This study aimed to explore the characteristic role of Puerariae Lobatae Radix(PLR) in Gegen Decoction for the treatment of primary dysmenorrhea(PD). Estrogen(E_2) was combined with oxytocin to establish a mouse model of PD. The mice were randomly divided into a normal group, a model group, a Gegen Decoction group, a PLR-free Gegen Decoction group, a PLR group, and a positive drug group(ibuprofen). Writhing response times and writhing incubation of mice in each group were tested by behavio-ral assessment, and the serum levels of prostaglandin F_(2α)(PGF_(2α)), prostaglandin E_2(PGE_2), E_2, and progesterone(PROG) were detected by ELISA kits. Western blot method was adopted to detect cyclooxygenase-2(COX-2) and estrogen receptor alpha(ER_α) expression levels in uterine tissues. Doppler ultrasound was employed to detect changes in uterine artery blood flow in mice, including peak systolic blood flow velocity(maximum velocity), end-diastolic velocity(minimum velocity), peak systolic blood flow velocity/end-diastolic velocity(S/D), pulsatility index(PI), and resistive index(RI). Histopathological changes in the uterus were detected by HE staining. Based on the oxytocin-induced isolated uterine contraction model, the effects of Gegen Decoction, PLR-free Gegen Decoction, and PLR on the amplitude, frequency, and activity of isolated uterine contraction were compared to investigate the role of PLR in Gegen Decoction for the treatment of PD. The results showed that compared with the Gegen Decoction group, the PLR-free Gegen Decoction improved the indicators of PD except for E_2 content, ER_α expression, and uterine artery blood flow. PLR could significantly down-regulate the serum content of E_2 and the protein expression of uterine ER_α, and improve the uterine artery blood flow. The data suggested that PLR, as the sovereign drug of Gegen Decoction, might function in Gegen Decoction for the treatment of PD by mediating E_(2 )and improving the uterine artery blood flow.
Keywords: Doppler ultrasound; Gegen Decoction; Puerariae Lobatae Radix(PLR); primary dysmenorrhea; uterine artery blood flow.