Abstract
Objective:
This study investigated the antinociceptive effects of chiropractic therapy in a rat model of cold-stimulated primary dysmenorrhea (PD) and explored the mechanism through which it modulates the expression of the transient receptor potential vanilloid 1 (TRPV1) in mast cells (MCs) to ameliorate pain sensitization.
Methods:
Five groups of rats were used: blank, model, chiropractic, sodium cromoglicate (SCG) + chiropractic, and ibuprofen. Following chiropractic intervention, behavioral responses were observed; serum levels of prostaglandin F2α (PGF2α), prostaglandin E2 (PGE2), cyclooxygenase-2 (COX-2), and arginine vasopressin (AVP) were measured via ELISA; uterine mast cell (MC) expression was detected by toluidine blue staining; and Western blotting and RT–qPCR were employed to quantify TRPV1 protein and mRNA expression, respectively, in the uterus, dorsal root ganglion (DRG), and periaqueductal gray (PAG).
Results:
Compared with the blank group, the model group exhibited a shortened writhing latency (P < 0.01). Serum PGF2α, COX-2, and AVP levels were significantly elevated, while PGE2 levels were reduced (P < 0.01). Uterine MC counts and degranulation increased (P < 0.01), and TRPV1 protein and mRNA expression in the uterus, DRG, and PAG increased (P < 0.01). After chiropractic treatment, writhing latency increased (P < 0.01). Serum PGF2α, COX-2, and AVP levels decreased, whereas PGE2 levels increased (P < 0.01). Uterine MC counts and degranulation decreased (P < 0.01, P < 0.05), and TRPV1 protein and mRNA expression in the uterus, DRG, and PAG decreased (P < 0.01).
Conclusion:
Chiropractic therapy alleviates pain hypersensitivity in cold-stimulated PD model rats, potentially by modulating uterine MC activation and subsequently downregulating TRPV1 expression in the uterus, DRG, and PAG.
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