropriate approaches to improve outcome in critically ill infants with HIE. Pharmacologic neuroprotective adjuncts are currently under investigation. New drugs such as allopurinol and melatonin seem to provide positive effects although more randomized controlled trials are required to establish the effective therapeutic scheme. In the meantime, sustaining the respiratory, metabolic, and cardiovascular system during TH can be a valuable aid in managing and treating the patient with HIE in an optimal way.

Cerebral Effects of Neonatal Dysglycemia

This article summarizes the available evidence reporting the relationship between perinatal dysglycemia and long-term neurodevelopment. We review the physiology of perinatal glucose metabolism and discuss the controversies surrounding definitions of perinatal dysglycemia. We briefly review the epidemiology of hypoglycemia and hyperglycemia in fetal, preterm, and term infants. We discuss potential pathophysiologic mechanisms contributing to dysglycemia and its effect on neurodevelopment. We highlight current strategies to prevent and treat dysglycemia in the context of neurodevelopmental outcomes. Finally, we discuss areas of future research and the potential role of continuous glucose monitoring.

Nutrition and management of glycemia in neonates with neonatal encephalopathy treated with hypothermia

Adequate nutrition and glycemic homeostasis are increasingly recognized as potentially neuroprotective for the developing brain. In the context of hypoxia-ischemia, evidence is scarce regarding optimal nutritional support and administration route, as well as the short- and long-term consequences of such interventions. In this review, we summarize current knowledge on disturbances of brain metabolism of glucose and substrates by hypoxia-ischemia, and compound effects of these mechanisms on brain injury characterized by specific patterns on EEG and MRI. Risks and benefits of nutrition delivery via parenteral or enteral routes are examined. Nutrition could mitigate adverse neurodevelopmental outcomes, and the impact of nutritional strategies and specific nutritional interventions are reviewed. Limited literature highlights the need for further studies to understand the changes in energy metabolism during and after hypoxic-ischemic injury, to optimize nutritional regimens and glucose management, and to inform the neuroprotective role of nutrition.

Pioglitazone Ameliorates Lipopolysaccharide-Induced Behavioral Impairment, Brain Inflammation, White Matter Injury and Mitochondrial Dysfunction in Neonatal Rats

Previous studies have demonstrated that pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, inhibits ischemia-induced brain injury. The present study was conducted to examine whether pioglitazone can reduce impairment of behavioral deficits mediated by inflammatory-induced brain white matter injury in neonatal rats. Intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 2 mg/kg) was administered to Sprague-Dawley rat pups on postnatal day 5 (P5), and i.p. administration of pioglitazone (20 mg/kg) or vehicle was performed 5 min after LPS injection. Sensorimotor behavioral tests were performed 24 h after LPS exposure, and changes in biochemistry of the brain was examined after these tests. The results show that systemic LPS exposure resulted in impaired sensorimotor behavioral performance, reduction of oligodendrocytes and mitochondrial activity, and increases in lipid peroxidation and brain inflammation, as indicated by the increment of interleukin-1β (IL-1β) levels and number of activated microglia in the neonatal rat brain. Pioglitazone treatment significantly improved LPS-induced neurobehavioral and physiological disturbances including the loss of body weight, hypothermia, righting reflex, wire-hanging maneuver, negative geotaxis, and hind-limb suspension in neonatal rats. The neuroprotective effect of pioglitazone against the loss of oligodendrocytes and mitochondrial activity was associated with attenuation of LPS-induced increment of thiobarbituric acid reactive substances (TBARS) content, IL-1β levels and number of activated microglia in neonatal rats. Our results show that pioglitazone prevents neurobehavioral disturbances induced by systemic LPS exposure in neonatal rats, and its neuroprotective effects are associated with its impact on microglial activation, IL-1β induction, lipid peroxidation, oligodendrocyte production and mitochondrial activity.

