Hyperbaric Oxygen Reduces Oxidative Stress Impairment and DNA Damage and Simultaneously Increases HIF-1α in Ischemia-Reperfusion Acute Kidney Injury.

The central exacerbating factor in the pathophysiology of ischemic-reperfusion acute kidney injury (AKI) is oxidative stress. Lipid peroxidation and DNA damage in ischemia are accompanied by the formation of 3-nitrotyrosine, a biomarker for oxidative damage. DNA double-strand breaks (DSBs) may also be a result of postischemic AKI. γH2AX(S139) histone has been identified as a potentially useful biomarker of DNA DSBs. On the other hand, hypoxia-inducible factor (HIF) is the "master switch" for hypoxic adaptation in cells and tissues. The aim of this research was to evaluate the influence of hyperbaric oxygen (HBO) preconditioning on antioxidant capacity estimated by FRAP (ferric reducing antioxidant power) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assay, as well as on oxidative stress parameter 3-nitrotyrosine, and to assess its effects on γH2AX(S139), HIF-1α, and nuclear factor-κB (NF-κB) expression, in an experimental model of postischemic AKI induced in spontaneously hypertensive rats. The animals were divided randomly into three experimental groups: sham-operated rats (SHAM, n = 6), rats with induced postischemic AKI (AKI, n = 6), and group exposed to HBO preconditioning before AKI induction (AKI + HBO, n = 6). A significant improvement in the estimated glomerular filtration rate, eGFR, in AKI + HBO group (p < 0.05 vs. AKI group) was accompanied with a significant increase in plasma antioxidant capacity estimated by FRAP (p < 0.05 vs. SHAM group) and a reduced immunohistochemical expression of 3-nitrotyrosine and γH2AX(S139). Also, HBO pretreatment significantly increased HIF-1α expression (p < 0.001 vs. AKI group), estimated by Western blot and immunohistochemical analysis in kidney tissue, and decreased immunohistochemical NF-κB renal expression (p < 0.01). Taking all of these results together, we may conclude that HBO preconditioning has beneficial effects on acute kidney injury induced in spontaneously hypertensive rats.

Hyperbaric Oxygenation Prevents Loss of Immature Neurons in the Adult Hippocampal Dentate Gyrus Following Brain Injury.

A growing body of evidence suggests that hyperbaric oxygenation (HBO) may affect the activity of adult neural stem cells (NSCs). Since the role of NSCs in recovery from brain injury is still unclear, the purpose of this study was to investigate the effects of sensorimotor cortex ablation (SCA) and HBO treatment (HBOT) on the processes of neurogenesis in the adult dentate gyrus (DG), a region of the hippocampus that is the site of adult neurogenesis. Ten-week-old Wistar rats were divided into groups: Control (C, intact animals), Sham control (S, animals that underwent the surgical procedure without opening the skull), SCA (animals in whom the right sensorimotor cortex was removed via suction ablation), and SCA + HBO (operated animals that passed HBOT). HBOT protocol: pressure applied at 2.5 absolute atmospheres for 60 min, once daily for 10 days. Using immunohistochemistry and double immunofluorescence labeling, we show that SCA causes significant loss of neurons in the DG. Newborn neurons in the subgranular zone (SGZ), inner-third, and partially mid-third of the granule cell layer are predominantly affected by SCA. HBOT decreases the SCA-caused loss of immature neurons, prevents reduction of dendritic arborization, and increases proliferation of progenitor cells. Our results suggest a protective effect of HBO by reducing the vulnerability of immature neurons in the adult DG to SCA injury.

Hyperbaric Oxygen Preconditioning Upregulates Heme OxyGenase-1 and Anti-Apoptotic Bcl-2 Protein Expression in Spontaneously Hypertensive Rats with Induced Postischemic Acute Kidney Injury.

