INTEGRATIVE NEUROSCIENCE INITIATIVE ON ALCOHOLISM (INIA)

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Aims: Use in vivo quantitative neuroimaging of alcohol-preferring rat (P-rat), an animal model of alcoholism, to examine longitudinal effects of alcohol exposure, while controlling for morphological changes that occur with age. Methods: Structural MRI was acquired in a longitudinal design on two cohorts of adult P-rats. Some of each cohort were never exposed to alcohol, while others received alcohol: a three-bottle choice with 0%, 15% (or 20%), and 30 % (or 40%) several different exposure schemes: continuous exposure; cycles of 2 weeks on followed by 2 weeks off alcohol; and binge drinking in the dark leading to high levels of alcohol consumption. Scanning was repeated when rats were approximately 3, 6, 10, 13, 15, and 19 months. Results: The non-alcohol exposed rats showed growth in whole brain volume that reached maximal levels by about 15 months, whereas body weight continued its gain without asymptote. Growth was not uniform across brain structures measured. Over the initial 12 months of the study, corpus callosum area expanded 36%, cerebellum 17%, and hippocampus 10%; although the ventricles enlarged 21%, the effect was not significant because of substantial between-subject variance. Factors affecting growth rate estimates included litter effects, MR image signal-to-noise ratio, and measurement error. Unlike longitudinal human reports of regional volume declines in aging brain tissue, several brain structures in adult rats continued growing. The alcohol-exposed rats also showed brain growth but this was attenuated, particularly in the corpus callosum.