Nitric oxide and nitric oxide synthases in the fetal cerebral cortex of rats following transient uteroplacental ischemia

Prophylactic zinc and therapeutic selenium administration in adult rats prevents long-term cognitive and behavioral sequelae by a transient ischemic attack

The transient hypoxic-ischemic attack, also known as a minor stroke, can result in long-term neurological issues such as memory loss, depression, and anxiety due to an increase in nitrosative stress. The individual or combined administration of chronic prophylactic zinc and therapeutic selenium is known to reduce nitrosative stress in the first seven days post-reperfusion and, due to an antioxidant effect, prevent cell death. Besides, zinc or selenium, individually administered, also causes antidepressant and anxiolytic effects. Therefore, this work evaluated whether combining zinc and selenium could prevent stroke-elicited cognition and behavior deficits after 30 days post-reperfusion. Accordingly, we assessed the expression of growth factors at 7 days post-reperfusion, a four-time course of memory (from 7 to 28 days post-learning test), and cell proliferation, depression, and anxiety-like behavior at 30 days post-reperfusion. Male Wistar rats with a weight between 190 and 240 g) were treated with chronic prophylactic zinc administration with a concentration of 0.2 mg/kg for 15 days before common carotid artery occlusion (10 min) and then with therapeutic selenium (6 μg/kg) for 7 days post-reperfusion. Compared with individual administrations, the administration combined of prophylactic zinc and therapeutic selenium decreased astrogliosis, increased growth factor expression, and improved cell proliferation and survival in two regions, the hippocampus, and cerebral cortex. These effects prevented memory loss, depression, and anxiety-like behaviors. In conclusion, these results demonstrate that the prophylactic zinc administration combined with therapeutic selenium can reduce the long-term sequelae caused by the transient ischemic attack. Significance statement. A minor stroke caused by a transient ischemic attack can result in psychomotor sequelae that affect not only the living conditions of patients and their families but also the economy. The incidence of these micro-events among young people has increased in the world. Nonetheless, there is no deep understanding of how this population group responds to regular treatments (Ekker and et al., 2018) [1]. On the basis that zinc and selenium have antioxidant, anti-inflammatory, and regenerative properties in stroke animal models, our work explored whether the chronic combined administration of prophylactic zinc and therapeutic selenium could prevent neurological sequelae in the long term in a stroke rat model of unilateral common carotid artery occlusion (CCAO) by 10-min. Our results showed that this combined treatment provided a long-term neuroprotective effect by decreasing astrogliosis, memory loss, anxiety, and depression-like behavior.

Exploring the chondroitin sulfate nanogel's potential in combating nephrotoxicity induced by cisplatin and doxorubicin-An in-vivo study on rats

In this study, we aim to unveil the potential of itaconyl chondroitin sulfate nanogel (ICSNG) in tackling chronic kidney diseases triggered by the administration of CDDP and doxorubicin (Adriamycin, ADR). To that end, the new drug delivery system (ICSNG) was initially prepared, characterized, and loaded with the target drugs. Thereafter, the in-vivo studies were performed using five equally divided groups of 100 male Sprague-Dawley (SD) rats. Biochemical evaluation and immunohistochemistry studies have revealed the renal toxicity and the ameliorative effects of ICSNG on renal function. When ICSNG-based treatments were contrasted with the CDDP and ADR infected groups, they significantly increased paraoxonase-1 (PON-1), superoxide dismutase (SOD), catalase (CAT) and albumin activity and significantly decreased nitric oxide (NO), tumor necrosis factor alpha (TNF-α), creatinine, urea, and cyclooxygenase-2 (COX-2) activity (p < 0.001). The findings of the current study imply that ICSNG may be able to lessen renal inflammation and damage in chronic kidney disorders brought on by the administration of CDDP and ADR. Interestingly, according to the estimated selectivity indices, the ICSNG-encapsulated drugs have demonstrated superior selectivity for cancer MCF-7 cells, over healthy HSF cells, in comparison to the bare drugs.

The diminution and modulation role of water-soluble gallic acid-carboxymethyl chitosan conjugates against the induced nephrotoxicity with cisplatin

The toxicity of cisplatin (CDDP) toward the renal tubules and its severe effects on the proximal tubules limits its further use in cancer therapy. The current study was undertaken to evaluate the protective effects of gallic acid-grafted O-carboxymethyl chitosan (GA@CMCS) against nephrotoxicity induced by CDDP in rats. Renal injury was assessed in the GA@CMCS/CDDP-treated rats using kidney injury molecule-1 (KIM-1). Moreover, the levels of reduced glutathione (GSH), malondialdehyde (MDA), and nitric oxide (NO) were measured. The comet assay was performed to measure the DNA damage. The renoprotective activity of GA@CMCS was supported by histo- and immuno-pathological studies of the kidney. GA@CMCS significantly normalized the increases in kidney homogenate of KIM-1, MDA, and NO-induced by CDDP and significantly increased GSH as compared with the CDDP group. GA@CMCS also significantly protects rat kidneys from CDDP-induced histo- and immuno-pathological changes. Both biochemical findings and histo- and immuno-pathological evidence showed the renoprotective potential of GA@CMCS against CDDP-induced oxidative stress, inflammation, and renal dysfunction in rats. In conclusion, GA@CMCS has been shown to mitigate the nephrotoxicity impact of CDDP in cancer therapy.

Hypothermic preconditioning attenuates hypobaric hypoxia induced spatial memory impairment in rats

Hypobaric Hypoxia (HH) is known to cause oxidative stress in the brain that leads to spatial memory deficit and neurodegeneration. For decades therapeutic hypothermia is used to treat global and focal ischemia in preserving brain functions that proved to be beneficial in humans and rodents. Considering these previous reports, the present study was designed to establish the therapeutic potential of hypothermia preconditioning on HH induced spatial memory, biochemical and morphological changes in adult rats. Male Sprague Dawley rats were exposed to HH (7620 m, ~ 282 mmHg) for 1, 3 and 7 days with and without hypothermic preconditioning. Spatial learning memory was assessed by Morris water maze (MWM) test along with evaluation of hippocampal pyramidal neuron damage by histological study. Oxidative stress was measured by studying the levels of nitric oxide (NO), reactive oxygen species (ROS), lipid peroxidation (LPO), oxidized and reduced glutathione (GSSG and GSH). Results of MWM test indicated prolonged path length and latency to reach the platform in HH groups that regained to normal in cold pre-treated groups. A likely neurodegeneration was evident in HH groups that lessen in the cold pre-treated groups. Hypothermic preconditioning prevented spatial memory impairment and neurodegeneration in animals subjected to HH via decreasing the NO, ROS and LPO compared to control animals. The GSH level and GSH/GSSG ratio was found to be higher in preconditioned animals as compared to respective HH exposed animals, indicative of redox scavenging and restoration of hippocampal neuronal structure as well as spatial memory. Therefore, hypothermic preconditioning improves spatial memory deficit by reducing HH induced oxidative stress and hippocampal neurodegeneration, hence can be used as a multi-target prophylactic measure to combat HH induced neurodegeneration.

