Evaluation of the oxidative effect of long-term repetitive hyperbaric oxygen exposures on different brain regions of rats

Research progress on high-concentration oxygen therapy after cerebral hemorrhage

Recently, the role of high-concentration oxygen therapy in cerebral hemorrhage has been extensively discussed. This review describes the research progress in high-concentration oxygen therapy after cerebral hemorrhage. High-concentration oxygen therapy can be classified into two treatment methods: hyperbaric and normobaric high-concentration oxygen therapy. Several studies have reported that high-concentration oxygen therapy uses the pathological mechanisms of secondary ischemia and hypoxia after cerebral hemorrhage as an entry point to improve cerebral oxygenation, metabolic rate, cerebral edema, intracranial pressure, and oxidative stress. We also elucidate the mechanisms by which molecules such as Hypoxia-inducible factor 1-alpha (HIF-1α), vascular endothelial growth factor, and erythropoietin (EPO) may play a role in oxygen therapy. Although people are concerned about the toxicity of hyperoxia, combined with relevant literature, the evidence discussed in this article suggests that as long as the duration, concentration, pressure, and treatment interval of patients with cerebral hemorrhage are properly understood and oxygen is administered within the treatment window, it can be effective to avoid hyperoxic oxygen toxicity. Combined with the latest research, we believe that high-concentration oxygen therapy plays an important positive role in injuries and outcomes after cerebral hemorrhage, and we recommend expanding the use of normal-pressure high-concentration oxygen therapy for cerebral hemorrhage.

Hyperbaric Oxygen Therapy Attenuated the Motor Coordination and Cognitive Impairment of Polyglutamine Spinocerebellar Ataxia SCA17 Mice

Spinocerebellar ataxias (SCAs) are a large and diverse group of autosomal-dominant neurodegenerative diseases. No drugs have been approved for these relentlessly progressive and fatal SCAs. Our previous studies indicate that oxidative stress, neuroinflammation, and neuronal apoptosis are elevated in the SCA17 mice, which are the main therapeutic targets of hyperbaric oxygen treatment (HBOT). HBOT is considered to be an alternative and less invasive therapy for SCAs. In this study, we evaluated the HBOT (2.2 ATA for 14 days) effect and the persistence for the management of SCA17 mice and their wild-type littermates. We found HBOT attenuated the motor coordination and cognitive impairment of SCA17 mice and which persisted for about 1 month after the treatment. The results of several biochemistry and liver/kidney hematoxylin and eosin staining show the HBOT condition has no obvious toxicity in the mice. Immunostaining analyses show that the neuroprotective effect of HBOT could be through the promotion of BDNF production and the amelioration of neuroinflammation. Surprisingly, HBOT executes different effects on the male and female SCA17 mice, including the reduction of neuroinflammation and activation of CaMKII and ERK. This study suggests HBOT is a potential alternative therapeutic treatment for SCA17. Accumulated findings have revealed the similarity in disease pathomechanisms and possible therapeutic strategies in polyQ diseases; therefore, HBOT could be an optional treatment as well as the other polyQ diseases.

Effects of hyperbaric oxygen therapy on autistic behaviors and GRIN2B gene expression in valproic acid-exposed rats

Introduction

Autism is a complex neurodevelopmental condition characterized by deficits in social interaction, communication, and restricted repetitive behaviors. Hyperbaric oxygen therapy (HBOT) has emerged as a potential treatment for autism, although its effects on behavior and gene expression are not well understood. The GRIN2B gene, known for its involvement in encoding a glutamate receptor subunit crucial for neuron communication and associated with autism, was a focus of this study.

Methods

Using a rat model induced by prenatal exposure to valproic acid, we examined the impact of HBOT on autism-like behaviors and GRIN2B gene expression. Male Wistar rats were categorized into four groups: control, VPA (valproic acid-exposed), VPA+HBOT [2 atmosphere absolute (ATA)], and VPA+HBOT (2.5 ATA). The rats underwent several behavioral tests to assess social behavior, anxiety, stereotype and exploratory behaviors, and learning. Following the behavioral tests, the HBOT groups received 15 sessions of HBOT at pressures of 2 and 2.5 (ATA), and their behaviors were re-evaluated. Subsequently, real-time PCR was employed to measure GRIN2B gene expression in the frontal lobe.

