Homogenates Of Cerebral Cortex Research Articles

THE EFFECT OF SODIUM DEOXYCHOLATE AND TWЕЕN-20 ON THE ACTIVITY AND PROPERTIES OF NA+/K+-ATPase IN THE MIXED MEMBRANE FRACTION OF THE CEREBRAL CORTEX OF RATS

Interoduction. The present work extends the understanding of the activity of ouabain-sensitive (α2 and α3) and ouabain-resistant (α1) Na+/K+-ATPase isoforms in the mixed membrane fraction of rat cerebral cortex in the presence of various detergents. The aim of the study: to determine the activity of ouabain-sensitive (α2 and α3) and ouabain-resistant (α1) Na+/K+-ATPase isoforms by changing the concentration of Mg+2 ions in the incubation medium and using the detergents sodium deoxycholate and Tween-20. Material and methods. To determine Na+/K+-ATPase activity, we used the method of A. Kazennova et al. The reaction was triggered by adding ho-mogenate of cerebral cortex incubated with detergents; the samples were incubated for 30 minutes in a water bath at 370 C. The activity of ouabain-sensitive isoforms was determined by adding 200 μmol of ouabain to the incubation mixture. The activity of ouabain-sensitive isoforms was deter-mined by adding 200 μmol ouabain to the incubation mixture, and the activity of ouabain-resistant isoforms was determined as the difference between the total Na+/K+-ATPase activity and the activity of ouabain-sensitive isoforms. ATPase activity was determined by inorganic phosphate (Pi) increment as the difference between total ATPase activity, magnesium ATPase activity, in reaction with ammonium molybdate and tin chloride in the presence of ascorbic acid as a reducing agent. Results. At optimal concentrations of detergents Dox-Na (1.25 mg/mL) and Tween-20 (6.5 mg/mL), both ouabain-sensitive and ouabain-resistant Na+/K+-ATPase isoforms are characterized by normal activity dynamics from the concentration of Mg2+ ions. Consequently, the use of detergents at given concentrations does not change the ability of enzymes to conformational rearrangements during the reaction cycle. It was found that both used detergents allow to reveal a significant percentage of latent activity of ouabain-sensitive (α2 and α3) and ouabain-resistant (α1) Na+/K+-ATPase isoforms in the mixed mebran fraction of the cerebral cortex of rats. Conclusion. The study of Mg2+-dependent properties revealed a similar character of the curves of dependence of enzyme activity on the concentra-tion of Mg2+ in the incubation medium for all Na+/K+-ATPase isoforms studied

Effects of curcumin and melatonin treatment in the cerebral cortex of adult rats.

The study investigated the effect of exogenous melatonin and (or) curcumin treatment on the cerebral cortex of adult rats. In this context, malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH), superoxide dismutase (SOD), nuclear factor E2-related factor 2 (Nrf2) and SIRT2 protein expression were examined. A total of 30 Wistar albino rats involved in the study were randomly divided into five groups. Over 30 days, the control groups received phosphate-buffered saline or dimethyl sulfoxide injections, and the treatment groups received melatonin, curcumin, or a combination of melatonin and curcumin injections. In the cerebral cortex homogenates, the MDA, GSH, and sum of NO were respectively determined by the thiobarbituric acid, modified Ellman and Griess test methods. The SOD and Nrf2 levels were examined using the ELISA method and SIRT2 protein expression using the Western blot technique. The study found that both melatonin and curcumin treatments significantly reduced lipid peroxidation and SIRT2 protein expression levels (p < 0.05) and increased the Nrf2 level in the cytoplasm (p < 0.05). The study revealed that curcumin and melatonin treatments reduced MDA and SIRT2 protein expression level and increased intracellular Nrf2, GSH, and SOD in the cortex tissue. We also found that the combined melatonin and curcumin treatment produced no synergistic effect.