Renal ischemia and reperfusion (I/R) injury is the most common cause of acute kidney injury (AKI). Pathogenesis of postischemic AKI involves hemodynamic changes, oxidative stress, inflammation process, calcium ion overloading, apoptosis and necrosis. Up to date, therapeutic approaches to treat AKI are extremely limited. Thus, the aim of this study was to evaluate the effects of hyperbaric oxygen (HBO) preconditioning on citoprotective enzyme, heme oxygenase-1 (HO-1), pro-apoptotic Bax and anti-apoptotic Bcl-2 proteins expression, in postischemic AKI induced in normotensive Wistar and spontaneously hypertensive rats (SHR). The animals were randomly divided into six experimental groups: SHAM-operated Wistar rats (W-SHAM), Wistar rats with induced postischemic AKI (W-AKI) and Wistar group with HBO preconditioning before AKI induction (W-AKI + HBO). On the other hand, SHR rats were also divided into same three groups: SHR-SHAM, SHR-AKI and SHR-AKI + HBO. We demonstrated that HBO preconditioning upregulated HO-1 and anti-apoptotic Bcl-2 protein expression, in both Wistar and SH rats. In addition, HBO preconditioning improved glomerular filtration rate, supporting by significant increase in creatinine, urea and phosphate clearances in both rat strains. Considering our results, we can also say that even in hypertensive conditions, we can expect protective effects of HBO preconditioning in experimental model of AKI.

Hyperbaric oxygenation protects the kidney against ischemia-reperfusion injury.

Background: Acute kidney injury (AKI) as a consequence of ischemia is a common clinical event that can lead to unacceptably high morbidity and mortality. Hyperbaric oxygen (HBO2) preconditioning has been shown to prevent ischemia-reperfusion injury (IRI) in different tissues. Objectives: The aim of our study was to compare the effects of HBO2 preconditioning on renal hemodynamics, kidney function and oxidative stress in normotensive and spontaneously hypertensive rats that suffered kidney IRI. Methods: An experiment was performed on Wistar (normotensive) and spontaneously hypertensive rats (SHR). The animals were divided into the following experimental groups: sham-operated rats and rats with or without HBO2 preconditioning 24 hours before post-ischemic AKI induction. Treated rats were placed into experimental HBO2 chambers and exposed to pure oxygen twice a day for two consecutive days (2.026 bar of oxygen) for 60 minutes. AKI was performed the next morning. The right kidney was removed and the renal ischemia was performed by clamping the left renal artery for 45 minutes. Results: In this study, HBO2 preconditioning significantly improved disturbed renal hemodynamics, major markers of kidney function in plasma (creatinine, urea and phosphate) as well as antioxidant enzymes (superoxide dismutase and catalase) activities in erythrocytes after AKI induction. Also, HBO2 preconditioning decreased lipid peroxidation in plasma after ischemic AKI. Positive effects were observed in both strains of rats. Conclusions: Our results suggest that HBO2 treatment improves renal hemodynamic and kidney function and decreases oxidative stress of Wistar and SHR rats with an AKI episode. Furthermore, it also implies that pre-existing hypertension does not affect the beneficial effects of HBO2 preconditioning.

Hyperbaric oxygen preconditioning and the role of NADPH oxidase inhibition in postischemic acute kidney injury induced in spontaneously hypertensive rats.

Renal ischemia/reperfusion injury is a common cause of acute kidney injury (AKI) and hypertension might contribute to the increased incidence of AKI. The purpose of this study was to investigate the effects of single and combined hyperbaric oxygen (HBO) preconditioning and NADPH oxidase inhibition on oxidative stress, kidney function and structure in spontaneously hypertensive rats (SHR) after renal ischemia reperfusion injury. HBO preconditioning was performed by exposing to pure oxygen (2.026 bar) twice a day for two consecutive days for 60 minutes, and 24h before AKI induction. For AKI induction, the right kidney was removed and ischemia was performed by clamping the left renal artery for 45 minutes. NADPH oxidase inhibition was induced by apocynin (40 mg/kg b.m., intravenously) 5 minutes before reperfusion. AKI significantly increased renal vascular resistance and reduced renal blood flow, which were significantly improved after apocynin treatment. Also, HBO preconditioning, with or without apocynin treatment showed improvement on renal hemodynamics. AKI significantly increased plasma creatinine, urea, phosphate levels and lipid peroxidation in plasma. Remarkable improvement, with decrease in creatinine, urea and phosphate levels was observed in all treated groups. HBO preconditioning, solitary or with apocynin treatment decreased lipid peroxidation in plasma caused by AKI induction. Also, combined with apocynin, it increased catalase activity and solitary, glutathione reductase enzyme activity in erythrocytes. While AKI induction significantly increased plasma KIM- 1 levels, HBO preconditioning, solitary or with apocynin decreased its levels. Considering renal morphology, significant morphological alterations present after AKI induction were significantly improved in all treated groups with reduced tubular dilatation, tubular necrosis in the cortico-medullary zone and PAS positive cast formation. Our results reveal that NADPH oxidase inhibition and hyperbaric oxygen preconditioning, with or without NADPH oxidase inhibition may have beneficial effects, but their protective role should be evaluated in further studies.

