Effects of repetitive hyperbaric oxygen therapy on neuroprotection in middle cerebral artery occlusion rats

Optimized oxygen therapy improves sleep deprivation-induced cardiac dysfunction through gut microbiota

Adequate sleep is of paramount importance for relieving stress and restoring mental vigor. However, the adverse physiological and pathological responses resulting from sleep insufficiency or sleep deprivation (SD) are becoming increasingly prevalent. Currently, the impact of sleep deficiency on gut microbiota and microbiota-associated human diseases, especially cardiac diseases, remains controversial. Here, we employed the following methods: constructed an experimental sleep-deprivation model in mice; conducted 16S rRNA sequencing to investigate the changes in gut microbiota; through fecal microbiota transplantation (FMT) experiments, transplanted fecal microbiota from sleep-deprived mice to other mice; established an environment with a 30% oxygen concentration to explore the therapeutic effects of oxygen therapy on gut microbiota-associated cardiac fibrosis and dysfunction; and utilized transcriptome data to study the underlying mechanisms of oxygen therapy. The results revealed that: sleep-deprived mice exhibited weakness, depression-like behaviors, and dysfunction in multiple organs. Pathogenic cardiac hypertrophy and fibrosis occurred in sleep-deprived mice, accompanied by poor ejection fraction and fractional shortening. 16S rRNA sequencing indicated that sleep deprivation induced pathogenic effects on gut microbiota, and similar phenomena were also observed in mice that received fecal microbiota from sleep-deprived mice in the FMT experiments. The environment with a 30% oxygen concentration effectively alleviated the pathological impacts on cardiac function. Transcriptome data showed that oxygen therapy targeted several hypoxia-dependent pathways and inhibited the production of cardiac collagen. In conclusion, these results demonstrate the significance of sufficient sleep for gut microbiota and may represent a potential therapeutic strategy, where the oxygen environment exerts a protective effect on insomniacs through gut microbiota.

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.

The Optimized Protocol of Hyperbaric Oxygen Therapy For Sudden Sensorineural Hearing Loss

OBJECTIVE

This study aimed to determine the optimal protocol of hyperbaric oxygen therapy (HBOT) according to various treatment settings for sudden sensorineural hearing loss (SSNHL).

METHODS

A 112 patients with SSNHL were enrolled in this prospective study. All patients were treated with systemic steroid therapy, intratympanic steroid therapy, and HBOT. According to the pressure and duration of HBOT (10 sessions in total), the patients were divided into three groups: group 1, 2.5 atmospheres absolute (ATA) for 1 h; group 2, 2.5 ATA for 2 h; and group 3, 1.5 ATA for 1 h. The pure-tone average (PTA), word discrimination score (WDS), and mean gain were compared.

RESULTS

A total of 105 patients completed the 3-month follow-up, and 6 patients were excluded. Differences among groups were found in PTA, WDS, and mean gain. In the post-hoc analysis, group 3 had significantly lower WDS and mean gain than groups 1 and 2; however, group 2 showed no significant differences from group 1. The proportion of patients with hearing recovery after treatment was significantly higher in group 1 (57.6%) and group 2 (58.8%) than in group 3 (31.3%).

CONCLUSIONS

When HBOT (10 sessions) was combined with corticosteroids as the initial therapy for SSNHL, a higher pressure (1.5 ATA vs. 2.5 ATA) provided better treatment results; however, increasing the duration (1 h vs. 2 h) under 2.5 ATA did not result in a significant difference. Therefore, HBOT for SSNHL may be performed at 2.5 ATA for 1 h in 10 sessions. Laryngoscope, 133:383-388, 2023.

The SDF1-CXCR4 Axis Is Involved in the Hyperbaric Oxygen Therapy-Mediated Neuronal Cells Migration in Transient Brain Ischemic Rats

Neurogenesis is a physiological response after cerebral ischemic injury to possibly repair the damaged neural network. Therefore, promoting neurogenesis is very important for functional recovery after cerebral ischemic injury. Our previous research indicated that hyperbaric oxygen therapy (HBOT) exerted neuroprotective effects, such as reducing cerebral infarction volume. The purposes of this study were to further explore the effects of HBOT on the neurogenesis and the expressions of cell migration factors, including the stromal cell-derived factor 1 (SDF1) and its target receptor, the CXC chemokine receptor 4 (CXCR4). Thirty-two Sprague–Dawley rats were divided into the control or HBO group after receiving transient middle cerebral artery occlusion (MCAO). HBOT began to intervene 24 h after MCAO under the pressure of 3 atmospheres for one hour per day for 21 days. Rats in the control group were placed in the same acrylic box without HBOT during the experiment. After the final intervention, half of the rats in each group were cardio-perfused with ice-cold saline followed by 4% paraformaldehyde under anesthesia. The brains were removed, dehydrated and cut into serial 20μm coronal sections for immunofluorescence staining to detect the markers of newborn cell (BrdU⁺), mature neuron cell (NeuN⁺), SDF1, and CXCR4. The affected motor cortex of the other half rats in each group was separated under anesthesia and used to detect the expressions of brain-derived neurotrophic factor (BDNF), SDF1, and CXCR4. Motor function was tested by a ladder-climbing test before and after the experiment. HBOT significantly enhanced neurogenesis in the penumbra area and promoted the expressions of SDF1 and CXCR4. The numbers of BrdU⁺/SDF1⁺, BrdU⁺/CXCR4⁺, and BrdU⁺/NeuN⁺ cells and BDNF concentrations in the penumbra were all significantly increased in the HBO group when compared with the control group. The motor functions were improved in both groups, but there was a significant difference between groups in the post-test. Our results indicated that HBOT for 21 days enhanced neurogenesis and promoted cell migration toward the penumbra area in transient brain ischemic rats. HBOT also increased BDNF expression, which might further promote the reconstructions of the impaired neural networks and restore motor function.

Exploring Hyperoxia Effects in Cancer-From Perioperative Clinical Data to Potential Molecular Mechanisms

Increased inspiratory oxygen concentration is constantly used during the perioperative period of cancer patients to prevent the potential development of hypoxemia and to provide an adequate oxygen transport to the organs, tissues and cells. Although the primary tumours are surgically removed, the effects of perioperative hyperoxia exposure on distal micro-metastases and on circulating cancer cells can potentially play a role in cancer progression or recurrence. In clinical trials, hyperoxia seems to increase the rate of postoperative complications and, by delaying postoperative recovery, it can alter the return to intended oncological treatment. The effects of supplemental oxygen on the long-term mortality of surgical cancer patients offer, at this point, conflicting results. In experimental studies, hyperoxia effects on cancer biology were explored following multiple pathways. In cancer cell cultures and animal models, hyperoxia increases the production of reactive oxygen species (ROS) and increases the oxidative stress. These can be followed by the induction of the expression of Brain-derived neurotrophic factor (BDNF) and other molecules involved in angiogenesis and by the promotion of various degrees of epithelial mesenchymal transition (EMT).