Results

Our results indicated that HBOT significantly increased social interaction and exploratory behaviors in VPA-exposed rats, alongside elevated GRIN2B gene expression in their frontal lobe.

Discussion

Our findings imply that HBOT might have a potential role in ameliorating autism-related behaviors in the VPA rat model of autism through potential modulation of GRIN2B gene expression. However, additional research is essential to fully comprehend the underlying mechanisms and refine the HBOT protocol for optimizing its effectiveness in improving autism-related symptoms.

Hyperbaric oxygen alleviates selective domains of cognitive and motor deficits in female 5xFAD mice

Treatment of Alzheimer's disease (AD) has been limited to managing of symptoms or anti-amyloid therapy with limited results and uncertainty. Seeking out new therapies that can reverse the effects of this devastating disease is important. Hyperbaric oxygen (HBO) therapy could be such a candidate as it has been shown to improve brain function in certain neurological conditions. Furthermore, the role sex plays in the vulnerability/resilience to AD remains equivocal. An understanding of what makes one sex more vulnerable to AD could unveil new pathways for therapy development. In this study, we investigated the effects of HBO on cognitive, motor, and affective function in a mouse model of AD (5xFAD) and assessed protein oxidation in peripheral tissues as a safety indicator. The motor and cognitive abilities of 5xFAD mice were significantly impaired. HBO therapy improved cognitive flexibility and associative learning of 5xFAD females but not males, but HBO had no effect other aspects of cognition. HBO also reversed AD-related declines in balance but had no impact on gait and anxiety-like behavior. HBO did not affect body weights or oxidative stress in peripheral tissues. Our study provides further support for HBO therapy as a potential treatment for AD and emphasizes the importance of considering sex as a biological variable in therapeutic development. Further investigations into the underlying mechanisms of HBO's sex-specific responses are warranted, as well as optimizing treatment protocols for maximum benefits.

Compare the effectiveness of extracorporeal shockwave and hyperbaric oxygen therapy on enhancing wound healing in a streptozotocin-induced diabetic rodent model

Studies have revealed that both extracorporeal shock-wave therapy (ESWT) and hyperbaric oxygen therapy (HBOT) can accelerate wound healing. This study aimed to compare the effectiveness of ESWT and HBOT in enhancing diabetic wound healing. A dorsal skin defect in a streptozotocin-induced diabetes rodent model was used. Postoperative wound healing was assessed once every 3 days. Histologic examination was performed with hematoxylin and eosin staining. Proliferation marker protein Ki-67 (Ki-67), endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF), and 8-hydroxy-2-deoxyguanosine (8-OHdG) were evaluated with immunohistochemical (IHC) staining. The wound area was significantly reduced in the ESWT and HBOT groups compared to that in the diabetic controls. However, the wound healing time was significantly increased in the HBOT group compared to the ESWT group. Histological findings showed a statistical increase in neovascularization and suppression of the inflammatory response by both HBOT and ESWT compared to the controls. IHC staining revealed a significant increase in Ki-67, VEGF, and eNOS but suppressed 8-OHdG expression in the ESWT group compared to the HBOT group. ESWT facilitated diabetic wound healing more effectively than HBOT by suppressing the inflammatory response and enhancing cellular proliferation and neovascularization and tissue regeneration.