Repetitive hyperbaric oxygenation attenuates reactive astrogliosis and suppresses expression of inflammatory mediators in the rat model of brain injury.

The exact mechanisms by which treatment with hyperbaric oxygen (HBOT) exerts its beneficial effects on recovery after brain injury are still unrevealed. Therefore, in this study we investigated the influence of repetitive HBOT on the reactive astrogliosis and expression of mediators of inflammation after cortical stab injury (CSI). CSI was performed on male Wistar rats, divided into control, sham, and lesioned groups with appropriate HBO. The HBOT protocol was as follows: 10 minutes of slow compression, 2.5 atmospheres absolute (ATA) for 60 minutes, and 10 minutes of slow decompression, once a day for 10 consecutive days. Data obtained using real-time polymerase chain reaction, Western blot, and immunohistochemical and immunofluorescence analyses revealed that repetitive HBOT applied after the CSI attenuates reactive astrogliosis and glial scarring, and reduces expression of GFAP (glial fibrillary acidic protein), vimentin, and ICAM-1 (intercellular adhesion molecule-1) both at gene and tissue levels. In addition, HBOT prevents expression of CD40 and its ligand CD40L on microglia, neutrophils, cortical neurons, and reactive astrocytes. Accordingly, repetitive HBOT, by prevention of glial scarring and limiting of expression of inflammatory mediators, supports formation of more permissive environment for repair and regeneration.

Hyperbaric oxygenation improves locomotor ability by enhancing neuroplastic responses after cortical ablation in rats.

OBJECTIVE: To investigate whether hyperbaric oxygenation (HBO) can improve the recovery of motor functions in rats after suction ablation of the right sensorimotor cortex. METHODS: The experimental paradigm implies the following groups: Control animals (C), Control + HBO (CHBO), Sham controls (S), Sham control + HBO (SHBO), Lesion group (L), right sensorimotor cortex was removed by suction, Lesion + HBO (LHBO). Hyperbaric protocol: pressure applied 2.5 atmospheres absolute, for 60 minutes, once a day for 10 days. A beam walking test and grip strength meter were used to evaluate the recovery of motor functions. Expression profiles of growth-associated protein 43 (GAP43) and synaptophysin (SYP) were detected using immunohistochemistry. RESULTS: The LHBO group achieved statistically superior scores in the beam walking test compared to the L group. Additionally, the recovery of muscle strength of the affected hindpaw was significantly enhanced after HBO treatment. Hyperbaric oxygenation induced over-expression of GAP43 and SYP in the neurons surrounding the lesion site. CONCLUSIONS: Data presented suggest that hyperbaric oxygen therapy can intensify neuroplastic responses by promoting axonal sprouting and synapse remodelling, which contributes to the recovery of locomotor performances in rats. This provides the perspective for implementation of HBO in clinical strategies for treating traumatic brain injuries.

Hyperbaric oxygenation alters temporal expression pattern of superoxide dismutase 2 after cortical stab injury in rats.

AIM: To evaluate the effect of hyperbaric oxygen therapy (HBOT) on superoxide dismutase 2 (SOD2) expression pattern after the cortical stab injury (CSI). METHODS: CSI was performed on 88 male Wistar rats, divided into control, sham, lesioned, and HBO groups. HBOT protocol was the following: pressure applied was 2.5 absolute atmospheres, for 60 minutes, once a day for consecutive 3 or 10 days. The pattern of SOD2 expression and cellular localization was analyzed using real-time polymerase chain reaction, Western blot, and double-label fluorescence immunohistochemistry. Neurons undergoing degeneration were visualized with Fluoro-Jade®B. RESULTS: CSI induced significant transient increase in SOD2 protein levels at day 3 post injury, which was followed by a reduction toward control levels at post-injury day 10. At the same time points, mRNA levels for SOD2 in the injured cortex were down-regulated. Exposure to HBO for 3 days considerably down-regulated SOD2 protein levels in the injured cortex, while after 10 days of HBOT an up-regulation of SOD2 was observed. HBOT significantly increased mRNA levels for SOD2 at both time points compared to the corresponding L group, but they were still lower than in controls. Double immunofluorescence staining revealed that 3 days after CSI, up-regulation of SOD2 was mostly due to an increased expression in reactive astrocytes surrounding the lesion site. HBOT attenuated SOD2 expression both in neuronal and astroglial cells. Fluoro-Jade®B labeling showed that HBOT significantly decreased the number of degenerating neurons in the injured cortex. CONCLUSION: HBOT alters SOD2 protein and mRNA levels after brain injury in a time-dependent manner.