Long-term taurine administration improves motor skills in a tubulinopathy rat model by decreasing oxidative stress and promoting myelination

The taiep rat undergoes hypomyelination and progressive demyelination caused by an abnormal microtubule accumulation in oligodendrocytes, which elicits neuroinflammation and motor behavior dysfunction. Based on taurine antioxidant and proliferative actions, this work explored whether its sustained administration from the embryonic age to adulthood could prevent neuroinflammation, stimulate cell proliferation, promote myelination, and relieve motor impairment. Taurine (50 mg/L of drinking water = 50 ppm) was given to taiep pregnant rats on gestational day 15 and afterward to the male offspring until eight months of age. We measured the levels of nitric oxide (NO), malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA), CXCL1, CXCR2 receptor, growth factors (BNDF and FGF2), cell proliferation, and myelin content over time. Integral motor behavior was also evaluated. Our results showed that taurine administration significantly decreased NO and MDA + 4-HDA levels, increased cell proliferation, and promoted myelination in an age- and brain region-dependent fashion compared with untreated taiep rats. Taurine effect on chemokines and growth factors was also variable. Taurine improved vestibular reflexes and limb muscular strength in perinatal rats and fine movements and immobility episodes in adult rats. These results show that chronic taurine administration partially alleviates the taiep neuropathology.

Taurine Increases Zinc Preconditioning-Induced Prevention of Nitrosative Stress, Metabolic Alterations, and Motor Deficits in Young Rats following Intrauterine Ischemia

Oxygen deprivation in newborns leads to hypoxic-ischemic encephalopathy, whose hallmarks are oxidative/nitrosative stress, energetic metabolism alterations, nutrient deficiency, and motor behavior disability. Zinc and taurine are known to protect against hypoxic-ischemic brain damage in adults and neonates. However, the combined effect of prophylactic zinc administration and therapeutic taurine treatment on intrauterine ischemia- (IUI-) induced cerebral damage remains unknown. The present work evaluated this issue in male pups subjected to transient IUI (10 min) at E17 and whose mothers received zinc from E1 to E16 and taurine from E17 to postnatal day 15 (PND15) via drinking water. We assessed motor alterations, nitrosative stress, lipid peroxidation, and the antioxidant system comprised of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Enzymes of neuronal energetic pathways, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH), were also evaluated. The hierarchization score of the protective effect of pharmacological strategies (HSPEPS) was used to select the most effective treatment. Compared with the IUI group, zinc, alone or combined with taurine, improved motor behavior and reduced nitrosative stress by increasing SOD, CAT, and GPx activities and decreasing the GSSG/GSH ratio in the cerebral cortex and hippocampus. Taurine alone increased the AST/ALT, LDH/ALT, and AST/LDH ratios in the cerebral cortex, showing improvement of the neural bioenergetics system. This result suggests that taurine improves pyruvate, lactate, and glutamate metabolism, thus decreasing IUI-caused cerebral damage and relieving motor behavior impairment. Our results showed that taurine alone or in combination with zinc provides neuroprotection in the IUI rat model.

Redox modification of ryanodine receptor contributes to impaired Ca2+ homeostasis and exacerbates muscle atrophy under high altitude

At extreme altitude, prolonged and severe hypoxia menaces human function and survival, and also associated with profound loss of muscle mass which results into a debilitating critical illness of skeletal muscle atrophy. Hypobaric hypoxia altered redox homeostasis and impaired calcium ion handling in skeletal muscles. Dysregulated Ca²⁺ homeostasis and activated calpain is the prime stressor in high altitude hypoxia while the reason for subsequent abnormal release of pathological Ca²⁺ into cytoplasm is largely unexplored. The present study identified the redox remodeling in the Ca²⁺ release channel, Ryanodine Receptor (RyR1) owing to its hypernitrosylation state in skeletal muscles in chronic hypobaric hypoxia exposed rats. RyR1-hypernitrosylation decreases the binding of FKBP12/calstabin-1 and other complexes from the channel, causing "leakiness" in RyR1 ion-channel. A strong RyR1 stabilizer, S107 enhanced binding affinity of FKBP12 with hypernitrosylated RyR1, reduced Sarco(endo)plasmic reticulum (SR) Ca²⁺ leak and improved muscle strength and function under chronic hypoxia. Administration of S107 inhibited the skeletal muscle damage, maintained ultrastructure of sarcomere and sarcolemmal integrity. Histological analysis proved the increase in cross-sectional area of myofibers. Further, the number of apoptotic cells was also reduced by S107 treatment. Conclusively, we proposed that the redox remodeling of RyR1 (hypernitrosylated-RyR1) might be responsible for dysregulated Ca²⁺ homeostasis which consequently impaired muscle strength and function in response to chronic hypoxic stress. Reduced SR Ca²⁺ leak and enhanced binding affinity of FKBP12 may provide a novel therapeutic avenue in ameliorating skeletal muscle atrophy at high altitude.

Cellular mechanisms underlying the rapid depolarization caused by oxygen and glucose deprivation in layer III pyramidal cells of the somatosensory cortex

Cortical pyramidal neurons show rapid and irreversible membrane depolarization in response to oxygen-glucose depolarization (OGD). In this study, we investigated cellular mechanisms responsible for rapid depolarization caused by OGD in layer III pyramidal neurons of the mouse somatosensory cortex. When OGD solution was perfused in the presence of Ca²⁺ chelator and inhibitors of ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate receptors (IP₃Rs) in the pipette solution or in the presence of inhibitors of NMDA receptors (NMDARs), voltage-gated Ca²⁺ channels (VGCCs), and canonical transient receptor potential (TRPC) channels in the perfusion solution, the latency of the rapid depolarization was significantly prolonged compared to the control. In addition, when OGD solution was perfused in the presence of scavengers of nitric oxide and reactive oxygen species in the perfusion solution or in the presence of calcineurin inhibitors in the pipette solution, the latency of the rapid depolarization was significantly prolonged compared to the control. These data indicate that OGD-induced intracellular Ca²⁺ increases mediated by Ca²⁺ influx through NMDARs, VGCCs and TRPC channels as well as by Ca²⁺ release from RyRs and IP₃Rs lead to mitochondrial impairment, which may facilitate the generation of the rapid depolarization via dysfunction of Na⁺-K⁺-ATPase due to decreased ATP production.

Role of 904 nm superpulsed laser-mediated photobiomodulation on nitroxidative stress and redox homeostasis in burn wound healing

BACKGROUND

Burn wound healing is delayed due to several critical factors such as sustained inflammation, vascular disorder, neuropathy, enhanced proteolysis, infection, and oxidative stress. Burn wounds have limited oxygen supply owing to compromised blood circulation. Hypoxic burn milieu leads to free radicals overproduction incurring oxidative injury, which impedes repair process causing damage to cell membranes, proteins, lipids, and DNA. Photobiomodulation (PBM) with 904 nm superpulsed laser had shown potent healing efficacy via attenuating inflammation while enhancing proliferation, angiogenesis, collagen accumulation, and bioenergetic activation in burn wounds.

METHODS

This study investigated the effects of 904 nm superpulsed laser at 0.4 mW/cm² average power density, 0.2 J/cm² total energy density, 100 Hz frequency, and 200 ns pulse width for 10 min daily for seven days postburn injury on nitroxidative stress, endogenous antioxidants status, and redox homeostasis.

