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Individual differences in delay discounting and nicotine self-administration in rats

Sweitzer, Maggie M. (2009) Individual differences in delay discounting and nicotine self-administration in rats. Master's Thesis, University of Pittsburgh. (Unpublished)

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Delay discounting—a behavioral measure of impulsivity defined as a tendency to prefer a small, immediate reward over a larger reward delayed in time—has been extensively linked with tobacco smoking. However, the causal direction of this relationship remains unclear. One possibility is that delay discounting may be a marker for an underlying vulnerability to nicotine reinforcement—a possibility which can be isolated using an animal model. In the current study, we investigated whether indifference points derived using an adjustable delay procedure of delay discounting predicted several indices of nicotine reinforcement in rats, including rate of acquisition of nicotine self-administration, break point reached on a progressive ratio schedule of reinforcement, or a shift in the dose-response curve. Stable indifference points were assessed for 63 male Sprague-Dawley rats, and extreme groups of highly impulsive (HI; n=15) and low impulsive (LI; n=11) rats were selected to self-administer nicotine. Rats responded by nose poking for infusions of 0.03 mg/kg nicotine during 1 hour daily sessions. After a 20 session acquisition period, rats completed 3 4-hour progressive ratio sessions, during which the response requirement was increased after each infusion earned. This was followed by 3 1-hour fixed ratio sessions at each of 3 nicotine doses, presented in ascending order (0.015, 0.03, and 0.09 mg/kg). All but one rat (HI group) acquired stable nicotine self-administration; however, no group differences in rate of acquisition were observed. HI and LI rats did not differ in their responses on a progressive ratio schedule or infusions earned at any dose of nicotine, although a significant dose-response effect was observed overall. Indifference points reassessed after self-administration were highly correlated with original indifference points, and mean indifference points for each group at the second assessment did not differ significantly from baseline assessment. These results suggest that delay discounting is a highly reliable measure, but may not be a predictive marker for increased vulnerability to nicotine self-administration in rats.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Sweitzer, Maggie M.mms74@pitt.eduMMS74
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairDonny, Eric Cedonny@pitt.eduEDONNY
Committee MemberCaggiula, Anthonytonypsy@pitt.eduTONYPSY
Committee MemberManuck, Stephenmanuck@pitt.eduMANUCK
Date: 22 January 2009
Date Type: Completion
Defense Date: 23 June 2008
Approval Date: 22 January 2009
Submission Date: 12 December 2008
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Psychology
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: smoking impulsivity
Other ID:, etd-12122008-124829
Date Deposited: 10 Nov 2011 20:10
Last Modified: 15 Nov 2016 13:54


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