[Hyperbaric oxygen therapy of angiopathic changes in patients with inherited gene imbalance].

INTRODUCTION: Phenotype match inherited by genes is in most cases present in monozygotic twins. Their phenotypic resemblance is unfortunately characterized by strong susceptibility for the development of chronic non-infectious diseases. One of the most common non-infectious chronic diseases that are phenotipically represented in twins is diabetes mellitus. Genetic imbalance is, in most cases, placed in 2, 3, 7, 8, 11, 12, 19 and 20 chromosomal pair of the human genome. CASE OUTLINE: This study describes a pair of monozygotic twins, aged 54, who were diagnosed for diabetes type 2 ten years earlier. The first patient had trophic changes of muscles and skin tissues of the lower limb, and a necrotic wound on his right leg tibial region with the claudication distance of 50 m. After arteriography, he was referred by a vascular surgeon for hyperbaric oxygen therapy (HBO). HBO protocol implied 70 min. application of 100% oxygen at 2.5 absolute atmospheres. After the first series of HBO therapies consisting of 20 HBO treatments, claudication was eliminated and the necrotic wound healed. Next, surgical aortofemoral bypass was done. During the second HBO treatment, his monozygotic twin brother presented with angiopathic changes due to diabetes. In both patients, biochemical parameters corresponded to the expected level for diabetes type 2 imbalance, and the localization of the chromosomal defect (placed on 3, 11 and 19 chromosomal pair) was also in accordance with the respective disorder. After they were included into next 10 HBO treatments, Doppler imaging of the major arteries of limbs revealed normal findings. CONCLUSION: Identical genetic impairment in monozygotic twins can lead to identical somatic changes with resultant consequences. HBO treatment of such patients associated with other therapeutic procedures (conducted by diabetologist, vascular surgeon and physiatrist) can postpone or prevent irreversible changes occurring due to blood vessel disorders.

Hyperbaric oxygenation as a possible therapy of choice for infertility treatment.

Endometrial sonographic and color doppler features can be used to predict the occurrence of pregnancy in natural or stimulated cycles. Implantation will usually only take place if the endometrium has reach a certain stage of vascularisation and development. The aim of this study was to evaluate endometrial development -- endometrial thickness and reflectivity , subendometrial, endometrial and uterine perfusion, after hyperbaric oxygenation, using transvaginal color doppler. During a three years period 32 women with unexplained infertility were entered into a randomised study. The patients were treated in multiplaced HAUX chamber at pressure of 2.3 ATA during 70 minutes, 7 days consecutively beginning with day 5th of menstrual cycle. The evaluation of effects of hyperbaric oxygen therapy was carried out by transvaginal color doppler sonography which was continuously used starting from 8th day of menstrual cycle until the ovulation in the cycles when the therapy was applied , one month before and one month after the therapy. Folliculometry in the cycles when hyperbaric oxygen therapy at 2.3 ATA was applied, indicated an excellent response of endometrium. Thickness of endometrium at the time of ovulation was 11.0 +/- 2.6 mm. Desirable quality of endometrium was significantly better in the cycle when HBO therapy had been applied (p< 0.001). The doppler flowmetry of the uterine arteries indicated that the uterine blood vessel resistance was slightly higher than expected. Mapping of subendometrial blood vessels in the cycles covered by hyperbaric oxygen therapy showed the intensive capillary network of endometrium with low resistance Ri< 0.45. The oxygen used under higher pressure -- oxygen as a drug , may have an extraordinary significance for better outcome of pregnancy implantation by improving endometrial receptivity. If endometrial receptivity is conditioned by adequate vascularisation and oxygenation, then hyperbaric oxygen therapy is the treatment of choice.