The potential of hyperbaric oxygen as a therapy for neurodegenerative diseases

The World Health Organization estimates that by the year 2040, neurodegenerative diseases will be the second leading cause of death in developed countries, overtaking cancer-related deaths and exceeded only by cardiovascular disease-related death. The search for interventions has therefore become paramount to alleviate some of this burden. Based on pathways affected in neurodegenerative diseases, hyperbaric oxygen treatment (HBOT) could be a good candidate. This therapy has been used for the past 50 years for conditions such as decompression sickness and wound healing and has been shown to have promising effects in conditions associated with neurodegeneration and functional impairments. The goal of this review was to explore the history of hyperbaric oxygen therapy, its uses, and benefits, and to evaluate its effectiveness as an intervention in treating neurodegenerative diseases. Additionally, we examined common mechanisms underlying the effects of HBOT in different neurodegenerative diseases, with a special emphasis on epigenetics.

Does Hyperbaric Oxygenation Improve Athletic Performance?

ABSTRACT

Šet, V, and Lenasi, H. Does hyperbaric oxygenation improve athletic performance? J Strength Cond Res 37(2): 482-493, 2023-Hyperbaric oxygen (HBO) has been suggested to affect oxygen availability and performance, and delay the onset of fatigue. Many mechanisms of HBO-induced alterations have been proposed, including modulation of various metabolic pathways, and the antioxidant defense mechanisms. As exercise per se affects similar aspects, it is tempting to speculate that simultaneous application of both, exercise and HBO might have synergistic effects. The aim of this review was to search through the currently available literature and evaluate the effect of acute exposure to HBO on exercise performance, potential effects of a combination of HBO and physical training, and to elucidate some possible mechanisms behind. We conducted searches in the PubMed and Scopus databases (search term: "hyperbaric" AND "oxygen" AND "exercise") and in relevant hyperbaric textbook and assessed potentially eligible full texts for details. Meta-analysis could not be performed because of a few available and rather heterogeneous studies. Twenty-seven studies were included in the final assessment (14 on exercise during HBO, 9 on exercise following HBO, 4 on applying HBO during recovery and rest between exercise bouts, and 3 on a combination of HBO and training). The results are contradictory, showing either positive or none ergogenic effects. There is some risk of bias and placebo effect. Discrepant findings of the available studies might partly be explained by different protocols applied, both regarding HBO and exercise intensity and regimen. There is a need for further research with well-designed trials to evaluate the effect of HBO on performance before recommending it to routine use in athletes.

Hyperbaric Oxygen Treatment: Effects on Mitochondrial Function and Oxidative Stress

Hyperbaric oxygen treatment (HBOT)—the administration of 100% oxygen at atmospheric pressure (ATA) greater than 1 ATA—increases the proportion of dissolved oxygen in the blood five- to twenty-fold. This increase in accessible oxygen places the mitochondrion—the organelle that consumes most of the oxygen that we breathe—at the epicenter of HBOT’s effects. As the mitochondrion is also a major site for the production of reactive oxygen species (ROS), it is possible that HBOT will increase also oxidative stress. Depending on the conditions of the HBO treatment (duration, pressure, umber of treatments), short-term treatments have been shown to have deleterious effects on both mitochondrial activity and production of ROS. Long-term treatment, on the other hand, improves mitochondrial activity and leads to a decrease in ROS levels, partially due to the effects of HBOT, which increases antioxidant defense mechanisms. Many diseases and conditions are characterized by mitochondrial dysfunction and imbalance between ROS and antioxidant scavengers, suggesting potential therapeutic intervention for HBOT. In the present review, we will present current views on the effects of HBOT on mitochondrial function and oxidative stress, the interplay between them and the implications for several diseases.

Molecular and Therapeutic Aspects of Hyperbaric Oxygen Therapy in Neurological Conditions

In hyperbaric oxygen therapy (HBOT), the subject is placed in a chamber containing 100% oxygen gas at a pressure of more than one atmosphere absolute. This treatment is used to hasten tissue recovery and improve its physiological aspects, by providing an increased supply of oxygen to the damaged tissue. In this review, we discuss the consequences of hypoxia, as well as the molecular and physiological processes that occur in subjects exposed to HBOT. We discuss the efficacy of HBOT in treating neurological conditions and neurodevelopmental disorders in both humans and animal models. We summarize by discussing the challenges in this field, and explore future directions that will allow the scientific community to better understand the molecular aspects and applications of HBOT for a wide variety of neurological conditions.

