title: Modeling the onset of drug dependence: a consideration of the requirement for protein synthesis.
abstract: It has been proposed, with some supporting evidence, that development of opiate tolerance and dependence requires protein synthesis. However, a quantitative, biologically based model within which to analyse and support the data has been lacking. Utilizing such a framework or model, we recently compared the time course of onset of opiate dependence in laboratory animals, with the mathematical time course of general changes in protein levels. Not only did the time course of onset of dependence parallel the time course of increasing levels of a protein, but also the half-life of the putative protein required by the model was very similar to those of many brain proteins. In this study, we have more extensively tested the model by producing and examining a much more detailed and surprisingly complex time course of the onset of dependence. Applying the protein synthesis time course model to the data suggested the presence of two distinct components of dependence, an early transient component and a later long-lasting component. These components appear to correspond to acute and chronic dependence, respectively. The protein synthesis hypothesis more readily applies to the chronic dependence portion. Because consideration of the model can generate components that correspond to accepted and well-known components of dependence, both the utility of the model as well as the hypothesis that opiate dependence at least partially requires protein synthesis are supported. It is also possible that individual components of the withdrawal syndrome have individual and unique rate limiting mechanisms. In any case, time course analysis may be helpful in revealing underlying mechanisms of change.
authors.affiliation: Bioinformatics Program, University of California San Diego, La Jolla CA 92093, USA. ajoyce@ucsd.edu
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Joyce
authors.forename: Keith
authors.initials: K
authors.lastname: Easterling
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Holtzman
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kuhar
mesh_terms: D000208:Acute Disease; D000818:Animals; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D008297:Male; D008954:Models, Biological; D009270:Naloxone; D009293:Opioid-Related Disorders / Q000378:metabolism*; D014176:Protein Biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000378:metabolism
chemical_list: D009270:Naloxone