Preliminary results of PBA-loaded nanoparticles development and the effect on oxidative stress and neuroinflammation in rats submitted to a chemically induced chronic model of MSUD

Maple syrup urine disease (MSUD) is a genetic disorder that leads the accumulation of branched-chain amino acids (BCAA) leucine (Leu), isoleucine, valine and metabolites. The symptomatology includes psychomotor delay and mental retardation. MSUD therapy comprises a lifelong protein strict diet with low BCAA levels and is well established that high concentrations of Leu and/or its ketoacid are associated with neurological symptoms. Recently, it was demonstrated that the phenylbutyrate (PBA) have the ability to decrease BCAA concentrations. This work aimed the development of lipid-based nanoparticles loaded with PBA, capable of targeting to the central nervous system in order to verify its action mechanisms on oxidative stress and cell death in brain of rats subjected to a MSUD chronic model. PBA-loaded nanoparticles treatment was effective in significantly decreasing BCAA concentration in plasma and Leu in the cerebral cortex of MSUD animals. Furthermore, PBA modulate the activity of catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase enzymes, as well as preventing the oxidative damage to lipid membranes and proteins. PBA was also able to decrease the glial fibrillary acidic protein concentrations and partially decreased the reactive species production and caspase-3 activity in MSUD rats. Taken together, the data indicate that the PBA-loaded nanoparticles could be an efficient adjuvant in the MSUD therapy, protecting against oxidative brain damage and neuroinflammation.

DHEA-pretreatment attenuates oxidative stress in kidney-cortex and liver of diabetic rabbits and delays development of the disease

In view of reported discrepancies concerning antioxidant activity of dehydroepiandrosterone (DHEA), a widely used dietary supplement, the current investigation was undertaken to evaluate the antioxidant properties of DHEA in both kidney-cortex and liver of alloxan (ALX)-induced diabetic rabbits, as this diabetogenic compound exhibits the ROS-dependent action. ALX was injected to animals following 7 days of DHEA administration. Four groups of rabbits were used in the experiments: control, DHEA-treated control, diabetic and DHEA-treated diabetic. Our results show for the first time, that in kidney-cortex DHEA resulted in normalization of hydroxyl free radicals (HFR) levels and restoration of catalase (CAT) and glutathione peroxidase (GPx) activities to near the control values, while in liver DHEA prevented the malondialdehyde (MDA) accumulation and normalized glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH) activities. Moreover, in both kidney-cortex and liver DHEA supplementation prevented GSSG elevation accompanied by a decrease in GSH/GSSG ratio. Although DHEA attenuated oxidative stress in both kidney-cortex and liver of ALX-induced diabetic rabbits and significantly delayed the onset of diabetes in time, it did not protect against the final development of diabetes. In conclusion, the current investigation underscores the complexity of the antioxidant action of DHEA. The data are of clinical interest since DHEA supplementation could prevent the deleterious effects of ROS and delay, or even prevent the onset of many diseases. However, in view of the reported pro-oxidant effects of high DHEA doses, the potential use of this agent as a supplement needs a careful evaluation.

Interleukin-1 receptor antagonist ameliorates the pain hypersensitivity, spinal inflammation and oxidative stress induced by systemic lipopolysaccharide in neonatal rats

Perinatal inflammation-induced reduction in pain threshold may alter pain sensitivity to hyperalgesia or allodynia which may persist into adulthood. In this study, we investigated the anti-inflammatory protective effect of interleukin-1 receptor antagonist (IL-1ra), an anti-inflammatory cytokine, on systemic lipopolysaccharide (LPS)-induced spinal cord inflammation and oxidative stress, thermal hyperalgesia, and mechanical allodynia in neonatal rats. Intraperitoneal (i.p.) injection of LPS (2 mg/kg) or sterile saline was performed in postnatal day 5 (P5) rat pups, and IL-1ra (100 mg/kg) or saline was administered (i.p.) 5 min after LPS injection. Pain reflex behavior, spinal cord inflammation and oxidative stress were examined 24 h after LPS administration. Systemic LPS exposure led to a reduction of tactile threshold in the von Frey filament tests (mechanical allodynia) and pain response latency in the tail-flick test (thermal hyperalgesia) of P6 neonatal rats. Spinal cord inflammation was indicated by the increased numbers of activated glial cells including microglia (Iba1+) and astrocytes (GFAP+), and elevated levels of pro-inflammatory cytokine interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2), and prostaglandin E2 (PGE2) 24 h after LPS treatment. LPS treatment induced spinal oxidative stress as evidenced by the increase in thiobarbituric acid reactive substances (TBARS) content in the spinal cord. LPS exposure also led to a significant increase in oligodendrocyte lineage population (Olig2+) and mature oligodendrocyte cells (APC+) in the neonatal rat spinal cord. IL-1ra treatment significantly reduced LPS-induced effects including hyperalgesia, allodynia, the increased number of activated microglia, astrocytes and oligodendrocytes, and elevated levels of IL-1β, COX-2, PGE2, and lipid peroxidation (TBARS) in the neonatal rat spinal cord. These data suggest that IL-1ra provides a protective effect against the development of pain hypersensitivity, spinal cord inflammation and oxidative stress in the neonatal rats following LPS exposure, which may be associated with the blockade of LPS-induced pro-inflammatory cytokine IL-1β.

