Post-mortem interval estimative through determination of catalase and Δ-aminolevulinate dehydratase activities in hepatic, renal, skeletal muscle and cerebral tissues of Swiss mice.

Purpose: Determining the post-mortem interval (PMI) is one of the challenging tasks in forensic science due to the lack of quick and inexpensive methods. Our objective is to develop innovative and alternative means for PMI evaluation. Methods: The relationship between PMI and enzymatic modifications in mice tissues was described. After being sacrificed, Swiss mice were randomly divided into groups according to the time elapsed since death. The activities of catalase (CAT) and δ-aminolevulinate dehydratase (δ-ALA-D) were determined in hepatic, renal, skeletal muscle and cerebral tissues. Results: CAT activity increased in kidney and brain 6 h after death and this increase remained for up to 24 h in the brain and 48 h in the kidney. δ-ALA-D had its activity decreased in the liver and kidneys in 6 h. In the skeletal muscle, δ-ALA-D activity was reduced only 48 h after death. Conversely, an increase on δ-ALA-D activity was observed in the brain at 6 h, followed by its decrease at 24 and 48 h. Conclusion: With the association of this set of results, it is possible to provide an estimate of PMI. Additionally, these results can be used as an auxiliary parameter associated with other methods to estimate PMI.

Senescence-associated-ß-galactosidase staining following traumatic brain injury in the mouse cerebrum.

Primary and secondary traumatic brain injury (TBI) can cause tissue damage by inducing cell death pathways including apoptosis, necroptosis, and autophagy. However, similar pathways can also lead to senescence. Senescent cells secrete senescence-associated secretory phenotype proteins following persistent DNA damage response signaling, leading to cell disorders. TBI initially activates the cell cycle followed by the subsequent triggering of senescence. This study aims to clarify how the mRNA and protein expression of different markers of cell cycle and senescence are modulated and switched over time after TBI. We performed senescence-associated-ß-galactosidase (SA-ß-gal) staining, immunohistochemical analysis, and real-time PCR to examine the time-dependent changes in expression levels of proteins and mRNA, related to cell cycle and cellular senescence markers, in the cerebrum during the initial 14 days after TBI using a mouse model of controlled cortical impact (CCI). Within the area adjacent to the cerebral contusion after TBI, the protein and/or mRNA expression levels of cell cycle markers were increased significantly until 4 days after injury and senescence markers were significantly increased at 4, 7, and 14 days after injury. Our findings suggested that TBI initially activated the cell cycle in neurons, astrocytes, and microglia within the area adjacent to the hemicerebrum contusion in TBI, whereas after 4 days, such cells could undergo senescence in a cell-type-dependent manner.

Oxidative stress mediated the inhibition of cerebral creatine kinase activity in silver catfish fed with aflatoxin B1-contaminated diet.

Aflatoxin B1 (AFB1) is an environmental toxicant and neurotoxic compound that induces the production of free radicals, causing oxidative stress. Creatine kinase (CK) is a central controller of energy metabolism in tissues with a large and fluctuating energy demand, and it is highly susceptible to inactivation by free radicals and oxidative damage. Thus, the aim of this study was to evaluate whether a diet for freshwater silver catfish (Rhamdia quelen) containing AFB1 inhibits cerebral CK activity, as well as the involvement of the oxidative stress on this inhibition. Brain CK activity was lower on days 14 and 21 post-feeding in animals that received AFB1-contaminated diet compared to the control group (basal diet), similarly to the brain sodium-potassium pump (Na+, K+-ATPase) activity. On the other hand, lipid peroxidation and protein carbonylation levels were higher on days 14 and 21 post-feeding in animals fed with AFB1-contaminated feed compared to the control group, while the antioxidant capacity against peroxyl radicals and thiol content was lower. Based on these evidences, the data demonstrated that diet containing AFB1 severely affects CK activity, an essential enzyme that plays an important role in brain energy homeostasis. Also, the impairment of energetic homeostasis linked with the use and generation of ATP via inhibition of CK activity elicited an inhibition of enzymes ATP-dependent, such as Na+, K+-ATPase. Moreover, the inhibition of brain CK activity appears to be mediated by the oxidation of lipids, proteins, and thiol group, as well as by a reduction in the antioxidant capacity.