RESULTS

Photobiomodulation treatment significantly decreased reactive oxygen species, nitric oxide, and lipid peroxidation levels as compared to non-irradiated control. Further, protective action of PBM against protein oxidative damage was evidenced by reduced protein carbonylation and advanced oxidation protein product levels along with significantly enhanced endogenous antioxidants levels of SOD, catalase, GPx, GST, reduced glutathione, and thiol (T-SH, Np-SH, P-SH). Biochemical changes aid in reduction of oxidative stress and maintenance of redox homeostasis, which further well corroborated by significantly up-regulated protein expression of Nrf 2, hemeoxygenase (HO-1), and thioredoxin reductase 2 (Txnrd2).

CONCLUSION

Photobiomodulation with 904 nm superpulsed laser led to reduction of nitroxidative stress, induction of endogenous antioxidants, and maintenance of redox homeostasis that could play a vital role in augmentation of burn wound healing.

Prophylactic Zinc and Therapeutic Selenium Administration Increases the Antioxidant Enzyme Activity in the Rat Temporoparietal Cortex and Improves Memory after a Transient Hypoxia-Ischemia

In the cerebral hypoxia-ischemia rat model, the prophylactic administration of zinc can cause either cytotoxicity or preconditioning effect, whereas the therapeutic administration of selenium decreases the ischemic damage. Herein, we aimed to explore whether supplementation of low doses of prophylactic zinc and therapeutic selenium could protect from a transient hypoxic-ischemic event. We administrated zinc (0.2 mg/kg of body weight; ip) daily for 14 days before a 10 min common carotid artery occlusion (CCAO). After CCAO, we administrated sodium selenite (6 μg/kg of body weight; ip) daily for 7 days. In the temporoparietal cerebral cortex, we determined nitrites by the Griess method and lipid peroxidation by the Gerard-Monnier assay. qPCR was used to measure mRNA of nitric oxide synthases, antioxidant enzymes, chemokines, and their receptors. We measured the enzymatic activity of SOD and GPx and protein levels of chemokines and their receptors by ELISA. We evaluated long-term memory using the Morris-Water maze test. Our results showed that prophylactic administration of zinc caused a preconditioning effect, decreasing nitrosative/oxidative stress and increasing GPx and SOD expression and activity, as well as eNOS expression. The therapeutic administration of selenium maintained this preconditioning effect up to the late phase of hypoxia-ischemia. Ccl2, Ccr2, Cxcl12, and Cxcr4 were upregulated, and long-term memory was improved. Pyknotic cells were decreased suggesting prevention of neuronal cell death. Our results show that the prophylactic zinc and therapeutic selenium administration induces effective neuroprotection in the early and late phases after CCAO.

Association Between rs3833912/rs16944 SNPs and Risk for Cerebral Palsy in Mexican Children

Perinatal asphyxia in the neonatal brain triggers a robust inflammatory response in which nitric oxide (NO) generation plays a hazardous role. Increased levels of NO can be maintained by the activity of inducible NO synthase (NOS2A) on its own or activated by IL-1beta (IL-1β) gene transcription and positive back stimulation of the NOS2 (CCTTT)n microsatellite by IL-1β, thus potentiating brain injury after ischemic perinatal asphyxia. We investigated whether the risk for cerebral palsy (CP) increases when an expansion of the − 2.5 kb (CCTTT)n microsatellite in the NOS2A gene and a single nucleotide polymorphism (SNP) in -C511T of the IL- IL-1β gene promoter occur in patients after perinatal hypoxic-ischemic encephalopathy. Genomic DNA was purified from peripheral leukocytes of 48 patients with CP and of 57 healthy control children. IL-1β SNP genotypes were established using a real-time PCR technique and fluorogenic probes and were validated by restriction fragment length polymorphism (RFLP) analysis using the AvaI restriction enzyme. The length of the CCTTTn microsatellite in the NOS2 gene promoter was determined by automated sequencing. The 14 repeat-long allele of the CCTTTn NOS2A microsatellite was present in 27% of CP patients vs 12.3% of controls, showing an odds ratio (OR) = 2.6531 and 95% confidence interval (CI) = 0.9612–7.3232 (P < 0.0469). The -511 TT genotype frequency showed an OR = 2.6325 (95% CI = 1.1348–6.1066, P = 0.0189). Interestingly, the haplotype CCTTT₁₄/TT showed an OR = 9.561 (95%, CI = 1.1321–80.753; P = 0.0164). The haplotype (CCTTT)₁₄/TT, formed by the expansion of the − 2.5 kb (CCTTT)_n microsatellite in the NOS2A gene promoter and the -511 C➝ T SNP of the IL-1β gene promoter, might be a useful marker to identify patients who are at high risk for developing CP after hypoxic-ischemic encephalopathy.

The MAPK-activator protein-1 signaling regulates changes in lung tissue of rat exposed to hypobaric hypoxia

This study reports the role of MAPKs (JNK, ERK, and p38), and activator protein-1 (AP-1) transcription factor in the hypobaric hypoxia induced change in lung tissue. Healthy male Sprague-Dawley rats were exposed to hypobaric hypoxia for 6, 12, 24, 48, 72, and 120 hr. Hypoxia resulted in significant increase in reactive oxygen species (ROS), vascular endothelial growth factor (VEGF) and decreased nitric oxide (NO), these act as signaling molecules for activation of MAPK and also contribute in development of vascular leakage (an indicator of pulmonary edema) as confirmed by histological studies. Our results confirmed JNK activation as an immediate early response (peaked at 6-48 hr), activation of ERKs (peaked at 24-72 hr) and p38 (peaked at 72-120 hr) as a secondary response to hypoxia. The MAPK pathway up regulated its downstream targets phospho c-Jun (peaked at 6-120 hr), JunB (peaked at 24-120 hr) however, decreased c-Fos, and JunD levels. DNA binding activity also confirmed activation of AP-1 transcription factor in lung tissue under hypobaric hypoxia. Further, we analyzed the proliferative and inflammatory genes regulated by different subunits of AP-1 to explore its role in vascular leakage. Increased expression of cyclin D1 (peaked at 12-72 hr) and p16 level (peaked at 48-120 hr) were correlated to the activation of c-jun, c-Fos and JunB. Administration of NFκB inhibitor caffeic acid phenethyl ester (CAPE) and SP600125 (JNK inhibitor) had no effect on increased levels of Interferon-γ (IFN-γ), Interleukin-1 (IL-1), and Tumor Necrosis Factor-α (TNF-α) thereby confirming the involvement of AP-1 as well as NFκB in inflammation. Expression of c-jun, c-Fos were correlated with activation of proliferative genes and JunB, Fra-1 with pro-inflammatory cytokines. In conclusion immediate response to hypobaric hypoxia induced c-Jun:c-Fos subunits of AP-1; responsible for proliferation that might cause inhomogeneous vasoconstriction leading to vascular leakage and inflammation at increased duration of hypobaric hypoxia exposure.

