Effect Of Hyperbaric Oxygen Preconditioning On Endometriosis In Rats And Its Mechanism

BACKGROUND AND AIMEndometriosis?EMS?is a debilitating gynecologic disease which is described by the presence of implanted endometrial tissue outside the uterine cavity with a relatively high prevalence.Although several optional theories have been suggested as the pathophysiological basis of the disease,its etiology remains unclear.Recent studies addressing the pathological characteristics of endometriosis have revealed a vicious cycle in which oxidative stress?OS?is generated during the implantation of the ectopic endometrium and in turn facilitate the disease.Thus,the generation of high amount of reactive oxygen species?ROS?further triggers a state of oxidative stress.Hyperbaric oxygen?HBO?is 100%oxygen administered at an elevated atmospheric pressure.It can be applied to treat a variety of diseases,including traumatic injuries,infections,and decompression sickness.Recent experimental research has reported that hyperbaric oxygen preconditioning?HBO-PC?has the anti-oxidative properties in vitro and in vivo.Because aiming for the reduction of OS as the treatment goal for endometriosis looks promising,we thus wonder whether hyperbaric oxygen preconditioning can provide beneficial effect on endometriosis through regulating the degree of oxidative stress.The aim of the present experiment is to:?1?investigate the effect of hyperbaric oxygen preconditioning on endometriosis in rats to provide theoretical basis to further applications;?2?explore the its mechanism of hyperbaric oxygen preconditioning on endometriosis in rats.MATERIAL AND METHODSThis study is divided into two parts:Part one:24 female adult Sprague-Dawley?SD?rats were used to suffer endometriosis by transplantation of endometrial tissues surgically.Animals were divided as the following before the implantation?n=6 in each group?:?1?EMS;?2?EMS+NBO?normobaric oxygen?;?3?EMS+HBA?hyperbaric air?;?4?EMS+HBO.The total volume of ectopic endometrium and ELISA for IL-6,IL-8,TNF-?and VEGF in peritoneal fluid were measured 4 weeks after the surgical.Additional 20 animals were used to monitor the effect of HBO on estrous cycles.Part two:24 female SD rats with surgically induced endometriosis were randomly received as the following?n=6 in each group?:?1?EMS;?2?EMS+HBO;?3?EMS+HBO+O₂·;?4?EMS+HBO+H₂O₂.4 weeks after the operation,the endometrial tissues were measured and analyzed using histology and immunohistochemistry.The activities of SOD and CAT were also measured in serum and tissue.RESULTSIn our experiment,we found that:?1?compared with EMS group,EMS+HBO group present significant beneficial actions in the evaluation of ectopic endometrial volume?62.5±18.1 vs 36.3±9.2,p<0.05?and ELISA for IL-6?65.2±12.7 vs 58.3±11.2?,IL-8?35.7±5.3 vs 28.8±6.6?,TNF-??17.9±5.3 vs 10.5±2.2?and VEGF?16.3±4.1 vs13.7±4.7?,but EMS+NBO group and EMS+HBA group failed to show the protection;?2?HBO exposure did not change the estrous cycles;?3?compared with EMS group,the activities of SOD?12.0±1.3 vs 20.6±4.3,19.1±4.5,21.9±3.3,p<0.05,respectively?and CAT?8.7±3.5 vs 13.0±5.2,12.3±4.9,11.2±3.6,p<0.05,respectively?were significant evaluated in EMS+HBO,EMS+HBO+O₂·and EMS+HBO+H₂O₂ group,respectively.However,the EMS+HBO+O₂·and EMS+HBO+H₂O₂ group blocks the beneficial of HBO-PC according to the evaluation of ectopic endometrial volume?36.3±9.2 vs 67.5±20.3,55.2±15.6,p<0.05,respectively?,histological score?1.3±0.7 vs 2.4±1.6,2.7±1.0,p<0.05,respectively?and PCNA positive numbers?8.2±5.5 vs 20.4±8.8,17.5±7.5,p<0.05,respectively?.CONCLUSIONHBO-PC can reduce the severity of the endometriosis through regulating oxidative stress in rats.HBO did not change the estrous cycles in female rats.It has the possibility that HBO-PC can be applied in clinical situations for preventing endometriosis in the future.