Zhen-wu-tang alleviates nephrotic syndrome by upregulating 5-HTR1B to activate AMPK/PGC-1α-mediated mitochondrial biogenesis.

ETHNOPHARMACOLOGICAL RELEVANCE: Zhen-wu-tang (ZWT) as a classic herbal formula is widely recognized for its therapeutic efficacy in treating nephropathy. It is commonly used to alleviate edema, improve renal function, and manage symptoms associated with kidney yang deficiency. However, its therapeutic efficacy and mechanism for nephrotic syndrome (NS) is not yet clear.

AIM OF THE STUDY: To investigate the underlying mechanism of ZWT in regulating mitochondrial biogenesis (MB) to treat NS.

METHODS: An adriamycin (ADR)-induced NS animal model and a renal tubular epithelial cell injury model were used, followed by intervention with three concentrations of ZWT. The location of 5-HTR1B in kidney cells was observed using immunofluorescence co-localization. Protein levels of the MB-related proteins, including recombinant transcription factor A (TFAM), peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), adenosine 5'-monophosphate-activated protein kinase (AMPK) and p-AMPK, were determined by western blotting after administration of 5-hydroxytryptamine receptor 1B (5-HTR1B) agonist and inhibitor interventions. The bioactive compounds of ZWT-containing serum were determined using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry.

RESULTS: ZWT treatment ameliorated renal dysfunction and pathological damage in NS rats by attenuating podocyte and tubular cell damage. Additionally, ZWT reduced NS-induced mitochondrial dysfunction and reactive oxygen species levels. Immunofluorescence revealed that 5-HTR1B was predominantly expressed in the collecting ducts and proximal tubule cells. In ADR-induced models, ZWT upregulated the levels of PGC-1α, TFAM, AMPK and p-AMPK proteins involved in MB. In addition, a novel finding was that both gene and protein levels of 5-HTR1B were downregulated in these injury models, whereas ZWT intervention upregulated them. Studies on 5-HTR1B agonists and antagonists indicated that ZWT regulates AMPK/PGC-1α through 5-HTR1B-mediated mechanisms. Furthermore, 24 bioactive compounds were identified in ZWT-containing serum, of which paeoniflorin bound best to 5-HTR1B and acted similarly to 5-HTR1B agonists.

CONCLUSION: Overall, this study demonstrated that ZWT alleviates NS by upregulating MB via the 5-HTR1B/AMPK/PGC-1α signaling. This novel mechanism enriches the reference of ZWT for NS therapy.