Oxidative stress is generated during the pathophysiology of endometriosis (EMT). Hydrogen (H2) has been demonstrated as a gas antioxidant. The aim of the present study is to evaluate the protective effect of H2 on EMT in rats. Sprague Dawley rats with surgically induced EMT were randomly received the inhalation of 67% H2-33% oxygen (O2) mixture (1 h/d, 4 weeks) immediately after the EMT surgery or 4 weeks after the operation. The mixture of 67% N2-33% O2 was also used to exclude the possible influence of the increased O2. Eight weeks after the operation, the endometrial tissues were weighted and analyzed using histology, immunohistochemistry, and real-time polymerase chain reaction. Several antioxidant enzymes and malondialdehyde were also measured in serum and tissue. The estrous cycles were monitored for H2 safety. The results showed that both profiles of high-dose H2 breathing reduced the size of the endometrial explants, inhibited cell proliferation, improved superoxide dismutase, glutathione peroxidase, malondialdehyde, and catalase activities, and regulated the expression of matrix metalloproteinase 9 and cyclooxygenase 2. However, inhalation of the same dose of nitrogen failed to show the protection. High-dose H2 breathing did not change the normal estrous cyclicity. These results suggest that 67% H2-33% O2 breathing has a beneficial effect on EMT model rats, and inhalation of a high dose of H2 could be a potential method applied in clinical practice.
He Y, Shi JZ, Zhang RJ, et al. Effects of hydrogen gas inhalation on endometriosis in rats. Reprod Sci. 2017 Feb;24(2):324-331.