Comparison of ethanol-related behaviors and FosB mapping in hybrid mice with distinct drinking patterns

textDistinct alcohol self-administration behaviors are observed when comparing two F1 hybrid strains of mice: C57BL/6J x NZB/B1NJ (B6xNZB) show reduced alcohol preference (RAP) after experience with high concentrations of alcohol and abstinence periods and C57BL/6J x FVB/NJ (B6xFVB) show sustained alcohol preference (SAP), providing models of stable, high alcohol consumption and moderate drinking. The purpose of this dissertation is to characterize ethanol-related behaviors and define neurocircuits engaged by SAP and RAP. We performed a battery of behavioral tests to define behaviors that predict SAP and RAP. B6xFVB exhibited less severe ethanol-induced conditioned taste aversion and were less sensitive to ethanol-induced loss of righting reflex (LORR) than B6xNZB. Both hybrids demonstrated ethanol-induced place preference and low ethanol withdrawal severity. Hybrids differ in sensitivity to the aversive and sedative, but not rewarding, effects of ethanol. Results of elevated plus maze, mirror chamber, and locomotor tests reveal B6xFVB mice are less anxious and more active than B6xNZB mice. The validity of the SAP behavioral phenotype in B6xFVB mice was determined by testing whether chronic self-administration of ethanol produced tolerance or dependence. We measured responses from ethanol-naïve and ethanol-experienced mice in tests of ethanol-induced hypothermia, withdrawal severity, and LORR. Chronic ethanol self-administration resulted in tolerance to sedative and hypothermic effects of ethanol; however, physical dependence was not evident as measured by ethanol withdrawal severity. We tested the hypothesis that SAP and RAP behavioral differences are represented by differential production of the inducible transcription factor, FosB. FosB immunoreactivity was quantified in 16 brain structures after chronic ethanol consumption or only water. Neuronal activity (as measured by FosB levels) depended on ethanol experience, brain region, and genotype, further supporting the notion that neuronal circuitry underlies motivational aspects of ethanol consumption. For B6xNZB mice, ethanol consumption resulted in increased neuronal activity in the EW, VTA, and amygdala, known ethanol- reward-, and stress-related brain regions. In B6xFVB, ethanol consumption resulted in a larger network of correlated regional activity, whereas in B6xNZB ethanol consumption resulted in a smaller network. These studies characterized genetic models of stable, high consumption (SAP) and moderate drinking (RAP) in two hybrid mouse strains.Institute for Neuroscienc

FUNCTIONAL IMPLICATIONS OF THE CLOCK 3111T/C SINGLE-NUCLEOTIDE POLYMORPHISM

Circadian rhythm disruptions are prominently associated with Bipolar Disorder (BD). Circadian rhythms are regulated by the molecular clock, a family of proteins that function together in a transcriptional-translational feedback loop. The CLOCK protein is a key transcription factor of this feedback loop, and previous studies have found that manipulations of the Clock gene are sufficient to produce manic-like behavior in mice (Roybal et al., 2007). The Clock 3111T/C single-nucleotide polymorphism (SNP; rs1801260) is a genetic variation of the human Clock gene that is significantly associated with increased frequency of manic episodes in BD patients (Benedetti et al., 2003). The 3111T/C SNP is located in the 3’ untranslated region of the Clock gene. In this study, we sought to examine the functional implications of the human Clock 3111T/C SNP by transfecting a mammalian cell line (mouse embryonic fibroblasts isolated from Clock -/- knockout mice) with pcDNA plasmids containing the human Clock gene with either the T or C SNP at position 3111. We then measured circadian gene expression over a 24 hour time period. We found that the Clock3111C SNP resulted in higher mRNA levels than the Clock 3111T SNP. Further, we found that Per2, a transcriptional target of CLOCK, was also more highly expressed with Clock 3111C expression, indicating the 3’UTR SNP affects the expression, function and stability of Clock mRNA