Structural changes of neurons in hippocampus from infantile rats exposed to hyperbaric oxygen

To investigate if hyperbaric oxygen (HBO) may induce structural changes of neurons in hippocampus from infantile rats and if the changes are reversible. Methods: All 27 healthy SD infantile rats were exposed to HBO ( 0.25 MPa) or hyperbaric air (HBA) for 1 to 3 courses (10 days as 1 course). The hippocampus was taken at the end of each course to observe its morphology by light microscope and electron microscope. Results: HBO exposure induced capillary dilation, nuclear membrane winding or blurring and some mitochondria swelling with its crista blurring in neurons. The changes occurred after 1 course exposure and became significant with time. Most of the changes recovered 20 days after stopping exposure. No change was found after HBA exposure. Conclusions: Long-term HBO exposure can cause capillary dilation and ultrastructural injury of neurons in hippocampus from infantile rats. The damage is not serious, but reversible.