D-ribose is elevated in T1DM patients and can be involved in the onset of encephalopathy

Although many mechanisms have been proposed for diabetic encephalopathy in type 2 diabetes mellitus (T2DM), the risk factors for cognitive impairment in type 1 diabetes mellitus (T1DM) are less clear. Here, we show that streptozotocin (STZ)-induced T1DM rats showed cognitive impairment in both Y maze and Morris water maze assays, accompanied with D-ribose was significantly increased in blood and urine, in addition to D-glucose. Furthermore, advanced glycation end products (AGE), Tau hyperphosphorylation and neuronal death in the hippocampal CA4/DG region were detected in T1DM rats. The expression and activity of transketolase (TKT), an important enzyme in the pentose shunt, were decreased in the brain, indicating that TKT may be involved in D-ribose metabolism in T1DM. Support for these change was demonstrated by the activation of TKT with benfotiamine (BTMP) treatment. Decreased D-ribose levels but not D-glucose levels; markedly reduced AGE accumulation, Tau hyperphosphorylation, and neuronal death; and improved cognitive ability in T1DM rats were shown after BTMP administration. In clinical investigation, T1DM patients had high D-ribose levels in both urine and serum. Our work suggests that D-ribose is involved in the cognitive impairment in T1DM and may provide a potentially novel target for treating diabetic encephalopathy.

Glycolysis-Derived Compounds From Astrocytes That Modulate Synaptic Communication

Based on the concept of the tripartite synapse, we have reviewed the role of glucose-derived compounds in glycolytic pathways in astroglial cells. Glucose provides energy and substrate replenishment for brain activity, such as glutamate and lipid synthesis. In addition, glucose metabolism in the astroglial cytoplasm results in products such as lactate, methylglyoxal, and glutathione, which modulate receptors and channels in neurons. Glucose has four potential destinations in neural cells, and it is possible to propose a crossroads in “X” that can be used to describe these four destinations. Glucose-6P can be used either for glycogen synthesis or the pentose phosphate pathway on the left and right arms of the X, respectively. Fructose-6P continues through the glycolysis pathway until pyruvate is formed but can also act as the initial compound in the hexosamine pathway, representing the left and right legs of the X, respectively. We describe each glucose destination and its regulation, indicating the products of these pathways and how they can affect synaptic communication. Extracellular L-lactate, either generated from glucose or from glycogen, binds to HCAR1, a specific receptor that is abundantly localized in perivascular and post-synaptic membranes and regulates synaptic plasticity. Methylglyoxal, a product of a deviation of glycolysis, and its derivative D-lactate are also released by astrocytes and bind to GABA_A receptors and HCAR1, respectively. Glutathione, in addition to its antioxidant role, also binds to ionotropic glutamate receptors in the synaptic cleft. Finally, we examined the hexosamine pathway and evaluated the effect of GlcNAc-modification on key proteins that regulate the other glucose destinations.

Streptozotocin-Induced Diabetes Mellitus in Neonatal Rats: An Insight into its Applications to Induce Diabetic Complications

BACKGROUND

Diabetic complications are the major contributor in the mortality of diabetic patients despite controlling blood glucose level. In the journey of new drug discovery, animal models have to play a major role. A large number of chemical-induced and genetically modified animal models have been investigated to induce diabetic complications but none of them was found to be mimicking the pathophysiology of the human. Therefore, the search and identification of the appropriate animal model become essential.