Стимулювання системи протеїназа-інгібітор протеїназ у результаті імерсійної гіпотермії

The effect of immersion hypothermia (IН) on proteolysis activity in adult male rats, which was performed at 0 °C for 5 min in the “forced swimming” test, studied; the body temperature decreased to 27.5 ± 0.5°C. In blood serum and non-nuclear fractions of homogenates of cerebral cortex, hypothalamus, cerebellum, brainstem, lungs, heart, liver and kidneys tissues were determined the total proteinase activity (TPA), non-trypsin-like proteinases (NTPs), such as chymase, prostate-specific antigen, partially tonin, kallikrein rK9, as well as trypsin-inhibitory activity of α-1-proteinase inhibitor (α-1-PI), α-2-macroglobulin (α-2-MG) by highly sensitive (10-9–10-10 g) enzymatic methods. It is noted that IH led to the TPA increase in all studied tissues (4-84 times), which corresponds to the psycho-emotional effects and the phenomenon of hormesis. After 24 h, TPA decreased, remaining above the control level, and in the kidneys increased further (90 times). NTLP activity as a result of IH increased in blood serum and cerebellum, decreased in the hypothalamus, and after 24 h increased further in serum (7 times), cerebellum, and heart. The activity of α-1-PI also increased in the brainstem, lungs, heart and kidneys, and decreased after 24 h in serum below the control level, and in the brainstem remained high, protecting against proteolytic attack. The activity of α-2-MG increased in the hypothalamus, heart, and cerebral cortex, maximum in the brainstem (2-5 times), and after 24 h - more significantly (24 times), but there were no changes in the cerebellum, where its initial level is the biggest. Thus, the development of IG as a result of swimming in cold water for 5 min at 0oC has a stimulating effect on the body and leads to a significant activation of the reactions of limited proteolysis.

Effect of chlorogenic acid plus donepezil on critical neurocortical enzyme activities, inflammatory markers, and synaptophysin immunoreactivity in scopolamine-assaulted rats, supported by multiple ligand simultaneous docking.

The effect of chlorogenic acid (a natural phenolic acid ubiquitous in plant foods) on selected therapeutic properties of donepezil (DON) in a scopolamine (SCOP)-induced rat model of amnesia was the focus of this study. Adult albino (Wister strain) rats were allocated into five groups (n=11) consisting of control, SCOP, SCOP + chlorogenic acid (CGA), SCOP + DON, and SCOP + CGA + DON for 7 days. Post-treatment, the rat brain cerebral cortex homogenate was assayed for cholinesterase and monoamine oxidase activities. Also, the reactive oxygen species, total thiol and nitric oxide contents, alongside catalase, and superoxide dismutase activities were determined. Routine histology for neuronal and glial cells as well as synaptophysin immunoreactivity was also carried out on the cerebral cortex. Thereafter, multiple ligand simultaneous docking was carried out for DON and CGA at the active sites of AChE and BChE. The results revealed that the biochemical parameters, glial cells, and synaptophysin immunoreactivity were significantly impaired in the cerebral cortex of scopolamine-treated rats. However, impaired butyrylcholinesterase and monoamine oxidase activity, together with antioxidant, glial cells, and synaptophysin levels were significantly ameliorated in scopolamine-treated rats administered DON + CGA compared to donepezil alone. The docking of both DON and CGA at the active sites of AChE or BChE showed higher binding energy to both enzymes compared to individual interactions of either DON or CGA. Hence, this study has been able to show that CGA could improve some of the therapeutic effects of DON, which could broaden the therapeutic spectrum of this drug. PRACTICAL APPLICATIONS: This study showed that chlorogenic acid (a major phenolic acid found in plant foods such as coffee) modulated some of the therapeutic properties of donepezil (an anticholinesterase drug used in the treatment of mild-to-moderate Alzheimer's disease). The combinations elicited better anti-butyrylcholinesterase, antimonoamine oxidase, and antioxidant properties, thus presenting this food-drug interaction as potentially able to offer better therapeutic properties.

Hypoxia Inducible Factor is partially involved in mitochondrial and metabolic responses to hypoxia in rats DEMAREST Maud 1, MARCOUILLER François 1, SOLIZ Jorge 1, JOSEPH Vincent 11 Institut universitaire de cardiologie et de pneumologie, Université Laval, Québec

