Metabolic function in patients with bipolar depression receiving anti-inflammatory agents: Findings from the MINDCARE study, a multicentre, randomised controlled trial

A Cooperative Strategy of Hippocampus Lipidomics and Anti-Inflammatory Analysis to Evaluate the Antidepressant Effect of Zhi-Zi-Chi Decoction on CUMS Mice

In this study, Balb/c mice were subjected to chronic unpredictable mild stress (CUMS) and treated with Zhi-zi-chi Decoction (ZZCD). Using a hippocampal lipidomics approach that combined ultra performance liquid chromatography (UPLC)-Q-Exactive Orbitrap MS with multivariate statistical techniques and targeted metabolic pathway analysis, we identified potential lipid metabolites and pathways associated with depression. Meanwhile, anti-inflammatory analyses were conducted in the hippocampus of mice. The chromatograms revealed that most lipids of the same class eluted within the same time period. In the scatter plot, the control and CUMS groups were obviously separated, whereas the ZZCD-treated or fluoxetine-treated groups were positioned between them. In positive and negative ion modes, a comprehensive screening identified 130 differential lipid metabolites, which were classified into 5 groups and 17 types. ZZCD was hypothesized to have a certain call-back efficiency for some differential lipid metabolites. The study identified three target metabolic pathways with certain influence values: glycerophosphate metabolism, linoleic acid metabolism, and α-linolenic acid metabolism. Although ZZCD's inhibitory effect on IL-6 was not significant, it demonstrated good therapeutic effects in reducing central system inflammation associated with IL-1β and TNF-α. The research suggested that the pathogenesis of depression might be closely related to lipid metabolism. ZZCD exhibited antidepressant effects by regulating endogenous lipid metabolism in CUMS mice.

Microglia Loss and Astrocyte Activation Cause Dynamic Changes in Hippocampal [18F]DPA-714 Uptake in Mouse Models of Depression

Major depression is a serious and chronic mental illness. However, its etiology is poorly understood. Although glial cells have been increasingly implicated in the pathogenesis of depression, the specific role of microglia and astrocytes in stress-induced depression remains unclear. Translocator protein (TSPO) has long been considered a marker of neuroinflammation and microglial activation. However, this protein is also present on astrocytes. Thus, it is necessary to explore the relationships between TSPO, microglia, and astrocytes in the context of depression. In this study, C57BL/6J male mice were subjected to chronic unpredictable stress (CUS) for 5 weeks. Subsequently, sucrose preference and tail suspension tests (TSTs) were performed to assess anhedonia and despair in these mice. [18F]DPA-714 positron emission tomography (PET) was adopted to dynamically assess the changes in glial cells before and 2, 4, or 5 weeks after CUS exposure. The numbers of TSPO+ cells, ionized calcium-binding adaptor molecule (Iba)-1+ microglial cells, TSPO+/Iba-1+ cells, glial fibrillary acidic protein (GFAP)+ astrocytes, TSPO+/GFAP+ cells, and TUNEL-stained microglia were quantified using immunofluorescence staining. Real-time PCR was used to evaluate interleukin (IL)-1β, IL-4, and IL-18 expression in the hippocampus. We observed that hippocampal [18F]DPA-714 uptake significantly increased after 2 weeks of CUS. However, the signal significantly decreased after 5 weeks of CUS. CUS significantly reduced the number of Iba-1+, TSPO+, and TSPO+/Iba-1+ cells in the hippocampus, especially in the CA1 and dentate gyrus (DG) subregions. However, this intervention increased the number of GFAP+ astrocytes in the CA2/CA3 subregions of the hippocampus. In addition, microglial apoptosis in the early stage of CUS appeared to be involved in microglia loss. Further, the expression of pro-inflammatory cytokines (IL-1β and IL-18) was significantly decreased after CUS. In contrast, the expression of the anti-inflammatory cytokine IL-4 was significantly increased after 2 weeks of CUS. These results suggested that the CUS-induced dynamic changes in hippocampal [18F]DPA-714 uptake and several cytokines may be due to combined microglial and astrocyte action. These findings provide a theoretical reference for the future clinical applications of TSPO PET.