Wuzhuyu Decoction relieves hyperalgesia by regulating central and peripheral 5-HT in chronic migraine model rats

Chronic migraine (CM) is a highly disabling and burdensome disease. Wuzhuyu decoction (WZYD), a clinical used formula to treat and prevent episodic migraine and CM, has been reported to relieve the hyperalgesia of CM and increase brainstem and blood serotonin (5-hydroxytryptamine, 5-HT) in migraine model rats in previous studies; yet the mechanism is unclear.This study aimed to observe the hyperalgesia relief effect of WZYD and investigate the mechanistic association with the regulation on central and peripheral 5-HT.WZYD with different doses (3.372, 1.686 and 0.843 g/kg∙d) and the positive drug - sumatriptan (5.83 mg/kg∙3 d) were intragastrically administered in inflammatory soup (IS)-induced CM model rats, respectively. Hyperalgesia was assessed by facial mechanical withdrawal threshold and tail-flick latency. 5-HT was determined by ELISA. Western blot analysis, immunohistochemistry and immunofluorescence determination, and 16S rRNA gene sequencing were performed.WZYD significantly relieved the hyperalgesia by elevating the facial mechanical withdrawal threshold and tail-flick latency. In WZYD groups, increased 5-HT and decreased calcitonin gene-related peptide in both the brainstem and plasma, downregulated TNF-α, IL-1β, and c-fos expression in the brainstem were observed in dose-dependent manner. Interestingly, 5-HT in colon tissues were also observed, which is associated with upregulating tryptophan hydroxylase, serotonin transporter and Piezo1 expression and increasing 5-HT and chromogranin A in enterochromaffin cells. Disorder of the microbiota, function and metabolism was correlated with 5-HT synthesis. WZYD could regulate the abundance of Anaerostipes and Acidifaciens.WZYD has the pharmacological effect on relieving hyperalgesia in CM model rats, possibly by affecting central and peripheral 5-HT.