Umbelliferone prevents oxidative stress, inflammation and hematological alterations, and modulates glutamate-nitric oxide-cGMP signaling in hyperammonemic rats.

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication that occurs as a result of liver failure. Umbelliferone (UMB; 7-hydroxycoumarin) is a natural product with proven hepatoprotective activity; however, nothing has yet been reported on its protective effect against hyperammonemia, the main culprit behind the symptoms of HE. Here, we evaluated the effect of UMB against ammonium chloride (NH4Cl)-induced hyperammonemia, oxidative stress, inflammation and hematological alterations in rats. We demonstrated the modulatory role of UMB on the glutamate-nitric oxide (NO)-cGMP pathways in the cerebrum of rats. Rats received intraperitoneal injections of NH4Cl (3 times/week) for 8 weeks and concomitantly received 50 mg/kg UMB. NH4Cl-induced rats showed significantly elevated blood ammonia and liver function markers. Lipid peroxidation and NO were increased in the liver and cerebrum of rats while the antioxidant defenses were declined. UMB significantly reduced blood ammonia, liver function markers, lipid peroxidation and NO, and enhanced the antioxidant defenses in NH4Cl-induced rats. UMB significantly prevented anemia, leukocytosis, thrombocytopenia and prolongation of PT and aPTT. Hyperammonemic rats showed elevated levels of cerebral TNF-α, IL-1ß and glutamine as well as increased activity and expression of Na+/K+-ATPase, effects that were significantly reversed by UMB. In addition, UMB down-regulated nitric oxide synthase and soluble guanylate cyclase in the cerebrum of hyperammonemic rats. In conclusion, this study provides evidence that UMB protects against hyperammonemia via attenuation of oxidative stress and inflammation. UMB prevents hyperammonemia associated hematological alterations and therefore represents a promising protective agent against the deleterious effects of excess ammonia.

The PKA-C3 catalytic subunit is required in two pairs of interneurons for successful mating of Drosophila.

Protein kinase A (PKA) has been shown to play a role in a plethora of cellular processes ranging from development to memory formation. Its activity is mediated by the catalytic subunits whereby many species express several paralogs. Drosophila encodes three catalytic subunits (PKA-C1-3) and whereas PKA-C1 has been well studied, the functions of the other two subunits were unknown. PKA-C3 is the orthologue of mammalian PRKX/Pkare and they are structurally more closely related to each other than to other catalytic subunits within their species. PRKX is expressed in the nervous system in mice but its function is also unknown. We now show that the loss of PKA-C3 in Drosophila causes copulation defects, though the flies are active and show no defects in other courtship behaviours. This phenotype is specifically due to the loss of PKA-C3 because PKA-C1 cannot replace PKA-C3. PKA-C3 is expressed in two pairs of interneurons that send projections to the ventro-lateral protocerebrum and the mushroom bodies and that synapse onto motor neurons in the ventral nerve cord. Rescue experiments show that expression of PKA-C3 in these interneurons is sufficient for copulation, suggesting a role in relaying information from the sensory system to motor neurons to initiate copulation.

Characterization of goose SPMS: Molecular characterization and expression profiling of SPMS in the goose ovary.

Spermine synthase (SPMS), which converts spermidine into spermine, is essential for normal cell growth and development processes in humans and other mammals, but the molecular characterization and expression profiling of the SPMS gene remain undetermined in goose tissues and ovarian follicles. In this study, the SPMS cDNA sequence of the Sichuan white goose was cloned and analysed, and SPMS mRNA expression was profiled in various tissues and ovarian follicles. The results showed that the open reading frame of the SPMS cDNA sequence was 1092 bp in length, encoding 363 amino acids with a molecular weight of 41 kDa. Among all the examined tissues, SPMS expression was highest in the spleen and cerebrum and lowest in the breast and thigh muscles. SPMS expression in the F1 follicle was significantly higher than that in the POF (except for POF2) (P < 0.05). Our results indicate that SPMS might play an important role in follicular development and ovulation.

