Date Available

4-19-2021

Year of Publication

2019

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Medicine

Department/School/Program

Pharmacology and Nutritional Sciences

Advisor

Dr. Jia Luo

Abstract

Fetal alcohol spectrum disorders (FASD) are caused by alcohol exposure during pregnancy and is the leading cause of mental retardation. Alcohol exposure during development results in the loss of neurons in the developing brain. The underlying molecular mechanisms are unclear and there currently is no cure for FASD. Ethanol-induced neuronal death is accompanied by neuroinflammation. Chemokine monocyte chemoattractant protein 1 (MCP-1) and its receptor C-C chemokine receptor type 2 (CCR2) are critical mediators of neuroinflammation and microglial activation. Using a third trimester equivalent mouse model of ethanol exposure, we found that treatment of Bindarit (MCP-1 synthesis inhibitor) and RS504393 (CCR2 antagonist) significantly reduced ethanol-induced microglia activation/neuroinflammation, and neuroapoptosis in the developing brain. Moreover, ethanol plus MCP-1 caused more neuronal death in a neuron/microglia co-culture system than neuronal culture alone, and Bindarit and RS504393 attenuated ethanol-induced neuronal death in the co-culture system. Ethanol activated TLR4 and GSK3β, two key mediators of microglial activation in the brain and cultured microglial cells (SIM-A9). Blocking MCP-1/CCR2 signaling attenuated ethanol-induced activation of TLR4 and GSK3β.

Further, we determined whether knocking out of MCP-1/CCR2 ameliorates neonatal alcohol exposure-induced long-lasting behavioral deficits in adolescent and adult mice. C57BL/6 and MCP-1-/-/CCR2-/- mice were exposed to alcohol (5 g/kg) by subcutaneously injection on PD4. A series of behavioral tests including Open Field (PD 35-36 and PD 70-71), Rotor-Rod (PD 38 and PD 73), Balance Beam (PD 40 and PD75) and Morris Water Maze (PD 42 and PD77) were performed in the adolescence and adulthood. We found that MCP-1-/-/CCR2-/- mice were resistant to neonatal alcohol exposure-induced deficits in motor function in the Rotor-Rod and Balance Beam tests; MCP-1 and CCR2 deficiency also protected mice against neonatal ethanol exposure induced long lasting deficits in learning and memory in the Morris Water Maze testing. Collectively, these results suggest that MCP-1/CCR2 signaling plays an important role in ethanol-induced microglial activation/neuroinflammation and neurodegeneration in the developing brain and also plays an important role in developmental alcohol exposure induced long-lasting behavioral deficits in adolescence and adulthood.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2019.062

Funding Information

Grants: NIH AA017226 and AA015407

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