Effects of Acute and Chronic Nicotine Administration on Choice of Probabilistic Outcomes

Effects of Acute and Chronic Nicotine Administration on Choice of Probabilistic Outcomes Katya Nolder Risky choice can be operationally defined as the choice for a larger, uncertain reinforcer over a smaller, certain reinforcer. Research suggests smokers engage in more risky or maladaptive decisions when compared to nonsmokers. The relation between nicotine and risky choice could benefit from further investigation, since nicotine is the active substance of tobacco products that maintains tobacco addiction. Acute nicotine administration has shown to alter risky choice; however, since the everyday smoker uses nicotine repeatedly, more research on chronic administration is warranted and would allow for assessment of tolerance or sensitization of these effects. The present study investigated effects of acute and chronic nicotine administration on risky decision-making in Sprague-Dawley rats using a probability-discounting procedure. The probability-discounting procedure included discrete-trial choices between a small, certain reinforcer and a larger, uncertain reinforcer. The probability of larger-reinforcer delivery systematically decreased across blocks with each session. At baseline, larger-reinforcer choice systematically declined as a function of decreasing probabilities of delivery, indicating that choice was sensitive to the programmed contingencies of the procedure. Acute nicotine administration dose-dependently increased risky choice. Tolerance to nicotine’s effects on larger-reinforcer choice was observed after repeated 1.0 mg/kg nicotine administration. The results of the present study add to the existing literature that acute nicotine administration increases risky choice and demonstrate that tolerance to this effect develops after chronic exposure to the drug. Possible mechanisms behind this effect are discussed, as are suggestions for future research on nicotine and risky choice. NICOTINE AND CHOICE OF PROBABILISTIC OUTCOMES iii ACKNOWLEDGEMENTS I would like to thank Dr. Karen G. Anderson, Dr. Kathryn Kestner, and Dr. Melissa Blank for serving on my thesis committee and offering their valuable feedback and guidance throughout every stage of this project. I want to specifically thank my advisor, Dr. Karen G. Anderson, for her mentorship, endless support, and encouragement. I am lucky to work with and learn from such an accomplished and hardworking mentor. I would like to thank my past and current lab-mates, Jenny Ozga, Matt Eckard, Devin Galdieri, Rebecca Caughron-Chalmé, Paige Currie, and Erin Wylie, who helped me develop this project, collect data, and listened to and provided feedback on various iterations of my research presentations. Thank you to the West Virginia University Department of Psychology for funding this project. Thank you to all of my extended family and friends, near and far, who have continued to encourage and inspire me. I would like to extend a very special thank you to my parents, Mark and Laura Nolder, and siblings, Alex Harris, Becca Nolder, Maddie Nolder, and Nick Nolder, for their endless love and support. Lastly, I would like to thank my wonderful boyfriend, Abraham Loscher, for keeping me sane, motivating me to keep going, and supporting me every step of the way. NICOTINE AND CHOICE OF PROBABILISTIC OUTCOMES iv TABLE OF CONTENTS Page Title Page . i Abstract . ii Acknowledgements . iii Table of