Effects of Zinc and N-Acetylcysteine in Damage Caused by Lead Exposure in Young Rats.

This study investigated the toxicity of rats exposed to lead acetate (AcPb) during the second phase of brain development (8-12 days postnatal) in hematological and cerebral parameters. Moreover, the preventive effect of zinc chloride (ZnCl2) and N-acetylcysteine (NAC) was investigated. Pups were injected subcutaneously with saline (0.9% NaCl solution), ZnCl2 (27 mg/kg/day), NAC (5 mg/kg/day) or ZnCl2 plus NAC for 5 days (3rd-7th postnatal days), and with saline (0.9% NaCl solution) or AcPb (7 mg/kg/day) in the five subsequent days (8th-12th postnatal days). Animals were sacrificed 21 days after the last AcPb exposure. Pups exposed to AcPb presented inhibition of blood porphobilinogen-synthase (PBG-synthase) activity without changes in hemoglobin content. ZnCl2 pre-exposure partially prevented PBG-synthase inhibition. Regarding neurotoxicity biomarkers, animals exposed to AcPb presented a decrease in cerebrum acetylcholinesterase (AChE) activity and an increase in Pb accumulation in blood and cerebrum. These changes were prevented by pre-treatment with ZnCl2, NAC, and ZnCl2 plus NAC. AcPb exposure caused no alteration in behavioral tasks. In short, results show that AcPb inhibited the activity of two important enzymatic biomarkers up to 21 days after the end of the exposure. Moreover, ZnCl2 and NAC prevented the alterations induced by AcPb.

Galactose alters markers of oxidative stress and acetylcholinesterase activity in the cerebrum of rats: protective role of antioxidants.

We evaluated the in vitro effects of galactose at 0.1, 3.0, 5.0 and 10.0 mM on thiobarbituric acid-reactive substances (TBA-RS), total sulfhydryl content, protein carbonyl content, on the activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and on acetylcholinesterase (AChE) activity in the cerebral cortex, cerebellum and hippocampus of rats. We also investigated the influence of the antioxidants (each at 1 mM), α-tocopherol, ascorbic acid and glutathione, on the effects elicited by galactose on the parameters tested. Results showed that galactose, at a concentration of 3.0 mM, enhanced TBA-RS levels in the hippocampus, cerebral cortex and cerebellum of rats. In the cerebral cortex, galactose at concentrations of 5.0 and 10.0 mM increased TBA-RS and protein carbonyl content, and at 10.0 mM increased CAT activity and decreased AChE activity. In the cerebellum, galactose at concentrations of 5.0 and 10.0 mM increased TBA-RS, SOD and GSH-Px activities. In the hippocampus, galactose at concentrations of 5.0 and 10.0 mM increased TBA-RS and CAT activity and at 10.0 mM decreased GSH-Px. Data showed that at the pathologically high concentration (greater than 5.0 mM), galactose induces lipid peroxidation, protein carbonylation, alters antioxidant defenses in the cerebrum, and also alters cholinesterase activity. Trolox, ascorbic acid and glutathione addition prevented the majority of alterations in oxidative stress parameters and the decrease in AChE activity that were caused by galactose. Our findings lend support to a potential therapeutic strategy for this condition, which may include the use of appropriate antioxidants for ameliorating the damage caused by galactose.

Penconazole alters redox status, cholinergic function, and membrane-bound ATPases in the cerebrum and cerebellum of adult rats.

