Levin, Melissa
(2013)
Differentiating the primary reinforcing and reinforcement-enhancing effects of varenicline in a 2-lever, rat self-administration paradigm.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Nicotine (NIC) has two reinforcement-related effects that may contribute to dependence: 1) NIC acts as a primary reinforcer, and 2) NIC, non-associatively, enhances reinforcement from concur- rently available nonpharmacological stimuli. Varenicline (VAR), a partial agonist at nicotinic re- ceptors, is one of the most effective smoking cessation pharmacotherapies. Previous findings from our laboratory show that VAR mimics the reinforcement-enhancing effects of NIC. The present study sought to determine the role of these effects in a self-administration paradigm, in which rats were able to lever press for intravenous VAR and/or a moderately reinforcing visual stimulus (VS). For five groups of rats (i.e., the 2-lever groups), responding on one lever was reinforced with VAR (0.01, 0.06 or 0.1 mg/kg/infusion), NIC (0.06 mg/kg/infusion) or saline (SAL), while responding on a separate lever was reinforced with the VS. Three additional groups were reinforced for pressing a single, active lever and received contingent VAR paired with the VS, the VS only (while receiving noncontingent [i.e., yoked] VAR) or VAR only (all doses 0.1 mg/kg/infusion). Responding was maintained on an FR1 for five sessions, an FR2 for six sessions and an FR5 for fifteen sessions. Compared to responding for the VS in the 2-lever SAL group, responding on the active lever was significantly higher in the contingent VAR + VS group but was not significantly higher in the noncontingent VAR + VS group. Responding for VAR only was not significantly different than responding for SAL only in the 2-lever SAL group. Across the 2-lever VAR groups, responding for the VS did not significantly differ from responding for the VS in the 2-lever SAL group. Cer- tain findings of this study support the notion that VAR has reinforcement-enhancing properties, in that the contingent VAR + VS group demonstrated a significant increase in responding for the VS, compared to saline controls. Although the noncontingent VAR + VS group failed to reach significance, active-lever responding levels were elevated. Furthermore, VAR did not demonstrate primary reinforcing properties. Interestingly, it could be that rats did not respond sufficiently for VAR in the 2-lever groups to engender a reinforcement-enhancement effect.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
30 June 2013 |
| Date Type: |
Publication |
| Defense Date: |
29 June 2011 |
| Approval Date: |
30 June 2013 |
| Submission Date: |
17 April 2013 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
30 |
| 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: |
Varenicline, Nicotine, Rats, Self-Administration |
| Date Deposited: |
30 Jun 2013 17:21 |
| Last Modified: |
15 Nov 2016 14:11 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/18462 |
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