Postnatal exposure to lipopolysaccharide combined with high-fat diet consumption induces immune tolerance without prevention in spatial working memory impairment

Abstract

High-fat diet (HFD) consumption has been related to metabolic alterations, such as obesity and cardiovascular problems, and has pronounced effects on brain plasticity and memory impairment. HFD exposure has a pro-inflammatory effect associated with microglial cell modifications in the hippocampus, a region involved in the working memory process. Immune tolerance can protect from inflammation in periphery induced by HFD consumption, when the immune response is desensitized in development period with lipopolysaccharide (LPS) exposure, maybe this previously state can change the course of the diseases associated to HFDs but is not known if can protect the hippocampus's inflammatory response. In the present study, male mice were injected with LPS (100 μg.kg-1 body weight) on postnatal day 3 and fed with HFD for 16 weeks after weaning. Ours results indicated that postnatal exposure to LPS in the early postnatal developmental stage combined with HFD consumption prevented glycemia, insulin, HOMA-IR, microglial process, and increased pro-inflammatory cytokines mRNA expression, without changes in body weight gain and spatial working memory with respect vehicle + HFD group. These findings suggest that HFD consumption after postnatal LPS exposure induces hippocampal immune tolerance, without prevention in spatial working memory impairment on male mice.

Keywords: Cytokines; High-fat diet; Hippocampus; Innate immune memory; Lipopolysaccharide; Microglia; Tolerance; Working memory.