High altitude environments present many constraints for mammals, the most well‐known being the lack of oxygen or hypoxia. Nevertheless, several ecological reports show that mice (Mus musculus) unlike rats (Rattus norvegicus) are present above 4000m1 although they are not native to this environment. The associated general hypothesis is that mice are pre‐adapted to high altitude environments. There are also differences in mitochondrial2, ventilatory and metabolic3 responses to hypoxia between these two species. One of the mechanisms involved in many of these responses is the hypoxia‐inducible factor HIF, which helps maintain the cell's oxygen homeostasis. What precisely are the different roles of HIF in mitochondrial, ventilatory, and metabolic responses to hypoxia in rats and mice, two species more or less adapted to high‐altitude environments? Does the pharmacological stabilization of HIF in normoxia mimic the responses observed in hypoxia? Conversely, does blocking HIF in hypoxia suppress these same responses? We measured the ventilatory and metabolic responses (whole body plethysmography) of rats (SD) and mice (FVB) under the following conditions: (i) 6h normoxia (21% O2); (ii) 6h hypoxia (10% O2); (iii) 6h normoxia with injection of deferoxamine, a HIF stabilizer (200mg/kg) and (iv) 6h hypoxia with injection of 2‐methoxyestradiol, a HIF blocker (5mg/kg). In addition, we evaluated mitochondrial respiration in homogenates of liver and cerebral cortex, two organs sensitive to hypoxia. Our preliminary results show that hypoxia increases ventilation and reduces metabolism and complex I efficiency in the cerebral cortex. Furthermore, pharmacological stabilization of HIF has no effect on the ventilatory response, but seems to mimic some mitochondrial and metabolic responses to hypoxia, whereas blocking HIF has no effect on these same responses. If in mice blocking HIF in hypoxia reduces the amplitude of the observed responses, our data will demonstrate fundamental differences in the mechanisms of responses to hypoxia between these two species that would strongly support our general hypothesis.

Neuroprotective role of Allium cepa and Allium sativum on Hippocampus, striatum and Cerebral cortex in Wistar rats

Natural products are gaining much importance in light of the serious side effects posed by drugs of chemical origin. High intake of foods rich in antioxidants reduces the risk of neurodegenerative disorders. Traditionally, Allium sativum L.(garlic) and Allium cepa. L (onion) has received considerable attention for their therapeutic benefits around the globe. The present study assesses the free radical scavenging role of Allium sativum and Allium cepa in cerebral cortex, striatum, and hippocampus. Adult wistar rats of either sex were grouped as control group (Group I) treated with normal saline and the two experimental group were treated with the aqueous bulbous extracts of dehydrated Allium sativum (Group II) and Allium cepa (Group III) was considered as treated groups. Homogenates of hippocampus, striatum and cerebral cortex were analyzed for biochemical and neuronal analysis. LD50 value of these extracts in rats was found at a dose of 500 mg/kg BW. A Significant decline (P&lt;0.05) in the MDA level was observed in the hippocampus, striatum and cerebral cortex in group II when compared to group III. Total antioxidant level, GSH, SOD level was significantly high (P&lt;0.001) in the treated groups. Neuronal increase was significant in Group II (P &lt; 0.01) when compared to Group III. Allium sativum and Allium cepa was found to have a challenging role in hampering oxidative stress in Hippocampus, striatum and cerebral cortex, the target regions in neurological disorders. However, ample number of studies are required to establish their mechanism of action as a progression to clinical approach.

Effects of resveratrol on alterations in cerebrum energy metabolism caused by metabolites accumulated in type I citrullinemia in rats.

We investigated the in vitro effects of citrulline (0.1, 2.5 and 5.0mM) and ammonia (0.01, 0.1 and 1.0mM), and the influence of resveratrol (0.01mM, 0.1mM and 0.5mM) on pyruvate kinase, citrate synthase, succinate dehydrogenase (SDH), complex II, and cytochrome c oxidase activities in cerebral cortex, cerebellum and hippocampus homogenates of 60-day-old male Wistar rats. Results showed that 2.5 and 5.0mM citrulline decreased pyruvate kinase activity in cerebral cortex and, at a concentration of 5.0mM, increased its activity in hippocampus. Additionally, 5.0mM citrulline increased citrate synthase activity in the cerebellum of rats. Citrulline (5.0mM) reduced complex II and cytochrome c oxidase activities in cerebral cortex and hippocampus. With regard to ammonia, at 0.1 and 1.0mM, decreased complex II activity in cerebral cortex and at 1.0mM decreased its activity in cerebellum and hippocampus. Ammonia (1.0mM) also decreased cytochrome c oxidase activity in cerebral cortex and cerebellum of rats. Resveratrol was able to prevent most of the alterations caused by these metabolites in the biomarkers of energy metabolism measured in the cerebrum of rats. Data suggest that these alterations in energy metabolism, caused by citrulline and ammonia, are probably mediated by the generation of free radicals, which can in turn be scavenged by resveratrol.