Pesticides exposure causes usually harmful effects to the environment and human health. The present study aimed to investigate the potential toxic effects of penconazole, a triazole fungicide, on the cerebrum and cerebellum of adult rats. Penconazole was administered intraperitoneally to male Wistar rats at a dose of 67 mg kg-1 body weight every 2 days during 9 days. Results showed that penconazole induced oxidative stress in rat cerebrum and cerebellum tissues. In fact, we have found a significant increase in malondialdehyde, hydrogen peroxide, and advanced oxidation protein product levels, as well as an alteration of the antioxidant status, enzymatic (superoxide dismutase and catalase) and nonenzymatic (glutathione), the cholinergic function, and membrane-bound ATPases (Na+/K+-ATPase and Mg2+-ATPase). Penconazole also provoked histological alterations marked by pyknotic and vacuolated neurons in the cerebrum and apoptosis and edema in the cerebellum Purkinje cells' layer. Therefore, the use of this neurotoxicant fungicide must be regularly monitored in the environment.

Topological and histological description of preoptic area and hypothalamus in cardinal tetra Paracheirodon axelrodi (Characiformes: Characidae)

Topological and histological descriptions of the preoptic area and hypothalamus of the cardinal tetra Paracheirodon axelrodi were performed. Standard histological paraffin sections were used and stained with Nissl technique, and plastic sections for high-resolution optic microscopy (HROM). The preoptic area showed some differences related to the location of the magnocellular preoptic nucleus (PM) and the size of the neurons in this region, as they were the biggest in all the preoptic area. Additionally, within the preoptic area, the different structures that comprise the organum vasculosum of the lamina terminalis (OVLT) were identified and characterized. The hypothalamus could be subdivided in three regions - the ventral, the dorsal and the caudal hypothalamic regions - neuron morphology, size and staining pattern were similar in all of them.(AU)

ESUMEN Se realizó la descripción topológica e histológica del área preóptica e hipotálamo en el Neón cardenal Paracheirodon axelrodi. Se usaron cortes obtenidos con tecnicas histológicas estándar, coloreados con técnica de Nissl y secciones en resina con microscopía óptica de alta resolución (MOAR). El área preóptica muestra algunas diferencias relacionadas con la localización del núcleo preóptico magnocelular (PM) y el tamaño de algunas neuronas en esta región, puesto que estas eran las más grandes de toda el área preoptica. Adicionalmente, dentro del área preóptica, fue posible identificar y caracterizar las diferentes estructuras que componen el órgano vasculoso de la lámina media (OVLM). El hipotálamo puede sudividirse en tres zonas: la zona hipotalámica ventral, la zona hipotalámica dorsal y la zona hipotalámica caudal. La morfología de las neuronas de los núcleos que comprenden las diferentes zonas del hipotálamo tiene tamaño, forma y coloración similar.(AU)

Transformation of catalytic characteristics of cerebral monoamine oxidases in experimental posttraumatic stress disorders.

We studied the contribution of the transformation of the catalytic properties of cerebral monoamine oxidase in the development of behavioral disorders during stress. Monoamine oxidase activities and catalytic characteristics, LPO intensity, and oxidative modification of proteins in suspension of the brain mitochondria were evaluated over the course of experimental posttraumatic stress disorder. The detected shifts were comparable with the results of neuroethologic testing. The development of behavioral disorders presented by low exploratory activity and high anxiety was associated with transformation of catalytic characteristics of cerebral monoamine oxidases, associated with the development of oxidative stress with predominant intensification of metal-catalyzed protein oxidation.

Aspartame Administration and Insulin Treatment Altered Brain Levels of CYP2E1 and CYP3A2 in Streptozotocin-Induced Diabetic Rats.

This study demonstrates that aspartame consumption and insulin treatment in a juvenile diabetic rat model leads to increase in cytochrome P450 (CYP) 2E1 and CYP3A2 isozymes in brain. Diabetes mellitus was induced in postweaned 21-day-old Wistar male rat by streptozotocin. Animals were randomly assigned to one of the following groups: untreated control, diabetic (D), D-insulin, D-aspartame, or the D-insulin + aspartame-treated group. Brain and liver tissue samples were used to analyze the activity of CYP2E1 and CYP3A2 and protein levels. Our results indicate that combined treatment with insulin and aspartame in juvenile diabetic rats significantly induced CYP2E1 in the cerebrum and cerebellum without modifying it in the liver, while CYP3A2 protein activity increased both in the brain and in the liver. The induction of CYP2E1 in the brain could have important in situ toxicological effects, given that this CYP isoform is capable of bioactivating various toxic substances. Additionally, CYP3A2 induction in the liver and brain could be considered a decisive factor in the variation of drug response and toxicity.

