Stachydrine Ameliorates Uterine Hypercontractility in Primary Dysmenorrhea by Targeting the COX-2/PGF2α Pathway

Primary dysmenorrhea (PDM) is a typical gynecologic disease in which uterine contractions and inflammation cause pain. Stachydrine (Sta) possesses multiple pharmacological activities but its effect on PDM has not yet been clarified. In vitro uterine contraction and oxytocin (OT)-induced PDM mouse models were used to evaluate the effect of Sta. Sta (10^-6.5 to 10^-4 mol/L) dose-dependently inhibited spontaneous and OT-induced uterine contractions, with maximum inhibition rates of 47.1% and 40.4%, respectively. This effect was reversed by N-nitro-L-arginine (L-NAME) and indomethacin (Indo), suggesting the involvement of the nitric oxide and prostaglandin pathways. In vivo, Sta (20, 10, 5 mg/kg) significantly reduced writhing episodes, prolonged latency to the first response, and alleviated OT-induced uterine damage and inflammation. Additionally, Sta downregulated cyclooxygenase-2 (COX-2) expression in uterine tissue and decreased serum malondialdehyde (MDA) and prostaglandin F₂α (PGF2α) levels. These findings suggest that Sta alleviates PDM by modulating the COX-2/PGF2α pathway, inhibiting uterine contractions, and reducing inflammation and oxidative stress, making it a promising therapeutic candidate for PDM.