POTENTIAL PROTECTIVE EFFECTS OF ANGIOTENSIN II TYPE 1 RECEPTOR BLOCKADE IN ALZHEIMER RAT MODEL

Background: Alzheimer disease (AD) and Alzheimer type dementia (ATD) represent major health problem in aged population. AD is characterized by memory impairment, exaggerated oxidative stress and decrease antioxidant capacity. Angiotensin II and angiotensin II type 1 and type 2 receptors (ATR1 and ATR2) are incriminated in the pathogenesis of AD.Aim of the work: This study was carried out to investigate the effect of angiotensin II type 1 receptor blockade on memory function in AlCl3-induced Alzheimer in rats. Materials and methods: Thirty animals in this study were divided into five equal groups. Group1: control rats. Group II: Alzheimer model, the rats were intraperitoneally injected with 40 mg / kilogram body AlCl3 for 4 weeks group III: ATR1 blocker-treated AD-group: animals were injected telmisartan in a dose of 1mg/kg. by oral gavage for 8 weeks and for the last 4 weeks were injected AlCl3. Group 4: Donepezil-treated AD-group: rats were given Donepezil 5 mg/kg orally for 8 weeks and for the last 4 weeks were injected AlCl3. Group 5: ATR1 blocker-donepezil treated AD group. After the 8 weeks, animals were suspected to short term memory testing using the NovelObject Recognition test interpreting the discrimination index (DI), Recognition index (RI), frequency of exploration and locomotor activity. Malondialdehyde (MDA), Glutathione (GSH) and glutamate contents of cerebral cortex and hippocampus homogenates were biochemically assayed. Results: AlCl3-treated group showed impaired short-termmemory indices and locomotor activity with increased MDA and decreased GSH as well as glutamate content in cerebral cortex and hippocampus. ATR1 blocker-treated group showed significant improvement in memory function, decreased MDA and increased GSH as well as decreased glutamate content. In ATR1 blocker plus donepezil -treated group the effects of both drugs were additive and parallel. Conclusion: ATR1 blockade improved memory function in ATD induced by AlCl3 injection in rats and exerts antioxidant and antiexcitotoxic effects.

Catalase activity is heterogeneous among tissues in the Weddell seal, and consistent with patterns of tissue perfusion during diving

Hypoxia/ischemia that occurs when tissue blood flow is compromised, and subsequent reoxygenation/reperfusion when it is then recovered, is expected to deliver an oxidative stress insult to cells. However, many species are naturally tolerant of hypoxic and ischemic conditions. Weddell seals routinely restrict blood flow to certain peripheral tissues to conserve oxygen during extended dives, yet their tissues do not demonstrate markers of damage from oxidative stress. Understanding how Weddell seals cope with scenarios that generate oxidative stress in terrestrial mammals has the potential to inform human therapies and suggest mechanisms of protection against ischemic and hypoxic injury. Seals have been shown to have higher tissue antioxidant activities than terrestrial mammals generally, however degree of ischemia varies by tissue, and the degree to which antioxidant protective mechanisms track this variation is unknown. This study hypothesized that if the antioxidant catalase is a component of protection against ischemia/reperfusion in diving seals, that catalase activity would correlate with degree of hypoperfusion expected in different tissues. Catalase activity was measured in the right ventricle, cerebral cortex, and kidney homogenates of five seal adults, five seal pups, and compared to similar measurements in six adult sheep. Protein abundance was measured in the same tissues by western blot, and mRNA expression was measured with qPCR using species‐specific primers. In both species, catalase activity was highest in kidney and lowest in brain. However, kidney catalase activity was 71% higher in the diving seal than in terrestrial sheep (p = 0.00003), consistent with the observation that the seal kidney experiences the greatest degree of blood flow reduction during extended diving. Blood flow is only marginally reduced in the diving seal's heart, but maintained in the brain during submergence. As predicted, catalase activity in the heart was also moderately higher in seals than in sheep (33%, p = 0.04), whereas brain catalase activity was comparable between species (p = 0.8). Western immunoblot and qPCR results supported the tissue‐specific activity differences, demonstrating that catalase protein and mRNA levels were highest in kidney and lowest in brain. These results are consistent with the interpretation that tissues most exposed to repetitive hypoxemia/reoxygenation in seals do have proportionally higher expression of catalase, resulting in higher antioxidant activity. However protein and transcript levels did not align with differences in enzyme activity between seals and sheep, suggesting that further research is required to elucidate whether Weddell seal catalase is functionally different than terrestrial species.Support or Funding InformationFunding by the National Science Foundation and the American Physiological Society's Undergraduate Summer Research Fellowship program.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

In vitro effect of globotriaosylceramide on electron transport chain complexes and redox parameters.