N-stearoyltyrosine protects primary cortical neurons against oxygen-glucose deprivation-induced apoptosis through inhibiting anandamide inactivation system

N-stearoylthrosine (NST), a synthesized anandamide (AEA) analogue, plays a neuroprotective role in neurodegenerative diseases and cerebrovascular diseases. Several studies have demonstrated that the endocannabinoids systems (ECS) are involved in the neuroprotective effects against cerebral ischemic injury. Oxygen-glucose deprivation (OGD)-induced neuronal injury elevated the levels of endocannabinoids and activated ECS. This research was conducted to investigate the neuroprotective effect of NST against OGD-induced neuronal injury in cultured primary cortical neurons and the potential mechanism involved. Cortical neurons were treated with NST at indicate concentrations for 30min prior to injury and OGD injured neurons were incubated with normal conditions for 0-24h. The best neuroprotective effect of NST against OGD-induced injury occurred at 10μM. All data indicated that the neuroprotective effect of NST against OGD-induced injury resulted from blocking anandamide membrane transporter (AMT) (IC₅₀=11.74nM) and inhibiting fatty acid amide hydrolase activity (FAAH) (IC₅₀=16.54nM). Our findings demonstrated that NST has an important role in cerebral ischemic injury pathological progression through activating cannabinoid receptors by inhibiting AEA inactivation system. These data suggested a potential role for NST in the therapeutic consideration of cerebral ischemic injury. However, inhibition of AEA inactivation system may provide a neuroprotective effect during cerebral ischemic injury.

Peroxisome proliferator-activated receptors (PPAR) downregulate the expression of pro-inflammatory molecules in an experimental model of myocardial infarction

Myocardial infarction (MI) has been associated with an inflammatory response and a rise in TNF-α, interleukin (IL)-1β, and IL-6. Peroxisome proliferator-activated receptors (PPARs) promote a decreased expression of inflammatory molecules. We aimed to study whether PPAR stimulation by clofibrate decreases inflammation and reduces infarct size in rats with MI. Male Wistar rats were randomized into 3 groups: control, MI + vehicle, and MI + clofibrate (100 mg/kg). Treatment was administered for 3 consecutive days, previous to 2 h of MI. MI induced an increase in protein expression, mRNA content, and enzymatic activity of inducible nitric oxide synthase (iNOS). Additionally, MI incited an increased expression of matrix metalloproteinase (MMP)-2 and MMP-9, intercellular adhesion molecule (ICAM)-1, and IL-6. MI also elevated the nuclear content of nuclear factor-κB (NF-κB) and decreased IκB, both in myocyte nuclei and cytosol. Clofibrate treatment prevented MI-induced changes in iNOS, MMP-2 and MMP-9, ICAM-1, IL-6, NF-κB, and IκB. Infarct size was smaller in clofibrate-treated rats compared to MI-vehicle animals. In silico analysis exhibited 3 motifs shared by genes from renin-angiotensin system, PPARα, iNOS, MMP-2 and MMP-9, ICAM-1, and VCAM-1, suggesting a cross regulation. In conclusion, PPARα-stimulation prevents overexpression of pro-inflammatory molecules and preserves viability in an experimental model of acute MI.

Prophylactic Subacute Administration of Zinc Increases CCL2, CCR2, FGF2, and IGF-1 Expression and Prevents the Long-Term Memory Loss in a Rat Model of Cerebral Hypoxia-Ischemia

Prophylactic subacute administration of zinc decreases lipoperoxidation and cell death following a transient cerebral hypoxia-ischemia, thus suggesting neuroprotective and preconditioning effects. Chemokines and growth factors are also involved in the neuroprotective effect in hypoxia-ischemia. We explored whether zinc prevents the cerebral cortex-hippocampus injury through regulation of CCL2, CCR2, FGF2, and IGF-1 expression following a 10 min of common carotid artery occlusion (CCAO). Male rats were grouped as follows: (1) Zn96h, rats injected with ZnCl2 (one dose every 24 h during four days); (2) Zn96h + CCAO, rats treated with ZnCl2 before CCAO; (3) CCAO, rats with CCAO only; (4) Sham group, rats with mock CCAO; and (5) untreated rats. The cerebral cortex-hippocampus was dissected at different times before and after CCAO. CCL2/CCR2, FGF2, and IGF-1 expression was assessed by RT-PCR and ELISA. Learning in Morris Water Maze was achieved by daily training during 5 days. Long-term memory was evaluated on day 7 after learning. Subacute administration of zinc increased expression of CCL2, CCR2, FGF2, and IGF-1 in the early and late phases of postreperfusion and prevented the CCAO-induced memory loss in the rat. These results might be explained by the induction of neural plasticity because of the expression of CCL2 and growth factors.

Differential hypoxic tolerance is mediated by activation of heat shock response and nitric oxide pathway

The fall in ambient oxygen pressure in high-altitude milieu elicits a wide range of physiological responses in the myocardium, which may differ from individual to individual. This condition, known as hypobaric hypoxia, invokes the cardioprotective heat shock response. The present study focuses on the role played by this ubiquitous response in mediating a differential tolerance to acute hypoxic stress. Sprague Dawley rats were exposed to simulated hypoxia equivalent to 223 mmHg pressure, screened on the basis of time taken for onset of a characteristic hyperventilatory response, and categorized as susceptible (<10 min), normal (10-25 min), or tolerant (>25 min). The tolerant animals displayed a significant upregulation of heat shock protein (Hsp)70/HSPA, evident through immunohistochemical staining of the cardiac tissue. The increased expression of transcription factor heat shock factor-1 led to the downstream activation of other chaperones, including Hsp90/HSPC, Hsp60/HSPD1, and Hsp27/HSPB1. The higher induction of HSPs in tolerant animals contributed to higher nitric oxide synthesis mediated by both endothelial nitric oxide synthase and inducible nitric oxide synthase activation. Conversely, susceptible animals showed significantly higher expression of the proinflammatory markers tumor necrosis factor alpha and nuclear factor kappa-light-chain enhancer of activated B cells in the myocardium. Evaluation of circulatory stress markers identified increased levels of reactive oxygen species, corticosterone and endothelin-1 in the susceptible animals highlighting their vulnerability to hypoxic stress. The heat shock response, through the action of chaperones and enhanced NO generation thus contributes substantially to the ability to sustain survival under acute sub lethal hypoxia.

Melatonin improves cerebrovascular function and decreases oxidative stress in chronically hypoxic lambs

Chronic hypoxia during gestation and delivery results in oxidative stress and cerebrovascular dysfunction in the neonate. We assessed whether melatonin, a potent antioxidant and potential vasodilator, improves the cerebral vascular function in chronically hypoxic neonatal lambs gestated and born in the highlands (3600 m). Six lambs received melatonin (1 mg/kg per day oral) and six received vehicle, once a day for 8 days. During treatment, biometry and hemodynamic variables were recorded. After treatment, lambs were submitted to a graded FiO2 protocol to assess cardiovascular responses to oxygenation changes. At 12 days old, middle cerebral arteries (MCA) were collected for vascular reactivity, morphostructural, and immunostaining evaluation. Melatonin increased fractional growth at the beginning and improved carotid blood flow at all arterial PO2 levels by the end of the treatment (P < 0.05). Further, melatonin treatment improved vascular responses to potassium, serotonin, methacholine, and melatonin itself (P < 0.05). In addition, melatonin enhanced the endothelial response via nitric oxide-independent mechanisms in isolated arteries (162 ± 26 versus 266 ± 34 AUC, P < 0.05). Finally, nitrotyrosine staining as an oxidative stress marker decreased in the MCA media layer of melatonin-treated animals (0.01357 ± 0.00089 versus 0.00837 ± 0.00164 pixels/μm2 , P < 0.05). All the melatonin-induced changes were associated with no systemic cardiovascular alterations in vivo. In conclusion, oral treatment with melatonin modulates cerebral vascular function, resulting in a better cerebral perfusion and reduced oxidative stress in the neonatal period in chronically hypoxic lambs. Melatonin is a potential therapeutic agent for treating cerebrovascular dysfunction associated with oxidative stress and developmental hypoxia in neonates.

