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The current study was to test an experimental model of actinic lesions in the distal intestine of rats and to determine the possible protective effect of hyperbaric oxygen therapy (HBO2) in radio-induced lesions when concomitantly applied with ionizing radiation. Twenty-four Wistar rats were divided into four groups: G1 (control group); G2 (animals irradiated); G3 (animals irradiated plus HBO2); G4 (only HBO2). The animals were evaluated for 28 days after the end of treatment and then euthanized. The distal intestine was resected for macroscopic and microscopic evaluation and immunohistochemistry. The animals in the G3 group lost weight during the treatment; all of the animals in the G2 group presented macroscopic mucosal lesions up until 28 days; the animals in the other three groups did not present macroscopic lesions. Microscopic mucosal lesions were observed in the specimens of the animals treated with ionizing radiation; in the animals from the G3 and G4 groups the lesions were less intense. For the immunohistochemical analysis, we observed the specimens taken from G3 group animals had more CD34+ cells. The experimental model proved to be useful in causing radio-induced lesions, and concomitantly applied HBO2 is capable of reducing late actinic lesions.

The aim of the present study was to evaluate the effect of hyperbaric oxygen therapy (HBO2) on the healing process of ischemic colonic anastomoses in rats. Forty Wistar rats were divided into four groups: control (Group I), control and HBO2 (Group II), ischemia (Group III), ischemia and HBO2 (Group IV). Ischemia was achieved by clamping four centimeters of the colonic arcade. On the eighth therapy day, the anastomotic region was removed for quantification of hydroxyproline and immunohistochemical determination of metalloproteinases 1 and 9 (MMP1, MMP9). The immunohistochemical studies showed significantly larger metalloproteinase-labeled areas in Group IV compared with Group III for both MMP1 and MMP9 (p < 0.01). This finding points to a higher remodeling activity of the anastomoses in this experimental group. Additionally, animals subjected to hyperbaric oxygen therapy showed both a reduction in interstitial edema and an increase in hydroxyproline concentrations [at the anastomotic site]. Therefore, we conclude that HBO2 is indeed beneficial in anastomotic ischemia.