The synergistic effect of pulsed red light and leonurus inhibits primary dysmenorrhea induced by oxytocin in mice by modulating calcium signaling and inhibiting inflammatory responses.

Despite increasing evidence suggesting that red light photobiomodulation (R-PBM) and leonurus play important roles in analgesic and anti-inflammatory processes, data on their combined effect on primary dysmenorrhea (PD) are scarce. In this study, we reported the pain assessment of red light at various modes combined with leonurus on the oxytocin-induced model of PD mice. The combined intervention of pulsed R-PBM and leonurus decreased pain responses and PGF/PGE levels, alleviated uterine swelling and inflammatory infiltration, enhanced antioxidant levels (T-AOC, GSH-PX, SOD), and reduced lipid peroxidation (MDA, LPO) in the uterus, with its synergistic effect surpassing either treatment alone or the combination of continuous wave R-PBM with leonurus. Transcriptomic analysis demonstrated significant changes in differentially expressed genes associated with calcium signaling (Cav1, Cacna1c, Kcnmb1, Cnn1, and Myh11) and inflammatory response (Ptgs2, Jun, Fos, IL1rn, and IL17b) in the combination group, with concurrent downregulation of MLCK, COX-2, p-JNK/JNK, and IL17b protein levels, and upregulation of IL1rn, suggesting that the combined intervention of pulsed R-PBM and leonurus may alleviate pain through disruption of calcium homeostasis and induction of ROS-mediated inflammatory responses. Metabolomics studies of plasma revealed significant changes in lipid metabolism after the combined intervention, consistent with the transcriptomic findings. Hence, pulsed R-PBM combined leonurus has the potential to be an effective therapeutic approach for PD, as well as an alternative option for painful and inflammatory diseases; however, further exploration of its underlying mechanism is still necessary.