Regulation of Intestinal P-Glycoprotein by Gamma-Ray Irradiation: Impacts on Transporter Expression and Oxidative...

P-glycoprotein (P-gp), a key efflux drug transporter which plays a pivotal role in the in vivo pharmacokinetics of medications, undergoes alterations in expression and function following radiation exposure that can impact drug metabolism and therapeutic efficacy. Current research has found that clinical doses of radiation can affect the expression of drug transporters, while the underlying mechanisms associated with single high-dose irradiation remain to be thoroughly elucidated. This study investigates the effects of gamma-ray irradiation on the expression and transport activity of P-glycoprotein (P-gp) in various cell lines and murine small-intestinal tissues, and preliminarily explores the underlying regulatory mechanisms, thereby providing an experimental basis for research into drug transport abnormalities and interventions associated with radiation injury. Four different cell lines and male C57BL/6J mice were exposed to γ-ray irradiation from a ⁶⁰Co source. P-gp gene expression was quantitatively analyzed, combined with the relative expression levels of proteins in intestinal cells and small-intestinal tissues and relevant physiological parameters. Furthermore, a Transwell intestinal epithelial cell barrier model and an in vivo mouse intestinal perfusion model were established. Using digoxin as a P-gp specific substrate, a quantitative LC-MS method was developed to assess P-gp transport activity after irradiation. Finally, transcriptome sequencing analysis of mouse small-intestinal tissue was performed, and oxidative-stress-related pathways were preliminarily detected. At the cellular level, the mRNA expression was significantly upregulated, peaking at 4.19 times that of the control group, while protein expression was also significantly upregulated, reaching a peak of approximately 2.50 times that of the control; at the animal level, the peak upregulation for mRNA and protein was 2.09-fold and 1.95-fold, respectively. Transport activity also gradually increased over time after irradiation. At the animal level, transcriptome analysis further revealed that changes in pathways such as oxidative stress and immune inflammatory responses may be jointly related to radiation-induced intestinal P-gp regulation mechanisms. Gamma-ray irradiation was associated with significant upregulation of P-gp expression and was consistent with enhanced efflux activity suggestive of P-gp involvement in various cell lines and mouse small-intestinal tissues. Radiation exposure induced intestinal damage and oxidative stress, and was associated with activation of the Nrf2/HO-1 antioxidant signaling pathway.