Regulation of Apoptosis and Oxidative Stress by Oral Boswellia Serrata Gum Resin Extract in a Rat Model of Endometriosis

Endometriosis (EMS) is a gynecological disease characterized by inflammation, oxidative stress, and apoptosis dysregulation. This study aims to evaluate the effect of Boswellia serrata gum resin extract (BS) on the endometriotic lesions in a rat model of endometriosis. We divided female rats into three groups, including Sham, EMS, EMS + BS. In the EMS and EMS + BS groups, pathology was induced and after 7 days by the abdominal high-frequency ultrasound (hfUS) analysis the presence of the endometriotic lesions was confirmed. Subsequently, the EMS + BS group was administered with BS (100 mg/Kg) daily for another 7 days. At the end of the experiment, the hfUS analysis was repeated and the animals were sacrificed to evaluate the size and histoarchitecture of the endometriotic implants. Pelvic ultrasound showed increased size of the endometriotic lesions in the Endo group, while BS administration reduced the lesion size. The macroscopic analysis confirmed the reduced area and volume of the endometriotic lesions of the EMS + BS group. The histological analysis showed reduced characteristic of ectopic stroma and glands in the animals treated with BS. Western blot analyses were conducted to evaluate the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. BS increases the expression of Nfr2 in the nucleus and the expression of its downstream antioxidant proteins NQO-1 and HO-1. Moreover, it reduced lipid peroxidation and increased glutathione (GSH) levels, and glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities. BS administration also restored the impaired apoptotic pathway in the lesions by reducing Bcl-2 expression and increasing Bax and cleaved caspase 9 levels. The BS apoptotic effect was also confirmed by the cleavage of PARP, another specific marker of apoptosis, and by the TUNEL assay. Our results show that BS administration resulted in an effective and coordinated suppression of Endo owing to its antioxidant and antiapoptotic activities.