Effects of ethanol on immune response in the brain: region-specific changes in adolescent versus adult mice - PubMed (original) (raw)

Effects of ethanol on immune response in the brain: region-specific changes in adolescent versus adult mice

Cynthia J M Kane et al. Alcohol Clin Exp Res. 2014 Feb.

Abstract

Background: Alcohol use occurs across the life span beginning in adolescence and continuing through adulthood. Ethanol (EtOH)-induced pathology varies with age and includes changes in neurogenesis, neurodegeneration, and glial cell activation. EtOH-induced changes in glial activation and immune activity are believed to contribute to EtOH-induced neuropathology. Recent studies indicate an emerging role of glial-derived neuroimmune molecules in alcohol abuse and addiction.

Methods: Adolescent and adult C57BL/6 mice were treated via gavage with 6 g/kg EtOH for 10 days, and tissue was harvested 1 day post treatment. We compared the effects of EtOH on chemokine and cytokine expression and astrocyte glial fibrillary acidic protein (GFAP) immunostaining and morphology in the hippocampus, cerebellum, and cerebral cortex.

Results: EtOH increased mRNA levels of the chemokine CCL2/MCP-1 in all 3 regions of adult mice relative to controls. The cytokine interleukin-6 (IL-6) was selectively increased only in the adult cerebellum. EtOH did not affect mRNA levels of the cytokine tumor necrosis factor-alpha (TNF-α) in any of these brain regions in adult animals. Interestingly, CCL2, IL-6, and TNF-α mRNA levels were not increased in the hippocampus, cerebellum, or cortex of adolescent mice. EtOH treatment of adult and adolescent mice resulted in increased GFAP immunostaining.

Conclusions: Collectively, these data indicate an age- and region-specific susceptibility to EtOH regulation of neuroinflammatory and addiction-related molecules as well as astrocyte phenotype. These studies may have important implications concerning differential alcohol-induced neuropathology and alcohol addiction across the life span.

Keywords: Adolescent; Adult; Astrocyte; CCL2; Neuroinflammation.

PubMed Disclaimer

Figures

Figure 1

Effect of ethanol on CCL2, IL-6, and TNF-α expression in adult and adolescent mouse hippocampus. Animals were given 6.0 g/kg/day ethanol split into two doses and administered 7 h apart. Ethanol was administered for 10 days and mice were sacrificed 24h after the final dose of ethanol. Water was administered to vehicle mice. The hippocampus was isolated, RNA prepared, cDNA synthesized, and mRNA levels were determined by real-time quantitative RT-PCR. Results are expressed as fold changes relative to vehicle treated mice, and all values are normalized against β-actin. Values are mean +/− SEM from 10 vehicle and 13 ethanol treated adult mice (A) or from 8 vehicle and 6 ethanol treated adolescent mice (B). Duplicate PCR reactions were performed on each sample. Open bars represent vehicle-treated mice. Solid bars represent ethanol-treated mice. ***, P<0.001 versus vehicle treated mice.

Figure 2

Effect of ethanol on CCL2, IL-6, and TNF-α expression in adult and adolescent mouse cerebellum. Animals were treated and samples analyzed as described in Figure 1. Adult animals (A). Adolescent animals (B). Open bars represent vehicle-treated animals. Solid bars represent ethanol-treated animals. Results are expressed as fold changes relative to vehicle treated mice, and all values are normalized against β-actin. Values are mean +/− SEM from 10 vehicle and 13 ethanol treated adult mice (A) or from 8 vehicle and 6 ethanol treated adolescent mice (B). Duplicate PCR reactions were performed on each sample. **, P<0.01, versus vehicle treated mice.

Figure 3

Effect of ethanol on CCL2, IL-6, and TNF-α expression in adult and adolescent mouse cerebral cortex. Animals were treated and samples analyzed as described in Figure 1. Adult animals (A). Adolescent animals (B). Open bars represent vehicle-treated animals. Solid bars represent ethanol-treated animals. Results are expressed as fold changes relative to vehicle treated mice, and all values are normalized against β-actin. Values are mean +/− SEM from 10 vehicle and 13 ethanol treated adult mice (A) or from 8 vehicle and 6 ethanol treated adolescent mice (B). Duplicate PCR reactions were performed on each sample. *, P<0.05, versus vehicle treated mice.

Figure 4

Effect of ethanol on GFAP immunostaining and astrocyte morphology in adult and adolescent mice. Photomicrographs illustrate the appearance of GFAP stained astrocytes in vehicle (A-C, G-I) and ethanol (D-F, J-L) treated adult (A-F) and adolescent (G-L) mice. Arrowheads denote ethanol induced increases in GFAP staining of astrocytes associated with larger vascular elements. Inset: astrocytes in the hippocampal CA1 region. Animals were treated as described in Figure 1. Scale bars in A represent 200 um and 100 um (inset) and apply to all hippocampal images. Scale bar in B represents 100 um in B and E and 50 um in H and K and all cerebral cortex images. Hippocampus (HIP), hippocampal field CA1 (CA1), hippocampal field CA3 (CA3), dentate gyrus (DG), cerebellum (CBL), cerebral cortex (CTX).

References

1. Achur RN, Freeman WM, Vrana KE. Circulating cytokines as biomarkers of alcohol abuse and alcoholism. J Neuroimmune Pharmacol. 2010;5:83–91. - PMC - PubMed
1. Alaux-Cantin S, Warnault V, Legastelois R, Botia B, Pierrefiche O, Vilpoux C, Naassila M. Alcohol intoxications during adolescence increase motivation for alcohol in adult rats and induce neuroadaptations in the nucleus accumbens. Neuropharmacology. 2012;67C:521–531. - PubMed
1. Alfonso-Loeches S, Guerri C. Molecular and behavioral aspects of the actions of alcohol on the adult and developing brain. Crit Rev Clin Lab Sci. 2011;48:19–47. - PubMed
1. Alfonso-Loeches S, Pascual-Lucas M, Blanco AM, Sanchez-Vera I, Guerri C. Pivotal role of TLR4 receptors in alcohol-induced neuroinflammation and brain damage. J Neurosci. 2010;30:8285–8295. - PMC - PubMed
1. Blanco AM, Guerri C. Ethanol intake enhances inflammatory mediators in brain: role of glial cells and TLR4/IL-1RI receptors. Front Biosci. 2007;12:2616–2630. - PubMed

Effects of ethanol on immune response in the brain: region-specific changes in adolescent versus adult mice - PubMed (original) (raw)