Hyperbaric Oxygen Treatment is Associated with Lipid Inflammatory Response Assessed Uding Serum Platelet Activating Factor

Hyperbaric oxygen (HBO) treatment is generally a relatively safe therapy for various conditions. However, there are some adverse side effects. For example HBO tratment has been reported to increase the production of free oxygen radicals(FRs). Furthermore, to our knowledge, no previous clinical research has been carried out to study the involvement of platelet-activating factor(PAF)as the lipid oxidative stressor in patients undergoing HBO treatment. A total of 45 patients included in this study were first given clinical assessment and laboratory measurements before starting HBO treatment and were named group baseline. After the HBO treatment, the same clinical and laboratory measurements from the same patients were repeated and this was named group sesion >20.As expected, long-term HBO treatment had no effect on oxLDL (oxidized low-density lipoprotein), a lipid oxidative stress(OS) marker. However, the mean PAF values in the second group showed a statistically significant increase compared to their pretreatment values, (P <0. 002).As this is a preliminary study, there is a need for more detailed investigations that demonstrate the association of HBO treatment with the lipid inflammatory response. Therefore, there is need for further clinical study for OS markers such as oxLDL in HBO treatment. Clinical prospective studies are required to confirm our laboratory findings.

Hyperbaric oxygen therapy: Antimicrobial mechanisms and clinical application for infections

Hyperbaric oxygen therapy (HBOT) is a treatment procedure that involves breathing 100% O₂ for a certain time and under a certain pressure. HBOT is commonly administrated as a primary or alternative therapy for different diseases such as infections. In this paper, we reviewed the general aspect of HBOT procedures, the mechanisms of antimicrobial effects and the application in the treatment of infections. Parts of the antimicrobial effects of HBOT are believed to result of reactive from the formation of reactive oxygen species (ROS). It is also said that HBOT enhances the antimicrobial effects of the immune system and has an additive or synergistic effect with certain antimicrobial agents. HBOT has been described as a useful procedure for different infections, particularly in deep and chronic infections such as necrotizing fasciitis, osteomyelitis, chronic soft tissue infections, and infective endocarditis. The anti-inflammation property of HBOT has demonstrated that it may play a significant role in decreasing tissue damage and infection expansion. Patients treated by HBOT need carful pre-examination and monitoring. If safety standards are strictly tracked, HBOT can be considered a suitable procedure with an apt rate of complication.

Acute Hyperbaric Oxygenation, Contrary to Intermittent Hyperbaric Oxygenation, Adversely Affects Vasorelaxation in Healthy Sprague-Dawley Rats due to Increased Oxidative Stress

The present study was aimed at assessing endothelium-dependent vasorelaxation, at measuring superoxide production in the aorta and femoral artery, and at determining antioxidative enzyme expression and activity in aortas of male Sprague-Dawley rats (N = 135), randomized to an A-HBO₂ group exposed to a single hyperbaric oxygenation session (120′ of 100% O₂ at 2.0 bars), a 24H-HBO₂ group (single session, examined 24 h after exposure), a 4D-HBO₂ group (4 consecutive days of single sessions), and a CTRL group (untreated group). Vasorelaxation of aortic rings in response to acetylcholine (AChIR) and to reduced pO₂ (HIR) was tested in vitro in the absence/presence of NOS inhibitor L-NAME and superoxide scavenger TEMPOL. eNOS, iNOS, antioxidative enzyme, and NADPH oxidase mRNA expression was assessed by qPCR. Serum oxidative stress markers and enzyme activity were assessed by spectrometry, and superoxide production was determined by DHE fluorescence. Impaired AChIR and HIR in the A-HBO₂ group were restored by TEMPOL. L-NAME inhibited AChIR in all groups. Serum oxidative stress and superoxide production were increased in the A-HBO₂ group compared to all other groups. The mRNA expression of iNOS was decreased in the A-HBO₂ and 24H-HBO₂ groups while SOD1 and 3 and NADPH oxidase were increased in the 4D-HBO₂ group. The expression and activity of catalase and glutathione peroxidase were increased in the 4D-HBO₂ group as well. AChIR was NO dependent. Acute HBO₂ transiently impaired vasorelaxation due to increased oxidative stress. Vasorelaxation was restored and oxidative stress was normalized 24 h after the treatment.