Upregulation of cytoprotective defense mechanisms and hypoxia-responsive proteins imparts tolerance to acute hypobaric hypoxia

Exposure to high altitude is a well-known environmental stress with physiological and metabolic consequences, with the major stressor being hypobaric hypoxia. The disruption in cellular homeostasis elicits several acute and chronic adaptations designed to diminish the stress imposed by the hypoxic insult. Highly conserved cellular machinery protects the myocardium from damage under reduced oxygen tension. In the present study, adult Sprague-Dawley rats were exposed to an altitude of 9754 m in a decompression chamber and screened on the basis of the time taken for onset of gasping. The animals were grouped as susceptible (<10 min), normal (10-25 min), and tolerant (>25 min). Histologically, susceptible animals showed increased myocardial inflammation and infiltration and greater CK-MB activity. These animals showed a three-fold increase in reactive oxygen species levels and subsequent oxidative damage to proteins and lipids as compared to control unexposed group. In tolerant animals, the damage was minimal. The resistance to damage in these animals was possibly due to enhanced myocardial antioxidant enzymes, catalase and superoxide dismutase. A significantly higher expression of HIF-1α and its responsive genes, including EPO, HO-1, and GLUT1, was seen in tolerant animals, although VEGF expression was enhanced in the susceptible group. Cytoprotective chaperones, HSP70 and HSP90, were elevated in the tolerant animals. The differential expression of these hypoxia-responsive molecules may thus act as potential biochemical markers for screening and identifying individuals susceptible to environmental stress.

Clofibrate PPARα activation reduces oxidative stress and improves ultrastructure and ventricular hemodynamics in no-flow myocardial ischemia

Peroxisome proliferator-activated receptors (PPAR) play a critical physiological role in energy homeostasis, in inflammation, and a protective role in cardiovascular function. We assessed the antioxidant effect of clofibrate-induced Peroxisome proliferator-activated receptor alpha (PPARα) stimulation on ischemic myocardium on myocardial morphology and hemodynamics. Male Wistar rats (300 g) were distributed into the following groups: (1) Sham, (2) myocardial ischemia vehicle treated (MI-V), and (3) myocardial ischemia clofibrate [100 mg/kg/ intraperitoneally) treated (MI-C). Reactive oxygen species (ROS) and lipid peroxidation increased in MI-V, whereas clofibrate prevented this effect. Superoxide dismutase (SOD)-1 and SOD-2 expression increased 4 times upon PPARα stimulation. SOD-1, SOD-2, and catalase activity also increased in response to clofibrate. eNOS mRNA and tetrahydrobiopterin increased in the MI-C group. Clofibrate was able to decrease Angiotensin II (AngII), AngII AT1-receptor, whereas Ang-(1-7) and AngII AT2-receptor expression increased. Assessment of myocardial morphology and cardiac function show that clofibrate improved histological features and hemodynamic parameters. Our results suggest that PPARα stimulation by clofibrate increases the antioxidant defense, leading to improved cardiac function.

Effect of subchronic hypobaric hypoxia on oxidative stress in rat heart

We examined the effect of subchronic hypobaric hypoxia in rat heart. Adult male Sprague-Dawley rats were exposed at 25,000 ft for different time periods (2 and 5 days). Susceptibility of their hearts to oxidative stress as well as modulation in gene expression was evaluated. The results showed a crosstalk between reactive oxygen species (ROS) and nitric oxide (NO), initial response was accompanied by increase in ROS generation and development of oxidative stress as confirmed by increased lipid peroxidation, protein oxidation and accumulation of 2, 4-dinitrophenyl hydrazine and 4-hydroxy-2-nonenal adducts. At the same time, glutathione activity decreased; however, antioxidant enzymatic activities of superoxide dismutases, glutathione-S-transferase, and glutathione peroxidase rose in response to 5-days hypoxia. Interestingly, NO level increased till 5 days, however ROS decreased after 5 days; this observation suggests that ROS/NO balance plays an important role in cardioprotection. This observation is further supported by upregulation of antioxidant genes hemeoxygenase (HO-1) and metallothionein (MT). In addition, hypoxia also induces gradual upregulation of hypoxia-inducible transcription factor (HIF-1α), which in turn induces the expression of adaptive genes erythropoiesis, vascular endothelial growth factor, glucose transporter-1, nitric oxide synthase. Collectively, our data suggests a reciprocal regulation of ROS and NO and this effect is mediated by the increase in antioxidant proteins HO-1 and MT. Along with this HIF-1-mediated induction of various cardioprotective genes also plays an important role in acclimatization.

Augmentation of aerobic respiration and mitochondrial biogenesis in skeletal muscle by hypoxia preconditioning with cobalt chloride

High altitude/hypoxia training is known to improve physical performance in athletes. Hypoxia induces hypoxia inducible factor-1 (HIF-1) and its downstream genes that facilitate hypoxia adaptation in muscle to increase physical performance. Cobalt chloride (CoCl₂), a hypoxia mimetic, stabilizes HIF-1, which otherwise is degraded in normoxic conditions. We studied the effects of hypoxia preconditioning by CoCl₂ supplementation on physical performance, glucose metabolism, and mitochondrial biogenesis using rodent model. The results showed significant increase in physical performance in cobalt supplemented rats without (two times) or with training (3.3 times) as compared to control animals. CoCl₂ supplementation in rats augmented the biological activities of enzymes of TCA cycle, glycolysis and cytochrome c oxidase (COX); and increased the expression of glucose transporter-1 (Glut-1) in muscle showing increased glucose metabolism by aerobic respiration. There was also an increase in mitochondrial biogenesis in skeletal muscle observed by increased mRNA expressions of mitochondrial biogenesis markers which was further confirmed by electron microscopy. Moreover, nitric oxide production increased in skeletal muscle in cobalt supplemented rats, which seems to be the major reason for peroxisome proliferator activated receptor-gamma coactivator-1α (PGC-1α) induction and mitochondrial biogenesis. Thus, in conclusion, we state that hypoxia preconditioning by CoCl₂ supplementation in rats increases mitochondrial biogenesis, glucose uptake and metabolism by aerobic respiration in skeletal muscle, which leads to increased physical performance. The significance of this study lies in understanding the molecular mechanism of hypoxia adaptation and improvement of work performance in normal as well as extreme conditions like hypoxia via hypoxia preconditioning.

