Elevated prodynorphin expression associated with ethanol withdrawal convulsions A.S. Beadles-Bohling a,b,c,d, *, J.C. Crabbe a,b,c,d , K.M. Wiren a,b,c,d a Portland Alcohol Research Center, Research Service P3-R&D-39, 3710 SW US Veteran's Hospital Road, Oregon Health Sciences University, Portland, OR 97201, USA b Neuroscience Program, Research Service P3-R&D-39, 3710 SW US Veteran's Hospital Road, Oregon Health Sciences University, Portland, OR 97201, USA c Department of Behavioral Neuroscience, Research Service P3-R&D-39, 3710 SW US Veteran's Hospital Road, Oregon Health Services University, Portland, OR 97201, USA d Veteran's Aairs Medical Center, Research Service P3-R&D-39, 3710 SW US Veteran's Hospital Road, Oregon Health Sciences University, Portland, OR 97201, USA Abstract The hypothesis that k-opioid system activity may in part mediate convulsions exhibited during ethanol withdrawal was tested by exposing Withdrawal Seizure-Prone (WSP) and Withdrawal Seizure-Resistant (WSR) mice to chronic ethanol. Whole brain was harvested for RNA isolation and prodynorphin mRNA steady-state levels in whole brain were examined using Northern blot analysis. The data revealed signi®cantly increased levels of prodynorphin mRNA expression in mice susceptible to ethanol withdrawal convulsions after withdrawal, with no corresponding increase in prodynorphin steady-state levels in mice resistant to ethanol withdrawal convulsions. These ®ndings were not due to basal dierences in prodynorphin expression between the WSP and WSR mice. To verify that the dierences observed were not due to an ethanol-induced global alteration in gene transcription, mRNA levels of the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase were measured. Glyceraldehyde-3-phosphate dehydrogenase expression was unchanged following both chronic exposure to ethanol and chronic exposure followed by withdrawal. These results extend our understanding of prodynorphin's role in generalized seizure activity to include ethanol withdrawal-induced convulsions. Our ®ndings suggest that prodynorphin expression is modulated during ethanol withdrawal convulsions, or alternatively, prodynorphin may mediate the severity of ethanol withdrawal convulsions. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Prodynorphin; Withdrawal; Convulsions; Ethanol; Aversion; Selected lines; k-Opioid receptors; Genetics 1. Introduction Ethanol withdrawal is a physiological response to the absence of ethanol that is exhibited after an organ- ism has become physically dependent upon alcohol. This response is believed to be a physical adaptation that the nervous system undergoes in the presence of ethanol (Himmelsbach, 1942) and is included in the National Institute on Alcohol Abuse and Alcoholism's de®nition of alcoholism. Withdrawal can be displayed in various forms, and in humans can include symp- toms such as nausea, sweating, shakiness and anxiety (Victor, 1990; Victor and Adams, 1953), (http://sil- k.nih.gov/silks/niaaa1/publication/booklet.htm). In ad- dition, estimates suggest that 4±7% of alcoholics (Hauser, 1990) suer from seizures that can be life threatening and even fatal; therefore, it is important that we understand the mechanisms underlying ethanol dependence and withdrawal. The purpose of this study Neurochemistry International 37 (2000) 463±472 0197-0186/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S0197-0186(00)00056-5 www.elsevier.com/locate/neuint * Corresponding author. Tel.: +1-503-220-8262; fax: +1-503-273- 5351. E-mail address: bohlinga@ohsu.edu (A.S. Beadles-Bohling).