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

Background: 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.

Purpose: 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.

Methods: 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.

Results: 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.

Conclusion: WZYD has the pharmacological effect on relieving hyperalgesia in CM model rats, possibly by affecting central and peripheral 5-HT.