Fabry disease (FD) is an X-linked inherited disease and occurs due to mutations in GLA gene that encodes the α-galactosidase enzyme. Consequently, there is an accumulation of enzyme substrates, namely globotriaosylceramide (GB3). FD is a multisystemic disease, caused by storage of GB3 in vascular endothelia, with significant renal, cardiac and vascular involvement. The aim of this work was to evaluate the in vitro effect of GB3 on electron transport chain complexes (ETC) and redox parameters. Biochemical biomarkers were determined in homogenates of cerebral cortex, kidneys and liver of Wistar rats in the presence or absence of GB3 at concentrations of 3, 6, 9 and 12 mg/L. We found that GB3 caused an increase of ETC complexes II and IV activities, increased production of reactive species and decreased superoxide dismutase enzyme activity in homogenates of cerebral cortex. As well also increased production of reactive species and superoxide dismutase activity in kidney homogenates. The results obtained in our work suggest that GB3 interferes in ETC complexes II and IV activities, however, the magnitude of this increase seems to be too low to present a physiologically importance. However, the imbalance in cellular redox state indicating that these alterations may be involved in the pathophysiology of FD, mainly in renal and cerebral manifestations.

A Method of Analysis of the Functional Activity of P-Glycoprotein in the Blood–Brain Barrier

This article describes a method for testing the functional activity of the transporter protein P-glycoprotein (Pgp) in the blood–brain barrier in Wistar rats. This method is based on the study of the pharmacokinetics of fexofenadine, a marker substrate of Pgp, after its single intravenous administration at a dose of 10 mg/kg. Quantitative determination of fexofenadine in rat blood plasma and homogenate of the rat cerebral cortex was performed by high performance liquid chromatography with ultraviolet detection. To assess the permeability of the blood–brain barrier and Pgp activity, we proposed to calculate the area under the fexofenadine concentration in the cerebral cortex–time curve (AuC0−t(brain)), which reflects the total amount of fexofenadine in the brain. The adequacy of the developed method was confirmed when fexofenadine was administered to rats in the presence of an inducer and an inhibitor of the transporter protein.

Dynamics of changes in the content of thyroid hormones and some neurotransmitters in brain of rats with experimental Alzheimer’s disease

Objective: Alzheimer's disease is one of the most common neurodegenerative diseases, and mechanisms of its development have been studied for many years. The aim of the research was to study the content of thyroid-stimulating hormone (TSH), thyroid hormones and tau protein in the blood serum, as well as the content of thyroid hormones and some neurotransmitters in the cerebral cortex in the dynamics of experimental Alzheimer’s disease in rats. Materials and methods. The experiment was performed on 45 WAG rats, which were divided into 3 groups. The first group was the control one. Animals from the second and third groups were intraperitoneally administered with scopolamine for 14 and 27 days, which led to the development of Alzheimer's disease. Brain homogenate was prepared. Concentrations of T3, T4 in blood serum and homogenates of the cerebral cortex, as well as TSH and tau protein in serum, were determined by ELISA. Determination of the content of neurotransmitter amino acids (aspartate and glutamate) was carried out by thin-layer chromatography. The content of dopamine and norepinephrine in the cerebral cortex homogenate was determined by column chromatography, and acetylcholine levels were measured by spectrophotometry. Morphological examination included staining of brain tissue with congo-rot + hematoxylin. Results. It was established that in cerebral cortex homogenates of rats with experimental Alzheimer’s disease the T3 content was reduced, and T4 levels were similar to rats of the control group, which in combination with the normal concentration of thyroid hormones in blood serum indicates the development of local hypothyroidism in the cerebral cortex. In rats with Alzheimer's disease, glutamic and aspartic acid levels were increased against the background of GABA reduction. There was also a decrease in the levels of noradrenaline and dopamine in the cerebral cortex homogenates, which contributes to the abnormal energy metabolism and impaired cognitive functions. Morphological study demonstrated the presence of congophilic masses in the brain tissue and in the walls of small arteries with the development of brain atrophy. Conclusions. Alzheimer's disease caused by the administration of scopalamine is characterized by the development of local hypothyroidism in the cerebral cortex, an increase in the level of glutamic and aspartic acids with a decrease in GABA, a decrease in the level of dopamine and norepinephrine in the cerebral cortex.

Chlorogenic Acid Prevents Alcohol-induced Brain Damage in Neonatal Rat.

