Antidepressant effects of Peiyuan Jieyu formula in a mouse model of chronic stress in conjunction with lipopolysaccharide-induced depression

Abstract

Objective: To explore the mechanism of the Peiyuan Jieyu formula in treating depression by assessing its impact on a lipopolysaccharide-induced (LPS-induced) depression mouse model. Methods: We created a mouse model of depression by exposing mice that had previously received chronic stress to intraperitoneal LPS injections. The mice were divided into the following groups: control, model, fluoxetine, Tiansi Yin, Sini powder, and low-, medium-, and high-dose Peiyuan Jieyu formula groups. Forced swim and tail suspension tests were used to assess the efficacy of the depression (despair) model, and weight gain rates were also measured. Furthermore, serum levels of various depression and inflammation-associated molecules, including tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), tryptophan, 5-hydroxytryptamine, kynurenine (KYN), and kynurenic acid (KA) were assessed. Furthermore, the expression levels of ionic calcium-binding adaptor molecule-1 (IBA-1) and indoleamine 2,3-dioxygenase (IDO) mRNA in hippocampal microglia were measured. Results: The model group displayed greater despair-associated immobility, which was shortened in response to various doses of Peiyuan Jieyu formula. Furthermore, formula administration significantly reduced serum TNF-α levels and hippocampal IDO mRNA expression. The high formula dose also reduced IFN-γ and IBA-1 levels, the latter was also decreased in response to the medium formula dose. However, the low formula dose reduced serum KYN level and KYN/tryptophan (TRP) and KYN/KA ratios. Conclusion: The Peiyuan Jieyu formula holds immense potential in treating depression in a mouse model, potentially inhibiting inflammation and improving TRP-KYN metabolic disorders.

Keywords

• Peiyuan Jieyu formula
• Depression
• Chronic stress
• Lipopolysaccharide
• Inflammation
• Tryptophan pathway