OBJECTIVE

In the present review, we have made an attempt to understand the pathophysiology of diabetic complication in the neonatal streptozotocin-diabetic rat model and tried to identify the targets for therapeutic agents. The review will help the researchers to explore the animal model to induce diabetic complications, to identify targets and further to find lead molecules for treatment or prevention of diabetic complications.

METHODS

We have compiled the available research work from 1974 by using prominent databases, organized the available information and analyzed the data to improve the understanding of the pathophysiology of streptozotocin-induced diabetic complications in neonates of rats.

RESULTS

The neonatal streptozotocin-diabetic rat model is frequently used and well-established animal model for type 2 diabetes mellitus. We have found that this model has been used to study the pathogenesis of various micro and macrovascular diabetic complications and also investigated for its effects on the liver, thymus gland, and brain. The underlying pathophysiology for complications had a resemblance to the human.

CONCLUSION

The neonatal streptozotocin-diabetic rat model may demonstrate symptomatic diabetic complications due to persistent hyperglycemia at the age of approximately 18-24 weeks. Critical interpretations of available research work showed that the researcher can explore split dose STZ (90- 100mg/kg b.w) model to induce Type 2 DM in neonates of rats at 2nd or 3rd postnatal day.

Neonatal hyperglycemia induces CXCL10/CXCR3 signaling and microglial activation and impairs long-term synaptogenesis in the hippocampus and alters behavior in rats

BACKGROUND

Hyperglycemia is common in extremely low gestational age newborns (ELGAN) and is associated with increased mortality and morbidity, including abnormal neurodevelopment. Hippocampus-mediated cognitive deficits are common in this population, but the specific effects of hyperglycemia on the developing hippocampus are not known.

METHODS

The objective of this study was to determine the acute and long-term effects of hyperglycemia on the developing hippocampus in neonatal rats using a streptozotocin (STZ)-induced model of hyperglycemia. STZ was injected on postnatal day (P) 2, and littermates in the control group were injected with an equivalent volume of citrate buffer. The acute effects of hyperglycemia on markers of oxidative stress, inflammatory cytokines, microglial activation, and reactive astrocytosis in the hippocampus were determined in the brain tissue collected on P6. The long-term effects on hippocampus-mediated behavior and hippocampal dendrite structure were determined on P90.

RESULTS

On P6, the transcript and protein expression of markers of oxidative stress and inflammatory cytokines, including the CXCL10/CXCR3 pathway, were upregulated in the hyperglycemia group. Histological evaluation revealed microglial activation and astrocytosis. The long-term assessment on P90 demonstrated abnormal performance in Barnes maze neurobehavioral testing and altered dendrite structure in the hippocampus of formerly hyperglycemic rats.

CONCLUSIONS

Neonatal hyperglycemia induces CXCL10/CXCR3 signaling, microglial activation, and astrocytosis in the rat hippocampus and alters long-term synaptogenesis and behavior. These results may explain the hippocampus-specific cognitive deficits common in ELGAN who experience neonatal hyperglycemia.

Neonatal hyperglycemia induces cell death in the rat brain

Several studies have examined neonatal diabetes, a rare disease characterized by hyperglycemia and low insulin levels that is usually diagnosed in the first 6 month of life. Recently, the effects of diabetes on the brain have received considerable attention. In addition, hyperglycemia may perturb brain function and might be associated with neuronal death in adult rats. However, few studies have investigated the damaging effects of neonatal hyperglycemia on the rat brain during central nervous system (CNS) development, particularly the mechanisms involved in the disease. Thus, in the present work, we investigated whether neonatal hyperglycemia induced by streptozotocin (STZ) promoted cell death and altered the levels of proteins involved in survival/death pathways in the rat brain. Cell death was assessed using FluoroJade C (FJC) staining and the expression of the p38 mitogen-activated protein kinase (p38), phosphorylated-c-Jun amino-terminal kinase (p-JNK), c-Jun amino-terminal kinase (JNK), protein kinase B (Akt), phosphorylated-protein kinase B (p-Akt), glycogen synthase kinase-3β (Gsk3β), B-cell lymphoma 2 (Bcl2) and Bcl2-associated X protein (Bax) protein were measured by Western blotting. The main results of this study showed that the metabolic alterations observed in diabetic rats (hyperglycemia and hypoinsulinemia) increased p38 expression and decreased p-Akt expression, suggesting that cell survival was altered and cell death was induced, which was confirmed by FJC staining. Therefore, the metabolic conditions observed during neonatal hyperglycemia may contribute to the harmful effect of diabetes on the CNS in a crucial phase of postnatal neuronal development.

