ACOUSTIC STARTLE AND COCAINE USE IN RATS Open Access

Wheeler, Marina Georgia (2011)

Permanent URL: https://etd.library.emory.edu/concern/etds/9k41zd701?locale=en
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Abstract

Abstract
ACOUSTIC STARTLE AND COCAINE USE IN RATS
Cocaine addiction is the compulsive use of cocaine despite the negative consequences of doing so and a desire to abstain. Identifying individual factors that can predict vulnerability to abuse cocaine is an important aim of scientific investigation and can be used to develop early interventions directed towards at risk populations as well as for the development of animal models which more appropriately reflect the disorder. Interestingly, men addicted to cocaine but no longer using cocaine exhibit markedly diminished acoustic startle amplitudes. These decreased startle amplitudes could precede or be a consequence of cocaine use however the evidence available does not suggest that they are the consequence. There is no evidence for or against the alternative, that low acoustic startle precedes cocaine use. This dissertation project investigates the potential value of acoustic startle amplitudes in predicting vulnerability to abuse cocaine using a rat intravenous model of cocaine self-administration. Results show that rats with drug naïve low startle amplitudes are more sensitive to cocaine, motivated, persistent in cocaine seeking and more likely to reinstate extinguished cocaine seeking compared to high startle rats. Low startle rats also exhibit a significant preference for novel environments, a behavioral phenotype previously shown to predict habitual cocaine self-administration in rats. These data suggest that low startle may precede cocaine abuse and therefore predict the likelihood to abuse cocaine.

ACOUSTIC STARTLE AND COCAINE USE IN RATS
By
Marina Georgia Wheeler
B.S. Georgia State University, 2005
M.A. Emory University, 2009
Advisor: Michael Davis, Ph.D.
A dissertation submitted to the Faculty of the
James T. Laney School of Graduate Studies of Emory University
in partial fulfillment of the requirements for the degree of
Doctor of Philosophy
in Psychology
2011

Table of Contents

Table of Contents
Table of Contents...i
List of Figures...ii
Chapter 1: General Introduction...1
Chapter 2: Sensitivity to Cocaine...17
Chapter 3: Motivation and Reinstatement...39
Chapter 4: Acoustic Startle, Novelty Preference and Persistence in Cocaine Seeking...61
Chapter 5: General Discussion...79
Supplement A: Acoustic Startle Amplitudes Pre- and Post-Cocaine Self-Administration...90


List of Figures
Baseline acoustic startle amplitudes in high and low startle: Sensitivity to cocaine...35
Acquisition of operant responding...36
Dose Response Curve...37
Percent change in responses on the active versus inactive lever...38
Baseline acoustic startle in high and low startle: Motivation to obtain cocaine...57
Acquisition of operant responding...58
Progressive ratio schedule...59
Drug and cue reinstatement of cocaine seeking...60
Acoustic startle in low and high startle rats: Novelty Preference...75
Novelty preference...76
Acoustic startle in low and high startle rats: Cocaine Seeking...77
Persistence in cocaine seeking...78
Acoustic startle in low and high startle rats: Amphetamine Challenge...112
Amphetamine potentiated acoustic startle amplitudes pre- and post-cocaine self-administration...113
Amphetamine potentiated % change in startle amplitudes...114

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