Preventive effect of CuCl2 on behavioral alterations and mercury accumulation in central nervous system induced by HgCl2 in newborn rats.

This study investigated the benefits of Cu preexposition on Hg effects on behavioral tests, acetylcholinesterase (AChE) activity and Hg, and essential metal contents in the cerebrum and cerebellum of neonate rats. Wistar rats received (subcutaneous) saline or CuCl2 ·2H2O (6.9 mg/kg/day) when they were 3 to 7 days old and saline or HgCl2 (5.0 mg/kg/day) when they were 8 to 12 days old. Mercury exposure reduced the performance of rats in the negative geotaxis (3-13 days) and beaker test (17-20 days), inhibited cerebellum AChE activity (13 days), increased cerebrum and cerebellum Hg (13 days), cerebrum Cu (13 days), and cerebrum and cerebellum Zn levels (33 days). The performance of rats in the tail immersion and rotarod tests as well as Fe and Mg levels were not altered by treatments. Copper prevented all alterations induced by mercury. These results are important to open a new perspective of prevention and/or therapy for mercury exposure.

Effect of swainsonine in Oxytropis kansuensis on Golgi α-mannosidase II expression in the brain tissues of Sprague-Dawley rats.

The purpose of this study was to observe the effects of swainsonine in Oxytropis kansuensis on the expression of Golgi α-mannosidase II (MAN2A1) in the brain tissues of Sprague-Dawley (SD) rats. Twenty-four SD rats were randomly divided into four groups (experimental groups I, II, and III and a control group) of six animals each. The rats were penned as groups and fed feeds containing either 15% (swainsonine content = 0.003%), 30% (swainsonine content = 0.006%), or 45% (swainsonine content = 0.009%) O. kansuensis for experimental groups I-III, respectively, or complete feed for the control group. One hundred and nineteen days after poisoning, all rats showed neurological disorders at different degrees, which were considered to be successful establishment of a chronic poisoning model of O. kansuensis. Rats were sacrificed, and MAN2A1 expression of brain tissues was detected by immunohistochemistry and RT-PCR. The results showed that MAN2A1 was either not expressed or lowly expressed in the molecular layer of the cerebral cortex and hippocampal layers, but was found to be highly expressed in other areas of the brain. MAN2A1 expression decreased in the cerebrum and cerebellum in experimental groups when compared to the control group, whereas the expression of MAN2A1 mRNA was inhibited in cerebral and cerebellar tissues by O. kansuensis. These results indicated that O. kansuensis treatment could reduce the expression of MAN2A1 in brain tissues of SD rats.

Role of nitric oxide synthases in early blood-brain barrier disruption following transient focal cerebral ischemia.

The role of nitric oxide synthases (NOSs) in early blood-brain barrier (BBB) disruption was determined using a new mouse model of transient focal cerebral ischemia. Ischemia was induced by ligating the middle cerebral artery (MCA) at its M2 segment and reperfusion was induced by releasing the ligation. The diameter alteration of the MCA, arterial anastomoses and collateral arteries were imaged and measured in real time. BBB disruption was assessed by Evans Blue (EB) and sodium fluorescein (Na-F) extravasation at 3 hours of reperfusion. The reperfusion produced an extensive vasodilation and a sustained hyperemia. Although expression of NOSs was not altered at 3 hours of reperfusion, L-NAME (a non-specific NOS inhibitor) abolished reperfusion-induced vasodilation/hyperemia and significantly reduced EB and Na-F extravasation. L-NIO (an endothelial NOS (eNOS) inhibitor) significantly attenuated cerebral vasodilation but not BBB disruption, whereas L-NPA and 7-NI (neuronal NOS (nNOS) inhibitors) significantly reduced BBB disruption but not cerebral vasodilation. In contrast, aminoguanidine (AG) (an inducible NOS (iNOS) inhibitor) had less effect on either cerebral vasodilation or BBB disruption. On the other hand, papaverine (PV) not only increased the vasodilation/hyperemia but also significantly reduced BBB disruption. Combined treatment with L-NAME and PV preserved the vasodilation/hyperemia and significantly reduced BBB disruption. Our findings suggest that nNOS may play a major role in early BBB disruption following transient focal cerebral ischemia via a hyperemia-independent mechanism.