Hyperbaric-Oxygen Therapy Improves Survival and Functional Outcome of Acute Severe Intracerebral Hemorrhage

BACKGROUND

Prognosis of spontaneous intracerebral hemorrhage (ICH) remains poor worldwide.

AIMS OF THE STUDY

To investigate the effect and optimal protocol for hyperbaric-oxygen therapy (HBOT), and reduce incidence of upper gastrointestinal bleeding (UGIB) in ICH.

METHODS

This prospective, randomized, controlled trial included 565 patients with acute severe ICH. Participants were randomly assigned to a sham-control group (Group A) and four intervention groups: Groups B and C with 2.0 atmospheres absolute (ATA) pressure and HBOT exposure for 60 or 90 sessions, respectively; and Groups D and E with 1.5 ATA for 60 or 90 sessions, respectively. All patients received emergency craniotomy with hematoma evacuation. Outcome measures were modified Barthel Index (MBI) and modified Rankin Scale (mRS) scores, mortality rates at follow-up six months. UGIB rates were assessed as potential side effect.

RESULTS

In four intervention groups, MBI and mRS scores were all significantly improved, and mortality rates were all significantly decreased compared with Group A (all p < 0.005). UGIB rates were 39.25, 60.00, 64.49, 36.79, and 34.26% in Groups A, B, C, D, and E, respectively. UGIB rates in Groups B and C were significantly increased compared with Groups A, D and E (all p < 0.005). None of UGIB were clinically significant.

CONCLUSIONS

HBOT significantly improves survival and functional outcomes of ICH. HBOT at 1.5 and 2.0 ATA had the same beneficial effect. A pressure of 1.5 ATA and 60 HBOT exposures represents an optimal protocol for HBOT. Further studies are needed to optimize the protocol per specific patient.

The acute antinociceptive effect of hyperbaric oxygen is not accompanied by an increase in markers of oxidative stress

AIMS

Exposure to hyperbaric oxygen (HBO2) causes an antinociceptive response in mice. However, breathing oxygen (O2) at an elevated pressure can potentially cause oxygen toxicity. The aim of this study was to identify the determinants of HBO2 antinociception and the toxicity profile of HBO2.

MAIN METHODS

Male NIH Swiss mice were assessed for acute antinociceptive responsiveness under room air or 100% O2 at 1.0 or 3.5 atmospheres absolute (ATA), using the acetic acid-induced abdominal constriction test. For the oxygen toxicity test, mice were exposed to 3.5 ATA oxygen for 11min, 60min, and 60min daily for 2days (120min) or 60min daily for 4days (240min), then assessed by analyzing the levels of two oxidative stress markers, MDA (malondialdehyde) and protein carbonyl in brain, spinal cord and lung.

KEY FINDINGS

Only the combination of 100% O2 and 3.5 ATA caused significant antinociception. The antinociceptive effect of 100% O2 was pressure-dependent up to 3.5 ATA. In the oxygen toxicity test, mice exposed to HBO2 for different time intervals had levels of brain, spinal cord and lung MDA and protein carbonyl that were comparable to that of control animals exposed to room air.

SIGNIFICANCE

Treatment with 100% O2 evokes a pressure-dependent antinociceptive effect. Since there was no significant increase in levels of the oxidative stress markers in the tested tissues, it is concluded that HBO2 at 3.5 ATA produces antinociception in the absence of oxidative stress in mice.