DHEA supplementation to dexamethasone-treated rabbits alleviates oxidative stress in kidney-cortex and attenuates albuminuria

Our recent study has shown that dehydroepiandrosterone (DHEA) administered to rabbits partially ameliorated several dexamethasone (dexP) effects on hepatic and renal gluconeogenesis, insulin resistance and plasma lipid disorders. In the current investigation, we present the data on DHEA protective action against dexP-induced oxidative stress and albuminuria in rabbits. Four groups of adult male rabbits were used in the in vivo experiment: (1) control, (2) dexP-treated, (3) DHEA-treated and (4) both dexP- and DHEA-treated. Administration of dexP resulted in accelerated generation of renal hydroxyl free radicals (HFR) and malondialdehyde (MDA), accompanied by diminished superoxide dismutase (SOD) and catalase activities and a dramatic rise in urinary albumin/creatinine ratio. Treatment with DHEA markedly reduced dexP-induced oxidative stress in kidney-cortex due to a decline in NADPH oxidase activity and enhancement of catalase activity. Moreover, DHEA effectively attenuated dexP-evoked albuminuria. Surprisingly, dexP-treated rabbits exhibited elevation of GSH/GSSG ratio, accompanied by a decrease in glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities as well as an increase in glucose-6-phosphate dehydrogenase (G6PDH) activity. Treatment with DHEA resulted in a decline in GSH/GSSG ratio and glutathione reductase (GR) activity, accompanied by an elevation of GPx activity. Interestingly, rabbits treated with both dexP and DHEA remained the control values of GSH/GSSG ratio. As the co-administration of DHEA with dexP resulted in (i) reduction of oxidative stress in kidney-cortex, (ii) attenuation of albuminuria and (iii) normalization of glutathione redox state, DHEA might limit several undesirable renal side effects during chronic GC treatment of patients suffering from allergies, asthma, rheumatoid arthritis and lupus. Moreover, its supplementation might be particularly beneficial for the therapy of patients with glucocorticoid-induced diabetes.

METABOLISM AND CHEMILUMINESCENT ACTIVITY OF NEUTROPHILIC GRANULOCYTES IN PATIENTS WITH DIFFERENT SENSITIVITY TO ACETYLSALICYLIC ACID IN ACUTE CORONARY SYNDROME

Objective: to study the features of the chemiluminescent state and the activity of NAD (P) -depen- dent dehydrogenases in neutrophilic granulocytes of blood in patients with different sensitivity to acetylsalicylic acid (ACA) in acute coronary syndrome (ACS).Materials and methods: The study included 53 patients with ACS. Evaluation of resistance or sensitivity to ASA was performed in vitro by incubating platelet-rich plasma with adenosine diphosphate and ASA to determine the level of aggregation. The state of respiratory explosion of neutrophils was investigated by the method of chemiluminescence. The activity of enzymes in neutrophils was studied by the bioluminescent method.Results of the study: In patients with ACS-resistant ACS, the rate of synthesis of primary and secondary active forms of oxygen was reduced, and the index of luminol-dependent activation of neutrophils was reduced. The intensity of substrate stimulation of glycolysis and oxidation of glucose by the pentose phosphate pathway is increased.Conclusion: With resistance to ASA in patients with ACS, there are abnormalities in the metabolism and functional activity of neutrophils, which is of interest in studying the intercellular relationships of thrombus formation.