Protective Effect of Pharmacological Preconditioning of Total Flavones of Abelmoschl Manihot on Cerebral Ischemic Reperfusion Injury in Rats

The present study was to investigate the effect of pharmacological preconditioning of total flavones of Abelmoschl Manihot (TFA) on cerebral ischemic reperfusion injury in rats. Rat cerebral ischemia/reperfusion injury was induced by occluding the right middle cerebral artery (MCA). The infarct size was determined by staining with 2,3,5-triphenyl tetrazalium chloride (TTC). The serum malonaldehyde (MDA), nitric oxide (NO) and lactate dehydrogenase (LDH) levels were measured by using spectrophotometry; Inducible NO synthase (iNOS) mRNA expression was detected by RT-PCR method. The percentage of cerebral infarction volume was 28.1 ± 0.8 in the model group, while TFA or nimodipine (Nim) pretreatment 36 hours prior to the ischemic insult significantly decreased the infarction volume. Increases of serum LDH activity and MDA level were observed after ischemia/reperfusion, but these changes were inhibited in rats pretreated with either TFA (20, 40, 80, 160 mg/kg) or Nim, indicating a delayed protective effect of TFA preconditioning on cerebral ischemic reperfusion injury. In addition, the serum NO level and the cerebral iNOS mRNA were up-regulated, suggesting a possible mechanism for the protective effect of TFA pretreatment on cerebral ischemic reperfusion injury.

Carnosic acid attenuates renal injury in an experimental model of rat cisplatin-induced nephrotoxicity

Nephrotoxicity is one of the serious dose limiting side effects of cisplatin when used in the treatment of various malignant conditions. Accumulating evidence suggests that oxidative stress caused by free radicals and apoptosis of renal cells contributes to the pathogenesis of cisplatin-induced nephrotoxicity. Present study was aimed to explore the effect of carnosic acid, a potent antioxidant, against cisplatin induced oxidative stress and nephrotoxicity in rats. A single dose of cisplatin (7.5mg/kg) caused marked renal damage, characterized by a significant (P<0.05) increase in serum creatinine, blood urea nitrogen (BUN) and relative weight of kidney with higher kidney MDA (malondialdehyde), tROS (total reactive oxygen species), caspase 3, GSH (reduced glutathione) levels and lowered tissue nitrite, SOD (superoxide dismutase), CAT (catalase), GSH-Px (glutathione peroxidase), GR (glutathione reductase) and GST (glutathione S-transferase) levels compared to normal control. Carnosic acid treatment significantly (P<0.05) attenuated the increase in lipid peroxidation, caspase-3 and ROS generation and enhanced the levels of reduced glutathione, tissue nitrite level and activities of SOD, CAT, GSH-Px, GR and GST compared to cisplatin control. The present study demonstrates that carnosic acid has a protective effect on cisplatin induced experimental nephrotoxicity and is attributed to its potent antioxidant and antiapoptotic properties.

Effect of clofibrate on vascular reactivity in a model of high blood pressure secondary to aortic coarctation

The aims of this study were to identify the effect of clofibrate administration in the development of high blood pressure secondary to aortic coarctation (AoCo) and to assess its effect on vascular reactivity. Three experimental groups of rats were used: sham-operated, aortic coarctated vehicle-treated (AoCo-V), and aortic coarctated clofibrate-treated (AoCo-C100). The rats were treated for seven days. Blood pressure was measured, and the vascular response to angiotensin II (AngII), norepinephrine (NE), and acetylcholine (ACh) were evaluated in aortic rings. The activity and expression of endothelial nitric oxide synthase (eNOS) was also evaluated. The major findings of this study include the following: AoCo induced a rise in blood pressure, and this effect was attenuated by clofibrate. The vascular response to AngII was higher in aortic rings from the AoCo-V group compared to the Sham-V or AoCo-C100 groups. ACh-elicited vasorelaxation was lower in the arteries of AoCo-V rats than Sham-V or AoCo-C100, while it was comparable between the Sham-V and AoCo-C100 groups. In every case, vasorelaxation was dependent on NO. However, the ACh-induced release of NO as well as NOS activity and expression were reduced in the arteries of AoCo-V rats. Clofibrate maintained normal NOS activity and increased eNOS expression. In conclusion, clofibrate administration attenuated the AoCo-induced rise in blood pressure by a mechanism that involves the participation of the NO system at both the NO synthesis and the eNOS protein expression levels. These events improved endothelial function, preserved normal vascular responses to both vasorelaxants and vasoconstrictors, and led to better blood pressure control.

Hypoxic preconditioning facilitates acclimatization to hypobaric hypoxia in rat heart

Objectives

Acute systemic hypoxia induces delayed cardioprotection against ischaemia-reperfusion injury in the heart. As cobalt chloride (CoCl2) is known to elicit hypoxia-like –responses, it was hypothesized that this chemical would mimic the preconditioning effect and facilitate acclimatization to hypobaric hypoxia in rat heart.

Methods

Male Sprague-Dawley rats treated with distilled water or cobalt chloride (12.5 mg Co/kg for 7 days) were exposed to simulated altitude at 7622 m for different time periods (1, 2, 3 and 5 days).

Key findings

Hypoxic preconditioning with cobalt appreciably attenuated hypobaric hypoxia-induced oxidative damage as observed by a decrease in free radical (reactive oxygen species) generation, oxidation of lipids and proteins. Interestingly, the observed effect was due to increased expression of the antioxidant proteins hemeoxygenase and metallothionein, as no significant change was observed in antioxidant enzyme activity. Hypoxic preconditioning with cobalt increased hypoxia-inducible factor 1α (HIF-1α) expression as well as HIF-1 DNA binding activity, which further resulted in increased expression of HIF-1 regulated genes such as erythropoietin, vascular endothelial growth factor and glucose transporter. A significant decrease was observed in lactate dehydrogenase activity and lactate levels in the heart of preconditioned animals compared with non-preconditioned animals exposed to hypoxia.

Conclusions

The results showed that hypoxic preconditioning with cobalt induces acclimatization by up-regulation of hemeoxygenase 1 and metallothionein 1 via HIF-1 stabilization.

Nitric oxide system is involved in hypobaric hypoxia-induced oxidative stress in rat brain

Oxidative stress is involved in memory impairment at high altitude (HA). The aim of the present study was to investigate the involvement of reactive nitrogen species in hippocampus, cortex and striatum of rat brain under simulated HA conditions. Rats were exposed to hypobaric hypoxia (HH) equivalent to 6100 m of HA in an animal decompression chamber for 3, 7, 14 and 21 days. Biochemical estimation of free radicals, nitric oxide (NO) level along with immunoreactivity, reverse transcriptase polymerase chain reaction (RT-PCR) and western blot of neuronal nitric oxide synthase (nNOS), neurodegeneration and DNA fragmentation were studied after HH exposure. The free radicals, NO level, nNOS immunoreactivity (nNOS-IR), nNOS expression, neurodegeneration and DNA fragmentation were increased in hippocampus, cortex and striatum after HH exposure. After 7 and 14 days of HH exposure, the nNOS-IR, nNOS expression, free radical, NO level, neurodegeneration and DNA fragmentation were increased in comparison to 3 or 21 days of HH. The NO system may be involved in increasing oxidative stress and neurodegeneration after HH.