The present investigation evaluates the neuroprotective effect of chlorogenic acid (CA) in alcohol-induced brain damage in neonatal rats. Ethanol (12 % v/v, 5 g/kg) was administered orally in the wistar rat pups on postnatal days (PD) 7-9. Chlorogenic acid (100 and 200 mg/kg, p.o.) was administered continuously from PD 6 to 28. Cognitive function was estimated by Morris water maze (MWM) test. However, activity of acetylcholinesterase, inflammatory mediators, parameters of oxidative stress and activity of caspase-3 enzyme was estimated in the tissue homogenate of cerebral cortex and hippocampus of ethanol-exposed pups. It has been observed that treatment with CA attenuates the altered cognitive function in ethanol-exposed pups. There was a significant decrease in the activity of acetylcholinesterase in the CA treated group compared to the negative control group. However, treatment with CA significantly ameliorates the increased oxidative stress and concentration of inflammatory mediators in the brain tissues of ethanol-exposed pups. Activity of caspase-3 enzyme was also found significantly decreased in the CA treated group compared to the negative control group. The present study concludes that CA attenuates the neuronal damage induced in alcohol exposed neonatal rat by decreasing the apoptosis of neuronal cells.

Bioenergetics dysfunction, mitochondrial permeability transition pore opening and lipid peroxidation induced by hydrogen sulfide as relevant pathomechanisms underlying the neurological dysfunction characteristic of ethylmalonic encephalopathy

Hydrogen sulfide (sulfide) accumulates at high levels in brain of patients with ethylmalonic encephalopathy (EE). In the present study, we evaluated whether sulfide could disturb energy and redox homeostasis, and induce mitochondrial permeability transition (mPT) pore opening in rat brain aiming to better clarify the neuropathophysiology of EE. Sulfide decreased the activities of citrate synthase and aconitase in rat cerebral cortex mitochondria, and of creatine kinase (CK) in rat cerebral cortex, striatum and hippocampus supernatants. Glutathione prevented sulfide-induced CK activity decrease in the cerebral cortex. Sulfide also diminished mitochondrial respiration in cerebral cortex homogenates, and dissipated mitochondrial membrane potential (ΔΨm) and induced swelling in the presence of calcium in brain mitochondria. Alterations in ΔΨm and swelling caused by sulfide were prevented by the combination of ADP and cyclosporine A, and by ruthenium red, indicating the involvement of mPT in these effects. Furthermore, sulfide increased the levels of malondialdehyde in cerebral cortex supernatants, which was prevented by resveratrol and attenuated by glutathione, and of thiol groups in a medium devoid of brain samples. Finally, we verified that sulfide did not alter cell viability and DCFH oxidation in cerebral cortex slices, primary cortical astrocyte cultures and SH-SY5Y cells. Our data provide evidence that bioenergetics disturbance and lipid peroxidation along with mPT pore opening are involved in the pathophysiology of brain damage observed in EE.

Accumulation of lactate in the rat brain during hyperammonaemia is not associated with impaired mitochondrial respiratory capacity

In acute liver failure (ALF) cerebral oedema and high intracranial pressure (ICP) are potentially deadly complications. Astrocytes cultured in ammonia have shown mitochondrial dysfunction and in rat models of liver failure, de novo lactate production in the brain has been observed and has led to a hypothesis of compromised brain metabolism during ALF. In contrast, normal lactate levels are found in cerebral microdialysate of ALF patients and the oxygen: glucose ratio of cerebral metabolic rates remains normal. To investigate this inconsistency we studied the mitochondrial function in brain tissue with respirometry in animal models of hyperammonaemia. Wistar rats with systemic inflammation induced by lipopolysaccharide or liver insufficiency induced by 90% hepatectomy were given ammonium or sodium acetate for 120min. A cerebral cortex homogenate was studied with respirometry and substrates of the citric acid cycle, uncouplers and inhibitors of the mitochondrial complexes were successively added to investigate the mitochondrial function in detail. In a separate dose-response experiment cortex from healthy rats was incubated for 120min in ammonium acetate in concentrations up to 80mM prior to respirometry. Hyperammonaemia was associated with elevated ICP and increased tissue lactate concentration. No difference between groups was found in total respiratory capacity or the function of individual mitochondrial complexes. Ammonium in concentrations of 40 and 80mM reduced the respiratory capacity in vitro. In conclusion, acute hyperammonaemia leads to elevated ICP and cerebral lactate accumulation. We found no indications of impaired oxidative metabolism in vivo but only in vitro at extreme concentrations of ammonium.