An investigation of the effect of thiamine pyrophosphate on cisplatin-induced oxidative stress and DNA damage in rat brain tissue compared with thiamine: thiamine and thiamine pyrophosphate effects on cisplatin neurotoxicity.

This study investigated the effects of thiamine pyrophosphate (TPP) at dosages of 10 and 20 mg/kg on oxidative stress induced in rat brain tissue with cisplatin and compared this with thiamine. Cisplatin neurotoxicity represents one of the main restrictions on the drug being given in effective doses. Oxidative stress is considered responsible for cisplatin toxicity. Our results showed that cisplatin increased the levels of oxidant parameters such as lipid peroxidation (thio barbituric acid reactive substance (TBARS)) and myeloperoxidase (MPO) in brain tissue and suppressed the effects of antioxidants such as total glutathione (GSH) and superoxide dismutase (SOD). TPP, especially at a dosage of 20 mg/kg, significantly reduced TBARS and MPO levels that increase with cisplatin administration compared with the thiamine group, while TPP significantly increases GSH and SOD levels. In addition, the level of 8-Gua (guanine), a product of DNA damage, was 1.7 ± 0.12 8-hydroxyl guanine (8-OH Gua)/105 Gua in brain tissue in the control group receiving cisplatin, compared with 0.97 ± 0.03 8-OH Gua/105 Gua in the thiamine pyrophosphate (20 mg/kg) group and 1.55 ± 0.11 8-OH Gua/105 Gua in the thiamine (20 mg/kg) group. These results show that thiamine pyrophosphate significantly prevents oxidative damage induced by cisplatin in brain tissue, while the protective effect of thiamine is insignificant.

Resveratrol increases cerebral glycogen synthase kinase phosphorylation as well as protein levels of drebrin and transthyretin in mice: an exploratory study.

Alzheimer's disease (AD) is characterized by intraneuronal ß-amyloid plaques and hyperphosphorylated tau, leading to neuronal cell death and progressive memory losses. This exploratory work investigates if dietary resveratrol, previously shown to have broad anti-aging effects and improve AD pathology in vivo, leads to neuroprotective changes in specific protein targets in the mouse brain. Both wild-type and APP/PS1 mice, a transgenic AD mouse model, received control AIN-93G diet or AIN-93G supplemented with resveratrol. Pathology parameters and AD risk were assessed via measurements on plaque burden, levels of phosphorylated glycogen synthase kinase 3-ß (GSK3-ß), tau, transthyretin and drebrin. Dietary resveratrol treatment did not decrease plaque burden in APP/PS1 mice. However, resveratrol-fed mice demonstrated increases in GSK3-ß phosphorylation, a 3.8-fold increase in protein levels of transthyretin, and a 2.2-fold increase in drebrin. This study broadens our understanding of specific mechanisms and targets whereby resveratrol provides neuroprotection.

Late-onset dietary restriction modulates protein carbonylation and catalase in cerebral hemispheres of aged mice.