What has passed is prolog: new cellular and physiological roles of G6PD

G6PD deficiency has been the most pervasive inherited disorder in the world since having been discovered. G6PD has an antioxidant role by functioning as a major nicotinamide adenine dinucleotide phosphate (NADPH) provider to reduce excessive oxidative stress. NADPH can produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) mediated by NADPH oxidase (NOX) and nitric oxide synthase (NOS), respectively. Hence, G6PD also has a pro-oxidant role. Research in the past has focused on the enhanced susceptibility of G6PD-deficient cells or individuals to oxidative challenge. The cytoregulatory role of G6PD has largely been overlooked. By using a metabolomic approach, it is noted that upon oxidant challenge, G6PD-deficient cells will reprogram the GSH metabolism from regeneration to synthesis with exhaustive energy consumption. Recently, new cellular/physiologic roles of G6PD have been discovered. By using a proteomic approach, it has been found that G6PD plays a regulatory role in xenobiotic metabolism possibly via NOX and the redox-sensitive Nrf2-signaling pathway to modulate the expression of xenobiotic-metabolizing enzymes. Since G6PD is a key regulator responsible for intracellular redox homeostasis, G6PD deficiency can alter redox balance leading to many abnormal cellular effects such as the cellular inflammatory and immune response against viral infection. G6PD may play an important role in embryogenesis as G6PD-knockdown mouse cannot produce offspring and G6PD-deficient C. elegans with defective egg production and hatching. This array of findings indicates that the cellular and physiologic roles of G6PD, other than the classical role as an antioxidant enzyme, deserve further attention.

Diminished growth and lower adiposity in hyperglycemic very low birth weight neonates at 4 months corrected age

OBJECTIVE

Characterize the relationship between neonatal hyperglycemia and growth and body composition at 4 months corrected age (CA) in very low birth weight (VLBW) preterm infants.

STUDY DESIGN

A prospective study of VLBW appropriate-for-gestation infants (N=53). All blood glucose measurements in the first 14 days and nutritional intake and illness markers until discharge were recorded. Standard anthropometrics and body composition via air displacement plethysmography were measured near term CA and 4 months CA. Relationships between hyperglycemia and anthropometrics and body composition were examined using multivariate linear regression.

RESULTS

Infants with >5 days of hyperglycemia were lighter (5345 vs 6455 g, P⩽0.001), shorter (57.9 vs 60.9 cm, P⩽0.01), had smaller occipital-frontal head circumference (39.4 vs 42.0 cm, P⩽0.05) and were leaner (percent body fat 15.0 vs 23.8, P⩽0.01) at 4 months CA than those who did not have hyperglycemia, including after correcting for nutritional and illness factors.

CONCLUSIONS

Neonatal hyperglycemia in VLBW infants is associated with decreased body size and lower adiposity at 4 months CA independent of nutritional deficit, insulin use and illness. Downregulation of the growth hormone axis may be responsible. These changes may influence long-term growth and cognitive development.

Hyperglycemic Stress and Carbon Stress in Diabetic Glucotoxicity

Diabetes and its complications are caused by chronic glucotoxicity driven by persistent hyperglycemia. In this article, we review the mechanisms of diabetic glucotoxicity by focusing mainly on hyperglycemic stress and carbon stress. Mechanisms of hyperglycemic stress include reductive stress or pseudohypoxic stress caused by redox imbalance between NADH and NAD(+) driven by activation of both the polyol pathway and poly ADP ribose polymerase; the hexosamine pathway; the advanced glycation end products pathway; the protein kinase C activation pathway; and the enediol formation pathway. Mechanisms of carbon stress include excess production of acetyl-CoA that can over-acetylate a proteome and excess production of fumarate that can over-succinate a proteome; both of which can increase glucotoxicity in diabetes. For hyperglycemia stress, we also discuss the possible role of mitochondrial complex I in diabetes as this complex, in charge of NAD(+) regeneration, can make more reactive oxygen species (ROS) in the presence of excess NADH. For carbon stress, we also discuss the role of sirtuins in diabetes as they are deacetylases that can reverse protein acetylation thereby attenuating diabetic glucotoxicity and improving glucose metabolism. It is our belief that targeting some of the stress pathways discussed in this article may provide new therapeutic strategies for treatment of diabetes and its complications.