Decreased nitric oxide markers and morphological changes in the brain of arsenic-exposed rats

Epidemiological studies demonstrate an association between chronic consumption of arsenic contaminated water and cognitive deficits, especially when the exposure takes place during childhood. This study documents structural changes and nitrergic deficits in the striatum of adult female Wistar rats exposed to arsenic in drinking water (3 ppm, approximately 0.4 mg/kg per day) from gestation, throughout lactation and development until the age of 4 months. Kainic acid injected animals (10mg/kg, i.p.) were also analyzed as positive controls of neural cell damage. Morphological characteristics of cells, fiber tracts and axons were analyzed by means of light microscopy as well as immunoreactivity to neuronal nitric oxide synthase (nNOS). As nitrergic markers, nitrite/nitrate concentrations, nNOS levels and expression of nNOS-mRNA were quantified in striatal tissue. Reactive oxygen species (ROS) and lipid peroxidation (LPx) were determined as oxidative stress markers. Arsenic exposure resulted in moderate to severe alterations of thickness, organization, surrounding space and shape of fiber tracts and axons, while cell bodies remained healthy. These anomalies were not accompanied by ROS and/or LPx increases. By contrast, except the expression of nNOS-mRNA, all nitrergic markers including striatal nNOS immunoreactivity presented a significant decrease. These results indicate that arsenic targets the central nitrergic system and disturbs brain structural organization at low exposure levels.

Quantitative immunohistochemical analysis of nitric oxide synthases and apoptosis regulator proteins in the fetal rat brain following maternal uterine artery ligation

The purpose of this study was to determine the relation between nitric oxide synthases (calcium-independent iNOS and calcium-dependent eNOS) and apoptosis regulator proteins (anti-apoptotic Bcl-2, pro-apoptotic p53) of fetal rat brain in experimental intrauterine growth retardation (IUGR) model via quantitative immunohistochemistry. Cortical zone of parietal cerebral cortex and ventricular zone of third ventricle were studied following bilateral uterine artery ligation on gestational day 18. Significant increase in iNOS immunoreactivity was determined in parietal cerebral cortex and ventricular zones as eNOS immunoreactivity increased in ventricular zone of IUGR group. Bcl-2 expression was significantly decreased in ventricular zone; whereas cortical zone of IUGR group expressed p53 immunoreactivity.

High altitude memory impairment is due to neuronal apoptosis in hippocampus, cortex and striatum

Cognitive and neuropsychological functions have been impaired at high altitude and the effects depend on altitude and duration of stay. However, the neurobiological mechanism of this impairment is poorly understood especially exposure to different duration. Aim of the present study was to investigate the changes of behavior, biochemistry and morphology after exposure to different duration of hypobaric hypoxia. The rats were exposed continuously to a simulated high altitude of 6100m for 3, 7, 14 and 21 days in an animal decompression chamber. Spatial reference memory was tested by Morris water maze. The oxidative stress markers like free radicals, NO, lipid peroxidation, LDH activity and antioxidant systems like GSH, GSSG, GPx, GR, SOD were estimated from cortex, hippocampus and striatum. The morphological changes, neurodegeneration, DNA fragmentation and mode of cell death have also been studied. It was observed that the spatial reference memory was significantly affected after exposure to hypobaric hypoxia. Increased oxidative stress markers along with decreased effectiveness of antioxidant system were also observed in hypoxia-exposed animals. Further pyknotic, shrunken, tangle-like neurons were observed in all these regions after hypoxia and neurodegeneration, DNA fragmentation and apoptosis were also observed in all the three regions. But after 21 days of exposure, the spatial memory was improved along with improvement of antioxidant activities. Our result suggests that the apoptotic death may be involved in HA-induced memory impairment and after 7 days of exposure the effect was more pronounced but after 21 days of exposure recovery was observed.

The increase in zinc levels and upregulation of zinc transporters are mediated by nitric oxide in the cerebral cortex after transient ischemia in the rat

The transient occlusion of cerebral arteries causes an increase in zinc levels in the brain, which is associated with a production of nitric oxide (NO). The types of zinc transporters (ZnT) involved in zinc homeostasis in the cerebral cortex after hypoxia-ischemia are not completely known. We studied the effect of the transient occlusion (10 min) of the common carotid artery (CCA) on NO-induced zinc levels, ZnT mRNA expression, and cell-death markers in the cerebral cortex-hippocampus of the rat. Nitrites, zinc, and lipoperoxidation were quantified by colorimetric methods, ZnT expression was determined by RT-PCR, caspase-3 by ELISA and immunohistochemistry, and histopathological alterations by H&E staining. After restoration of the blood flow, the basal levels of NO and zinc increased in a biphasic manner over time, but the peaks of NO levels appeared earlier (2 h and 24 h) than those of zinc (6 h and 36 h). Upregulation of ZnT1, ZnT2, and ZnT4 mRNAs was determined after 8-h postreperfusion, but ZnT3 RNA levels were unaffected. Lipoperoxidation and caspase-3 levels were also increased, and necrosis and apoptosis were present at 24 h postreperfusion. All the effects determined were prevented by l-nitro-arginine methyl ester injected 1 h before the occlusion of the CCA. Our results suggest that the upregulation of ZnT1, ZnT2, and ZnT4 was to decrease the cytosolic zinc levels caused by NO after transient occlusion of the CCA, although this was unable to lead to physiological levels of zinc and to prevent cell damage in the cerebral cortex-hippocampus of the rat.

Spatiotemporal neuronal signaling by nitric oxide: diffusion-reaction modeling and analysis

Nitric oxide (NO) is a neurotransmitter strikingly different from others. It is able to diffuse isotropically regardless of intervening cellular or membrane structures; and it exhibits a surprisingly diverse range of biochemical activity. NO diffusion and reactions affect the nervous system significantly. At present there is no effective technique for detecting them in vivo in real time, whereas computational modeling and simulation helps us gain insight into them. Existing models and simulations for the purpose, however, are inadequate as only the diffusion or only the reactions have been considered. For a comprehensive study of the gaseous neurotransmitter NO, both the diffusion and biochemical reactions should be taken into consideration. This paper, where NO diffusion and reactions are considered as a whole system, presents a spatiotemporal analysis of NO diffusion-reaction, taking the case with brain hypoxia as an example. The analysis is illustrated with a diffusion-reaction model and graphic simulation, which particularly describe how the concentration of oxygen (O2) affects NO signaling in a neuron involved in brain hypoxia.

Increased nitric oxide levels and nitric oxide synthase isoform expression in the cerebellum of the taiep rat during its severe demyelination stage

We have previously reported progressive reactive astrocytes in the cerebellum of taiep rats, one of the most regions affected by demyelination, and activation of cerebellar glial cells in vitro. Based on the hypothesis that activated glial cells produce high levels of reactive nitrogen intermediates, we assessed the production of nitric oxide (NO) and the expression of the three NO synthases (NOS) in the cerebellum of 6-month-old taiep rats. A significant 40% increase of NO levels was measured in taiep rats when compared with controls. The protein and mRNA levels of the three NOS isoforms were also significantly increased. In contrast to controls, immunostaining assays against nNOS or iNOS showed an increased number of immunoreactive glial cells in the granular layer (nNOS) and Purkinje layer (iNOS) of cerebellum of taiep rats. Microglia-macrophages and both CD4- and CD8-immunoreactive cells were observed in cerebellar white matter of taiep rats only, thus suggesting other possible cell sources of those NOSs. Differences in the cellular location for eNOS immunoreactivity were not observed. The enhanced levels of NO, NOS proteins, mRNAs, and NOS immunoreactivities in glial cells and microglia strongly suggest glial activation together with the professional immune cells can aggravate the demyelination of aged taiep rats.

