Huanglian Wendan Decoction Ameliorates Insomnia-Like Phenotypes in a Composite Mouse Model with Phlegm-Heat-Related...

Huanglian Wendan Decoction (HLWDD) is a traditional Chinese medicine formula commonly used to treat insomnia, and is particularly suitable for patients presenting with symptoms associated with phlegm-heat. However, the biological mechanisms underlying its therapeutic effects have not yet been fully elucidated.

The aim of this study is to investigate the effects of HLWDD on insomnia-like phenotypes in a composite mouse model with phlegm-heat-related features, and to explore its potential mechanisms from the perspective of the brain-gut axis.

A composite mouse model exhibiting insomnia-like phenotypes and phlegm-heat-related features was established using 4-chloro-DL-phenylalanine (PCPA) and an HF60 high-fat diet and was subsequently treated with HLWDD. General condition and behavioural changes were evaluated; gut microbiota composition was analysed using 16S rRNA sequencing; serum levels of tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were measured; serum metabolic profiles were analysed using non-targeted metabolomics; and brain levels of acetylcholine (ACh), γ-aminobutyric acid (GABA), and brain-derived neurotrophic factor (BDNF), together with proteins related to PI3K/AKT/CREB signalling, were assessed.

The model mice exhibited behavioural abnormalities, dyslipidaemia, elevated serum levels of TNF-α, IL-6 and IL-1β, colonic mucosal damage, reduced expression of tight junction proteins, and gut microbiota dysbiosis. HLWDD alleviated these abnormalities and partially restored the gut microbiota composition, including an increase in Akkermansia and a reduction in Desulfovibrio-associated taxa. Non-targeted metabolomics analysis identified three metabolites showing model-associated alterations that were reversed following HLWDD treatment, including PC 16:1_22:5, which was decreased in the model group and increased following HLWDD treatment. Concurrently, HLWDD increased the levels of acetylcholine (ACh), γ-aminobutyric acid (GABA) and brain-derived neurotrophic factor (BDNF) in the brain, and restored PI3K expression as well as the phosphorylation of AKT and CREB, with the high-dose group showing more pronounced effects.

HLWDD improved the insomnia-like phenotype in a composite mouse model, whilst simultaneously improving gut microbiota dysbiosis, impaired intestinal barrier function, systemic inflammation, lipid metabolism, and central neurotransmitter and neurotrophic factor levels. HLWDD also partially reversed the model-associated decrease in serum PC 16:1_22:5 and was accompanied by restoration of PI3K/AKT-CREB/BDNF-related signalling. These findings suggest that the action of HLWDD may involve the coordinated regulation of the gut microbiota-host metabolism-central nervous system axis, providing experimental evidence for its multi-level, multi-target effects against insomnia.