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| Drug Effects on Behavior: Animal Models |
| Saturday, May 24, 2008 |
| 4:00 PM–4:50 PM |
| Inspiration Studio |
| Area: BPH |
| Chair: Dennis J. Hand (Central Michigan University) |
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| Behavioral Effects of Cannabinoid Drugs on the Reinforcing Properties of Food in Rats. |
| Domain: Applied Research |
| ALEXA A. WAKLEY (Idaho State University), Erin B. Rasmussen (Idaho State University), Becky Lynn Hansis-O'Neill (Idaho State University) |
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| Abstract: Gestational food restriction (GFR) has been shown to cause obesity, by programming the neuroendocrine system in a manner that increases food intake. To extend the findings on GFR, we investigated how behavioral choice for food is affected by acute exposure to cannabinoid drugs, (a drug class that affects the reinforcing properties of food) in GFR offspring. Subjects included offspring of dams that were food deprived by 0% or 45% - 50% of their free-feeding intake from days 1-18 of gestation. As adults, the offspring were tested using a progressive-ratio schedule of sucrose food reinforcement. Then, injections of 2-AG (0.03-3.75mg/kg), and SR141716 (0.3-10.0mg/kg), a cannabinoid agonist and antagonist respectively, as well as scopolamine (1.0-10.0mg/kg; a negative control), were administered. Results show 2-AG dose-dependently increased breakpoints for sucrose; SR141716 dose-dependently reduced breakpoints. While scopolamine increased breakpoints as well, this was due to a motor effect that was present in a no-food delivery condition. A group difference in sensitivity to these drugs was not found, however the results from this study are the first to show behavioral effects of the endogenous cannabinoid, 2-AG, on the reinforcing properties of food. Moreover, SR141716’s effects on progressive-ratio schedules were replicated. |
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| Strain Differences in the Effects of d-Amphetamine on Impulsive Choice. |
| Domain: Applied Research |
| DENNIS J. HAND (Central Michigan University), Aaron R. Arbogast (Central Michigan University), Andrew T. Fox (Central Michigan University), Mark P. Reilly (Central Michigan University) |
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| Abstract: Attention-Deficit/Hyperactivity Disorder (ADHD) is often characterized by impulsivity, a relative intolerance to reinforcer delay, which may be inferred from choice situations that juxtapose immediate and delayed reinforcers. A rodent model of ADHD, the Spontaneously Hypertensive Rat (SHR), has been shown to be useful in that rats from the strain prefer smaller, immediate reinforcers over larger, delayed ones. The present study attempts to pharmacologically validate the SHR model of ADHD by examining the effects of d-amphetamine (Dexedrine®), a psychomotor stimulant commonly prescribed for ADHD, on impulsivity. d-Amphetamine was predicted to increase self-control in SHRs and have no effect on choice in their progenitor strain, Wistar Kyoto (WKY). All rats made choices between one food pellet delivered immediately (impulsive choice) or three pellets after a delay of 0, 3 and 12 seconds (self-control choice). d-Amphetamine had no systematic effect on choice for the SHRs under any dose or delay, however it dose-dependently increased choices for the small/immediate reinforcer, increased response latency and decreased the number of choices made at the 12-s delay for the WKYs. Implications for pharmacotherapuetic interventions and the SHR model of ADHD will be discussed. |
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