Magnetic resonance imaging and micro-computed tomography reveal brain morphological abnormalities in a mouse model of early moderate prenatal ethanol exposure.

Abstract

BACKGROUND\nThis study investigated the effects of early moderate prenatal ethanol exposure (PEE) on the brain in a mouse model that mimics a scenario in humans, whereby moderate daily drinking ceases after a woman becomes aware of her pregnancy.\n\n\nMETHODS\nC57BL/6\u202fJ pregnant mice were given 10% v/v ethanol from gestational day 0-8 in the drinking water. The male offspring were used for imaging. Anatomical and diffusion Magnetic Resonance Imaging were performed in vivo at postnatal day 28 (P28, adolescence) and P80 (adulthood). Micro-Computed Tomography was performed on fixed whole heads at P80. Tensor-based morphometry (TBM) was applied to detect alterations in brain structure and voxel-based morphometry (VBM) for skull morphology. Diffusion tensor and neurite orientation dispersion and density imaging models were used to detect microstructural changes. Neurofilament (NF) immunohistochemistry was used to validate findings by in vivo diffusion MRI.\n\n\nRESULTS\nTBM showed that PEE mice exhibited a significantly smaller third ventricle at P28 (family-wise error rate (FWE), p\u202f<\u202f.05). All other macro-structural alterations did not survive FWE corrections but when displayed with an uncorrected p\u202f<\u202f.005 showed multiple regional volume reductions and expansions, more prominently in the right hemisphere. PEE-induced gross volume changes included a bigger thalamus, hypothalamus and ventricles at P28, and bigger total brain volumes at both P28 and P80 (2-sample t-tests, uncorrected for multiple comparison). Disproportionately smaller olfactory bulbs following PEE were revealed at both time-points. No alterations in diffusion parameters were detected, but PEE animals exhibited reduced NF positive staining in the thalamus and striatum and greater bone density in various skull regions.\n\n\nCONCLUSION\nOur results show that early moderate PEE can cause alterations in the brain that are detectable during development and adulthood.