ObjectiveTo investigate the effects of Yueju Wan on the 5-hydroxytryptamine （5-HT） signaling pathway in rats with functional dyspepsia （FD） and to explore its therapeutic mechanism in the treatment of FD. MethodsSixty Sprague-Dawley （SD） rats were randomly divided into a normal group， model group， mosapride group （1.575 mg·kg^-1）， and Yueju Wan low-， medium-， and high-dose groups （0.735， 1.47， and 2.94 g·kg^-1， respectively）. The FD rat model was established using GUO's tail-clamping stimulation combined with irregular feeding. After 14 days of modeling， rats were administered the corresponding drugs by gavage for 28 days. After treatment， gastric emptying rate and small intestinal propulsion rate were measured. Serum levels of 5-HT， tryptophan hydroxylase （TPH）， and substance P （SP） were detected by enzyme-linked immunosorbent assay （ELISA）， and acetylcholine （ACh） levels were determined by chemical methods. Histopathological changes in the gastric antrum were observed using hematoxylin-eosin （HE） staining. Real-time quantitative polymerase chain reaction （Real-time PCR） and Western blot were used to assess the mRNA and protein expression levels of 5-hydroxytryptamine 4 receptor （5-HT4R）， SP， and acetylcholinesterase （AChE） in colon tissue， as well as 5-hydroxytryptamine 3 receptor （5-HT3R）， SP， and AChE in hypothalamic tissue. Immunohistochemistry （IHC） was used to examine the expression of 5-HT and 5-HT4R in the colon and 5-HT and 5-HT3R in the hypothalamus. ResultsCompared with the normal group， the gastric emptying rate and small intestinal propulsion rate in the model group were significantly decreased （P<0.01）. Serum levels of 5-HT， SP， ACh， and TPH were significantly reduced （P<0.01）. Histopathological examination revealed irregular arrangement of glands in the gastric antrum， slight mucosal atrophy， and mild inflammatory cell infiltration. The mRNA and protein expression levels of 5-HT4R， SP， and AChE in colon tissue， as well as 5-HT3R， SP， and AChE in hypothalamic tissue， were significantly decreased （P<0.01）， and 5-HT protein expression in both the colon and hypothalamus was also significantly reduced （P<0.01）. Compared with the model group， all Yueju Wan groups showed significantly increased gastric emptying rate and small intestinal propulsion rate （P<0.01）. The glands in the gastric antrum were more regularly arranged， with no inflammatory cell infiltration observed. Serum levels of 5-HT， SP， ACh， and TPH were significantly increased （P<0.01）. The mRNA and protein expression levels of 5-HT4R， SP， and AChE in colon tissue and 5-HT3R， SP， and AChE in hypothalamic tissue were significantly upregulated （P<0.05， P<0.01）， and 5-HT protein expression in both the colon and hypothalamus was significantly increased （P<0.01）. ConclusionYueju Wan has preventive and therapeutic effects on FD， and its mechanism may be related to regulation of the 5-HT signaling pathway， promotion of brain-gut peptide secretion， and enhancement of gastric motility.