Extracts of Poria cocos improve functional dyspepsia via regulating brain-gut peptides, immunity and repairing of gastrointestinal mucosa

Poria cocos (Schw.) Wolf (PC), a fungus, has been used for more than 2000 years as a food and medicine in China. It has a very good therapeutic effect for functional dyspepsia (FD). However, the material basis and mechanism of PC on FD were not reported.To investigate the function and potential mechanisms of PC including its three extracts (triterpenoid, PCT; water-soluble polysaccharide, PCWP; acidic polysaccharide, PCAP) on FD.The study explored the therapeutic effect of PC and its three extracts on FD in rats for the first time and discussed its mechanisms based on brain-gut peptides, immunity and repair of the gastrointestinal mucosa.The chemical components of PC extracts were analyzed and quantified using ultra high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS) and gel permeation chromatography coupled with size exclusion chromatography (GPC/SEC). The FD rat models were established using weight-loaded forced swimming and alternate-day fasting for 42 days. After 14 days of treatment, the effect and mechanisms were investigated using ELISA, histopathology, immunohistochemistry as well as Western blot.Seventy-seven triterpenoids in PCT were identified. PCWP was primarily composed of component A (Mw: 3.831 × 107 Da), component B (Mw: 5.650 × 106 Da) and component C (Mw: 113,117 Da). PCAP was a homogeneous composition with an average Mw of 74,320 Da. PCT, PCWP and PCAP alleviated the symptoms of FD. These extracts promoted the repair of gastrointestinal mucosa and regulated the balance between the T helper cell (Th)1/Th2 axis and the Th17/Treg axis. PCT and PCWP regulated brain-gut peptides more effectively, PCWP and PCAP enhanced immunity more effectively. Further study demonstrated that these extracts may have enhanced immunity via the Toll-like receptor (TLR) and c-Jun N-terminal kinase (JNK) signaling pathways.PC extracts showed therapeutic effects on FD rats, and the mechanism of action involved multiple pathways. PCAP, which is often discarded in traditional applications, was effective. Our study provides new ideas for the application and development of PC extracts.