Alterations in behaviour, cerebral cortical morphology and cerebral oxidative stress markers following aspartame ingestion

ObjectiveThe study evaluated changes in open field behaviours, cerebral cortical histomorphology and biochemical markers of oxidative stress following repeated administration of aspartame in mice. MethodologyAdult mice were assigned into five groups of twelve each. Vehicle (distilled water), or aspartame (20, 40, 80 and 160mg/kg body weight) were administered orally for 28days. Horizontal locomotion, rearing and grooming were assessed after the first and last dose of aspartame. Sections of the cerebral cortex were processed and stained for general histology, and also examined for neuritic plaques using the Bielschwosky’s protocol. Glial fibrillary acidic protein (GFAP) and neuron specific enolase (NSE) immunoreactivity were assessed using appropriate antibodies. Aspartate and antioxidant levels were also assayed from cerebral cortex homogenates. Data obtained were analysed using descriptive and inferential statistics. ResultsBody weight and food consumption decreased significantly with aspartame consumption. Locomotion, rearing and grooming increased significantly after first dose, and with repeated administration of aspartame. Histological changes consistent with neuronal damage were seen at 40, 80 and 160mg/kg. Neuritic plaque formation was not evident; while GFAP-reactive astrocytes and NSE-reactive neurons increased at 40 and 80mg/kg but decreased at 160mg/kg. Superoxide dismutase and nitric oxide increased with increasing doses of aspartame, while aspartate levels showed no significant difference. ConclusionThe study showed morphological alterations consistent with neuronal injury and biochemical changes of oxidative stress. These data therefore supports the need for caution in the indiscriminate use of aspartame as a non-nutritive sweetener.

Evaluation of Oxidative Stress Parameters and Energy Metabolism in Cerebral Cortex of Rats Subjected to Sarcosine Administration.

Sarcosine is an N-methyl derivative of the amino acid glycine, and its elevation in tissues and physiological fluids of patients with sarcosinemia could reflect a deficient pool size of activated 1-carbon units. Sarcosinemia is a rare inherited metabolic condition associated with mental retardation. In the present study, we investigated the acute effect of sarcosine and/or creatine plus pyruvate on some parameters of oxidative stress and energy metabolism in cerebral cortex homogenates of 21-day-old Wistar rats. Acute administration of sarcosine induced oxidative stress and diminished the activities of adenylate kinase, GAPDH, complex IV, and mitochondrial and cytosolic creatine kinase. On the other hand, succinate dehydrogenase activity was enhanced in cerebral cortex of rats. Moreover, total sulfhydryl content was significantly diminished, while DCFH oxidation, TBARS content, and activities of SOD and GPx were significantly enhanced by acute administration of sarcosine. Co-administration of creatine plus pyruvate was effective in the prevention of alterations provoked by sarcosine administration on the oxidative stress and the enzymes of phosphoryltransfer network. These results indicate that acute administration of sarcosine may stimulate oxidative stress and alter the energy metabolism in cerebral cortex of rats. In case these effects also occur in humans, they may contribute, along with other mechanisms, to the neurological dysfunction of sarcosinemia, and creatine and pyruvate supplementation could be beneficial to the patients.

Native CB1 receptor affinity, intrinsic activity and accumbens shell dopamine stimulant properties of third generation SPICE/K2 cannabinoids: BB-22, 5F-PB-22, 5F-AKB-48 and STS-135

In order to investigate the in vivo dopamine (DA) stimulant properties of selected 3rd generation Spice/K2 cannabinoids, BB-22, 5F-PB-22, 5F-AKB-48 and STS-135, their in vitro affinity and agonist potency at native rat and mice CB1 receptors was studied. The compounds bind with high affinity to CB1 receptors in rat cerebral cortex homogenates and stimulate CB1-induced [35S]GTPγS binding with high potency and efficacy. BB-22 and 5F-PB-22 showed the lowest Ki of binding to CB1 receptors (0.11 and 0.13 nM), i.e., 30 and 26 times lower respectively than that of JWH-018 (3.38 nM), and a potency (EC50, 2.9 and 3.7 nM, respectively) and efficacy (Emax, 217% and 203%, respectively) as CB1 agonists higher than JWH-018 (EC50, 20.2 nM; Emax, 163%). 5F-AKB-48 and STS-135 had higher Ki for CB1 binding, higher EC50 and lower Emax as CB1 agonists than BB-22 and 5F-PB-22 but still comparatively more favourable than JWH-018.The agonist properties of all the compounds were abolished or drastically reduced by the CB1 antagonist/inverse agonist AM251 (0.1 μM). No activation of G-protein was observed in CB1-KO mice. BB-22 (0.003–0.01 mg/kg i.v.) increased dialysate DA in the accumbens shell but not in the core or in the medial prefrontal cortex, with a bell shaped dose–response curve and an effect at 0.01 mg/kg and a biphasic time-course. Systemic AM251 (1.0 mg/kg i.p.) completely prevented the stimulant effect of BB-22 on dialysate DA in the NAc shell. All the other compounds increased dialysate DA in the NAc shell at doses consistent with their in vitro affinity for CB1 receptors (5F-PB-22, 0.01 mg/kg; 5F-AKB-48, 0.1 mg/kg; STS-135, 0.15 mg/kg i.v.). 3rd generation cannabinoids can be even more potent and super-high CB1 receptor agonists compared to JWH-018. Future research will try to establish if these properties can explain the high toxicity and lethality associated with these compounds.