Oxidative stress is an important factor in causing aging and age-related diseases. It is caused by an imbalance between oxidants such as reactive oxygen species (ROS) and antioxidants. Protein oxidation elicited by free radicals may cause protein function disruptions. Protein carbonylation, an irreversible process resulting in loss of function of the modified proteins, is a widely used marker for oxidative stress. In the present study, we have evaluated the levels of protein carbonyls, ROS, and catalase in the cerebral hemispheres of young and aged mice. When aged mice were subjected to a dietary restriction (DR) regimen (alternate days feeding) of 3 months, a significant reduction in the endogenous levels of protein carbonylation as well as ROS and elevation of catalase was observed in their cerebral hemispheres. The present study, thus, demonstrated the antioxidative effects of late-onset DR regimen in the cerebral hemispheres of aged mice which may act as a powerful modulator of age-related neurodegenerative diseases.

In vitro glutathione peroxidase mimicry of ebselen is linked to its oxidation of critical thiols on key cerebral suphydryl proteins - A novel component of its GPx-mimic antioxidant mechanism emerging from its thiol-modulated toxicology and pharmacology.

The antioxidant mechanism of ebselen in rats brain is largely linked with its glutathione peroxidase (GPx) rather than its peroxiredoxin mimicry ability. However, the precise molecular dynamics between the GPx-mimicry of ebselen and thiol utilization is yet to be fully clarified and thus still open. Herein, we investigated the influence of dithiothreitol (DTT) on the antioxidant action of ebselen against oxidant-induced cerebral lipid peroxidation and deoxyribose degradation. Furthermore, the critical inhibitory concentrations of ebselen on the activities of sulphydryl enzymes such as cerebral sodium pump, δ-aminolevulinic acid dehydratase (δ-ALAD) and lactate dehydrogenase (LDH) were also investigated. We observe that ebselen (at ≥42 µM) markedly inhibited lipid peroxidation in the presence and absence of DTT, whereas it inhibited deoxyribose degradation only in the presence of DTT. Furthermore, under in vitro conditions, ebselen inhibited the thiol containing enzymes; cerebral sodium pump (at ≥40 µM), δ-ALAD (≥10 µM) and LDH (≥1 µM) which were either prevented or reversed by DTT. However, the inhibition of the activities of these sulphydryl proteins in diabetic animals was prevented by ebselen. Summarily, it is apparent that the effective in vitro inhibitory doses of ebselen on the activity of the sulphydryl proteins are far less than its antioxidant doses. In addition, the presence of DTT is evidently a critical requirement for ebselen to effect its antioxidant action against deoxyribose degeradation and not lipid peroxidation. Consequently, we conclude that ebselen possibly utilizes available thiols on sulphydryl proteins to effect its GPx mimicry antioxidant action against lipid peroxidation in rat brain homogenate.

Dependence on NIRS source-detector spacing of cytochrome c oxidase response to hypoxia and hypercapnia in the adult brain.

Transcranial near-infrared spectroscopy (NIRS) provides an assessment of cerebral oxygen metabolism by monitoring concentration changes in oxidised cytochrome c oxidase Δ[oxCCO]. We investigated the response of Δ[oxCCO] to global changes in cerebral oxygen delivery at different source-detector separations in 16 healthy adults. Hypoxaemia was induced by delivery of a hypoxic inspired gas mix and hypercapnia by addition of 6 % CO2 to the inspired gases. A hybrid optical spectrometer was used to measure frontal cortex light absorption and scattering at discrete wavelengths and broadband light attenuation at 20, 25, 30 and 35 mm. Without optical scattering changes, a decrease in cerebral oxygen delivery, resulting from the reduction in arterial oxygen saturation during hypoxia, led to a decrease in Δ[oxCCO]. In contrast, Δ[oxCCO] increased when cerebral oxygen delivery increased due to increased cerebral blood flow during hypercapnia. In both cases the magnitude of the Δ[oxCCO] response increased from the detectors proximal (measuring superficial tissue layers) to the detectors distal (measuring deep tissue layers) to the broadband light source. We conclude that the Δ[oxCCO] response to hypoxia and hypercapnia appears to be dependent on penetration depth, possibly reflecting differences between the intra- and extracerebral tissue concentration of cytochrome c oxidase.