Midbrain FA initiates neuroinflammation and depression onset in both acute and chronic LPS-induced depressive model mice

In this study, we report that midbrain FA derived from lipopolysaccharide (LPS) is a direct trigger of depression. Using an acute depressive model in mice, we found that one-week intraperitoneal injection (i.p.) of LPS activated semicarbazide-sensitive amine oxidase (SSAO) leading to FA production from the midbrain vascular endothelium. In both in vitro and in vivo experiments, FA stimulated the production of cytokines such as IL-1β, IL-6, and TNF-α. Strikingly, one-week microinfusion of FA as well as LPS into the midbrain dorsal raphe nucleus (DRN, a 5-HT-nergic nucleus) induced depressive-like behaviors and concurrent neuroinflammation. Conversely, NaHSO3 (a FA scavenger), improved depressive symptoms associated with a reduction in the levels of midbrain FA and cytokines. Moreover, the chronic depressive model of mice injected with four-week i.p. LPS exhibited a marked elevation in the levels of midbrain LPS accompanied by a substantial increase in the levels of FA and cytokines. Notably, four-week i.p. injection of FA as well as LPS elicited cytokine storm in the midbrain and disrupted the blood-brain barrier (BBB) by activating microglia and reducing the expression of claudin 5 (CLDN5, a protein with tight junctions in the BBB). However, the administration of 30 nm nano-packed coenzyme-Q10 (Q10, an endogenous FA scavenger), phototherapy (PT) utilizing 630-nm red light to degrade FA, and the combination of PT and Q10, reduced FA accumulation and neuroinflammation in the ...
Source: Brain, Behavior, and Immunity - Category: Neurology Authors: Source Type: research