Evidence that 3-hydroxy-3-methylglutaric and 3-methylglutaric acids induce DNA damage in rat striatum.

3-Hydroxy-3-methylglutaryl-CoA lyase (HL) deficiency is a rare autosomal recessive disorderaffecting the final step of leucine degradation and ketogenesis and biochemically characterized by the predominant accumulation of 3-hydroxy-3-methylglutaric (HMG) and 3-methylglutaric (MGA) acids in biological fluids and tissues of affected patients. Considering that previous studies reported that HMG and MGA have pro oxidant properties, the present study evaluated the ex vivo and in vitro effects of HMG and MGA on frequency and index of DNA damage in cerebral cortex and striatum of young rats. The ex vivo effects of both organic acids on 8-hydroxy-2'-deoxyguanosine (OHdG) levels and their in vitro effects on 2',7'-dichlorofluorescin (DCFH) oxidation and glutathione (GSH) concentrations in rat striatum were also determined. We also investigated the ex vivo effects of both organic acids on 8-hydroxy-2'-deoxyguanosine (OHdG) levels in rat striatum. In the ex vivo experiments, DNA damage was determined in striatum homogenates prepared 30min after a single intrastriatal administration of HMG or MGA. On the other hand, the in vitro evaluation was performed after an incubation of rat cerebral cortex or striatum homogenates or slices in the presence of HMG or MGA during 1h at 37°C. We observed that the intrastriatal administration of HMG and MGA increased the frequency and the index of DNA damage, as well as OHdG staining in rat striatum. We also verified that MGA, but not HMG, increased DNA damage frequency and index in vitro in striatum of rats. In contrast, no alterations were verified in vitro in cerebral cortex. Finally, we found that HMG and MGA increased DCFH oxidation and decreased GSH concentrations in rat striatum. Therefore, it may be presumed that DNA damage provoked by HMG and MGA possibly via reactive species generation is involved, at least in part, in the pathophysiology of brain injury, particularly in the striatum of HL-deficient patients.

Creatine and pyruvate prevent the alterations caused by tyrosine on parameters of oxidative stress and enzyme activities of phosphoryltransfer network in cerebral cortex of Wistar rats.

Tyrosine accumulates in inborn errors of tyrosine catabolism, especially in tyrosinemia type II. In this disease caused by tyrosine aminotransferase deficiency, eyes, skin, and central nervous system disturbances are found. In the present study, we investigated the chronic effect of tyrosine methyl ester (TME) and/or creatine plus pyruvate on some parameters of oxidative stress and enzyme activities of phosphoryltransfer network in cerebral cortex homogenates of 21-day-old Wistar. Chronic administration of TME induced oxidative stress and altered the activities of adenylate kinase and mitochondrial and cytosolic creatine kinase. Total sulfhydryls content, GSH content, and GPx activity were significantly diminished, while DCFH oxidation, TBARS content, and SOD activity were significantly enhanced by TME. On the other hand, TME administration decreased the activity of CK from cytosolic and mitochondrial fractions but enhanced AK activity. In contrast, TME did not affect the carbonyl content and PK activity in cerebral cortex of rats. Co-administration of creatine plus pyruvate was effective in the prevention of alterations provoked by TME administration on the oxidative stress and the enzymes of phosphoryltransfer network, except in mitochondrial CK, AK, and SOD activities. These results indicate that chronic administration of TME may stimulate oxidative stress and alter the enzymes of phosphoryltransfer network in cerebral cortex of rats. In case this also occurs in the patients affected by these disorders, it may contribute, along with other mechanisms, to the neurological dysfunction of hypertyrosinemias, and creatine and pyruvate supplementation could be beneficial to the patients.