Travis J. Worst

Transcriptome analysis of frontal cortex in alcohol-preferring and nonpreferring rats

Although it is widely accepted that alcohol abuse and alcoholism have a significant genetic component of risk, the identities of the genes themselves remain obscure. To illuminate such potential genetic contributions, DNA macroarrays were used to probe for differences in normative cortical gene expression between rat strains genetically selected for alcohol self‐administration preference, AA (Alko, alcohol) and P (Indiana, preferring), or avoidance, ANA (Alko, nonalcohol) and NP (Indiana, nonpreferring). Among 1,176 genes studied, six demonstrated confirmable, differential expression following comparison of ethanol‐naive AA and ANA rats. Specifically, the mRNA level for metabotropic glutamate receptor 3 (mGluR3) was down‐regulated in the AA vs. ANA lines. In contrast, calcium channel subunit α2δ1 (cacna2d1), vesicle‐associated membrane protein 2 (VAMP2), syntaxin 1 (both syntaxin 1a and 1b; STX1a and STX1b), and syntaxin binding protein (MUNC‐18) mRNAs were found to be increased in frontal cortex following comparison of AA with ANA animals. Bioinformatic analysis of these molecular targets showed that mGluR3 and cacna2d1 fall within chromosomal locations reported to be alcohol‐related by the Collaborative Study on the Genetics of Alcoholism (COGA) as well as quantitative trait loci (QTL) studies. To determine further whether these differences were strain specific, the above‐mentioned genes were compared in ethanol‐preferring (P) and ‐nonpreferring (NP) selected lines. VAMP2 was the only gene that displayed statistically different mRNA levels in a comparison of P and NP rats. In conclusion, the altered cortical gene expression illuminated here would have the effect of altering neurotransmitter release in AA rats (compared with ANA rats). Such alterations, however, might not be a universal characteristic of all animal models of alcohol abuse and will also require further investigation in post‐mortem human samples.

The Future of Proteomics in the Study of Alcoholism

This article represents the proceedings of a workshop at the 2003 annual meeting of the Research Society on Alcoholism in Fort Lauderdale, FL. The workshop organizers/chairpersons were Chinnaswamy Kasinathan and Paul Manowitz. The presentations were (1) Introduction to the field of proteomics, by Kent Vrana; (2) Use of proteomics in the identification of urinary biomarkers for alcohol intake, by Chinnaswamy Kasinathan, Paul Thomas, and Paul Manowitz; (3) Proteomics screening illuminates ethanol-mediated induction of HDL proteins in macaques, by Kent Vrana, Randy Gooch, Travis Worst, Stephen Walker, Aaron Xu, Peter Pierre, Heather Green, and Kathleen Grant; and (4) Proteomics applied to the study of the liver, by Laura Beretta.

Trigeminal Neuronal Recording in Animal Models of Orofacial Pain

The electrical signal associated with nerve cells, mainly as a result of changes in the membrane potential during functional activity, can be recorded extracellularly to study central mechanisms underlying sensory processing. The secondary neurons in the spinal trigeminal complex receive inputs from peripheral neurons that innervate the orofacial region and forward information to the higher levels of the nervous system. Analyzing activity patterns of trigeminal neurons related to pain perception has proven to be an efficient method in studying orofacial pain mechanisms. Here we describe some basic techniques and tips for extracellular single neuron recording from the subnucleus caudalis of the trigeminal spinal nucleus in rats with orofacial injury. Two different rat models with temporomandibular joint inflammation and inferior alveolar nerve transection are described.

118 – cDNA Arrays in Alcohol-Related Pathology: Methods and Approaches

This chapter reviews aspects of technologies and experimental design in transcriptomics. To better understand alcohol abuse and alcoholism, two key genetic elements prove to be important, these concepts suggest that: (1) genetic predispositions can place an individual at a risk for abuse and addiction. (2) There are genomic responses to chronic alcohol administration that contribute to clinical issues of tolerance, dependence (physical and psychological), and withdrawal. Aspects of both of these issues can involve altered levels of the messenger ribonucleic acid. That is, two individuals might express different levels of the same gene, thus placing one at a unique risk for developing alcoholism. Alternatively, chronic ethanol exposure will itself engender changes in the normal patterns of gene expression and create a new physiological state. The efficient, high screening of differences in the gene expression is the purview of the DNA array and constitutes the central technological feature of the new field of transcriptomics. This technology, while powerful, requires significant attention to detail, and considerable technical expertise.