Hyperbaric oxygen effects on neuronal apoptosis associations in a traumatic brain injury rat model

The neuroprotective mechanisms of hyperbaric oxygen (HBO) therapy on traumatic brain injury (TBI) remain unclear, especially neuronal apoptosis associations such as the expression of tumor necrosis factor alpha (TNF-α), transforming growth-interacting factor (TGIF), and TGF-β1 after TBI. The aim of this study was to investigate the neuroprotective effects of HBO therapy in a rat model of TBI.

The experimental rats were randomly divided into three groups as follows: TBI + normobaric air (21% O₂ at one absolute atmosphere), TBI + HBO, and sham-operated normobaric air. The TBI + HBO rats received 100% O₂ at 2.0 absolute atmosphere for 1 h immediately after TBI. Local and systemic TNF-α expression, neuropathology, levels of the neuronal apoptosis-associated proteins TGIF and TGF-β1, and functional outcome were evaluated 72 h after the onset of TBI.

Compared to the TBI control groups, the running speed of rats on the TreadScan after TBI was significantly attenuated by HBO therapy. The TBI-induced local and systemic TNF-α expression, neuronal damage score, and neuronal apoptosis were also significantly reduced by HBO therapy. Moreover, HBO treatment attenuated the expression of TGIF but increased TGF-β1 expression in neurons.

We concluded that treatment of TBI with HBO during the acute phase of injury can decrease local and systemic proinflammatory cytokine TNF-α production, resulting in neuroprotective effects. We also suggest that decreased levels of TGIF and increased levels of TGF-β in the injured cortex leading to decreased neuronal apoptosis is one mechanism by which functional recovery may occur.