Neurotensin polyplex as an efficient carrier for delivering the human GDNF gene into nigral dopamine neurons of hemiparkinsonian rats

Recently we showed that the neurotensin polyplex is a nanoparticle carrier system that targets reporter genes in nigral dopamine neurons in vivo. Herein, we report its first practical application in experimental parkinsonism, which consisted of transfecting dopamine neurons with the gene coding for human glial cell line-derived neurotrophic factor (hGDNF). Hemiparkinsonism was induced in rats by a single dose of 6-hydroxydopamine (30 microg) into the ventrolateral part of the striatum. We showed that transfection of the hGDNF gene into the substantia nigra of rats 1 week after the neurotoxin injection produced biochemical, anatomical, and functional recovery from hemiparkinsonism. RT-PCR analysis showed mRNA expression of exogenous hGDNF in the transfected substantia nigra. Western blot analysis verified transgene expression by recognizing the flag epitope added at the C-terminus of the hGDNF polypeptide, which was found mainly in dopamine neurons by double immunofluorescence techniques. These data indicate that the neurotensin polyplex holds great promise for the neuroprotective therapy of Parkinson disease.

Hypobaric hypoxia induces oxidative stress in rat brain

High altitude exposure results in decreased partial pressure of oxygen and an increased formation of reactive oxygen and nitrogen species (RONS), which causes oxidative damage to lipids, proteins and DNA. Exposure to high altitude appears to decrease the activity and effectiveness of antioxidant enzyme system. The antioxidant system is very less in brain tissue and is very much susceptible to hypoxic stress. The aim of the present study was to investigate the time dependent and region specific changes in cortex, hippocampus and striatum on oxidative stress markers on chronic exposure to hypobaric hypoxia. The rats were exposed to simulated high altitude equivalent to 6100 m in animal decompression chamber for 3 and 7 days. Results indicate an increase in oxidative stress as seen by increase in free radical production, nitric oxide level, lipid peroxidation and lactate dehydrogenase levels. The magnitude of increase in oxidative stress was more in 7 days exposure group as compared to 3 days exposure group. The antioxidant defence system such as reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and reduced/oxidized glutathione (GSH/GSSG) levels were significantly decreased in all the three regions. The observation suggests that the hippocampus is more susceptible to hypoxia than the cortex and striatum. It may be concluded that hypoxia differentially affects the antioxidant status in the cortex, hippocampus and striatum.

Hindlimb claudication reflects impaired nitric oxide-dependent revascularization after ischemia

Although vascular remodeling is important in preventing tissue damage and restoring muscle function, there is no evidence of a relationship between vascular remodeling and muscle function after peripheral vascular occlusion. Nitric oxide (NO) has been implicated in the process of vascular remodeling in hindlimb ischemia. Thus, development of alterations in hindlimb gait after ischemia may be associated with impaired nitric oxide-dependent, vascular blood flow recovery. We evaluated hindlimb gait as an index of ischemia-induced revascularization and tested the effects of NO synthase inhibition on both hindlimb blood flow and hindlimb gait locomotion. After 14 days of ischemia, the ischemic hindlimb showed no significant differences in gait locomotion compared to the sham-operated hindlimb. However, hindlimb ischemia drastically reduced hindlimb blood flow from 46+/-3 mL/min/100 g to 12+/-2 mL/min/100 g which reverted to 33+/-5 mL/min/100 g after 14 days of ischemia. eNOS mRNA expression levels at 3, 7, 14, and 28 days after initiation of ischemia, were increased by 50+/-5%, 100+/-10%, 140+/-8% and 270+/-12% respectively and eNOS protein expression levels at 7, 14, and 28 days, were increased by 28+/-3%, 62+/-6% and 80+/-16% respectively. However, eNOS inhibition caused by l-NAME treatment prevented blood flow recovery and correction of abnormal gait locomotion in rats. Thus, the duration of the stride-swing phase increased and the stride length decreased. The knee joint angle decreased during flexion and extension with eNOS inhibition. In conclusion, ischemia-induced revascularization is associated with recovery of both hindlimb blood flow and normal gait locomotion. Moreover, prevention of NO synthesis, a key messenger in ischemia-induced revascularization, is associated with impairment in hindlimb locomotion. Thus, gait locomotion represents a functional model that could be used to evaluate the degree of ischemia-induced revascularization.

Enhanced locomotor activity in adult rats with neonatal administration ofN-omega-nitro-L-arginine

Nitric oxide (NO) is a neuronal messenger molecule that plays important roles in the development, maintenance, and functional modifications of brain circuits. We investigated whether the NO levels at different postnatal day (P) periods of the brain develop interference with the locomotion in a novel environment during the postpuberal age (P60). First, using the determination of the nitrite accumulation, we evaluated whether treatment with the NO-synthase inhibitor N-nitro-L-arginine (L-NNA) during different neonatal ages (P1 to P3, P4 to P6, and P7 to P9) affected the levels of NO activity in different regions in the neonatal brain of the rat. We then evaluated whether the locomotor activity in the adult rat (P60) is affected by the blocking of the neonatal NO-activity during a specific period of the development of the nervous system. Neonatal rats with L-NNA administration at P4 to P6 and P7 to P9 show a significant decrease in the levels of NO activity in all the brain regions. However, the blocking of NO synthesis during the neonatal period between P4 to P6 produced an increase in the locomotion after puberty. These data suggest that during a specific step in the development of the brain, the NO levels may play a critical role in the structures that control the spontaneous locomotion in a novel environment after puberty.

Vasoconstriction caused by cocaine is enhanced by sodium salicylate: is inducible nitric oxide synthase mRNA related?

We have previously found that sodium salicylate (NaSal), injected into chicken eggs at nontoxic doses used for quantifying hydroxyl free radicals in hearts and brains of embryos, caused or exacerbated hemorrhages and dramatically reduced hatchability when combined with cocaine (Coc). It has also been reported that inducible nitric oxide synthase (iNOS) gene expression is altered in brain in response to vascular damage and inflammation. In this study we measured diameters of membrane-bound blood vessels (BV) before and after pretreatment with saline (NaCl) or NaSal (100 mg/kg egg), followed by infusion of either NaCl or Coc HCl (total of 67.5 mg/kg egg) during 15 min. Brains and hearts of the embryos were then analyzed for iNOS messenger RNA (mRNA) concentrations. Coc caused vasoconstriction that was significant 5 min postinfusion (5 min PI) of the entire dose (ie after 67.5 mg/kg egg). Significant vasoconstriction was evident within 5 min in the group injected with NaSal followed by infusion with Coc (ie after 22.5 mg Coc/kg egg). Expression of iNOS mRNA was significantly increased only in the brains of the group exposed to NaSal plus Coc, and the increase was inversely related to BV diameter. These data are discussed in relation to effects of salicylate upon prostanoid synthesis and/or nitric oxide synthesis via iNOS inhibition and their possible relationship to Coc-associated cerebral vascular and/or cardiovascular events in abusing humans.

Evidence in vitro of glial cell priming in the taiep rat

Cultured glial cells from the cerebellum of 15-day-old taiep rats produced NO, increased iNOS levels, up-regulated iNOS expression and promoted TNF release when stimulated with LPS and IFNgamma. These responses were much greater than in control cells. In taiep glial cells, NO production and iNOS levels and expression induced by the co-stimulatory signal were resistant to the inhibitory effect of TGFbeta1. The glial cell priming might have been generated by oligodendrocyte alteration in taiep rats.