Si-Wu-Tang ameliorates chemotherapy-induced premature ovarian insufficiency by regulating a signaling pathway in endoplasmic reticulum stress.

Abstract

BACKGROUND: Premature ovarian insufficiency (POI) is a clinically refractory reproductive system disorder. Our previous studies demonstrated that the traditional Chinese herbal formula Si-Wu-Tang (SWT) might ameliorate POI in animal models by improving ovarian angiogenesis, yet the underlying mechanisms remained unclear. PURPOSE: To explore the mechanisms of the traditional Chinese medicine (TCM) formula SWT on human umbilical vein endothelial cells (HUVECs) and animal models of POI. By studying its mechanisms, the research hopes to reveal the connotation of 'nourishing blood and activating blood circulation' in TCM. METHODS: Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was applied to identify the chemical constituents in SWT. In the cell experiment section, a chemotherapy-induced HUVEC injury model was established using 4-hydroperoxy cyclophosphamide (4-OOHCY). Endoplasmic reticulum stress (ERS) and apoptosis levels were detected. Agonists and inhibitors were applied to clarify the regulatory role of SWT on the ERS signaling pathway. In the animal experiment section, rat and mouse models were established using cyclophosphamide (CY), respectively. The modeling and treatment efficacy were assessed by monitoring estrous cycles, ovarian index, histopathological sections, and sex hormone levels. Multiple techniques were employed to detect ERS and apoptosis levels in ovarian tissue and local microvessels. RESULTS: SWT enhanced HUVEC viability, reduced chemotherapy-induced ERS, oxidative stress, and apoptosis levels. It also protected the migration and tube formation abilities of HUVECs. The underlying mechanisms involved SWT downregulating the activation of the PERK/eIF2α/ATF4/CHOP signaling pathway triggered by 4-OOHCY. In POI animal models, SWT restored low body weight, sex hormone levels, follicle count, and ovarian angiogenesis through ameliorating ERS and apoptosis. CONCLUSION: In summary, SWT protected the angiogenesis of HUVEC and POI animal models against chemotherapy-induced injury by regulating the PERK/eIF2α/ATF4/CHOP signaling pathway in ERS.