Corn oil, but not cocaine, is a more effective reinforcer in obese than in lean Zucker rats.
Obesity is associated with abnormal brain reactivity in response to palatable food consumption, a factor that may contribute to non-homeostatic eating. However, little is known about how obesity interacts with the reinforcing effects of highly palatable constituents of food (e.g., fat), and if altered reinforcement processes associated with obesity generalize to non-food reinforcers. The current study compared the reinforcing effects of a fat (corn oil) and a drug of abuse (cocaine) in obese and lean Zucker rats. Specifically, obese and lean Zucker rats self-administered corn oil or intravenous cocaine in a behavioral economic demand procedure. For corn oil, maximum demand was higher and demand elasticity was lower in the obese rats compared to their lean counterparts. However, there were no differences in demand for cocaine between the obese and lean rats. These results demonstrate that a fat in the form of corn oil is a more effective reinforcer in obese Zucker rats. However, the fact that demand for cocaine was not different between the obese and lean rats suggests that differences in reward mechanisms may be reinforcer-specific and do not necessarily generalize to non-food reinforcers.
Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, The University of Mississippi Medical Center, Jackson, MS 39216, United States. Electronic address: s52drew@gmail.com.
Edward A
EA
Townsend
Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, The University of Mississippi Medical Center, Jackson, MS 39216, United States.
Lauren N
LN
Beloate
Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, The University of Mississippi Medical Center, Jackson, MS 39216, United States.
Sally L
SL
Huskinson
Institutes for Behavior Resources, Baltimore, MD 21218, United States; Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21224, United States.
Peter G
PG
Roma
Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, The University of Mississippi Medical Center, Jackson, MS 39216, United States.
Kevin B
KB
Freeman
D000818:Animals; D003042:Cocaine / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects; D003314:Corn Oil / Q000008:administration & dosage*; D004195:Disease Models, Animal; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage*; D005518:Food Preferences; D008297:Male; D009765:Obesity / Q000523:psychology / Q000628:therapy*; D051381:Rats; D011924:Rats, Zucker; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology; D012646:Self Administration; D018709:Statistics, Nonparametric
D018765:Dopamine Uptake Inhibitors; D003314:Corn Oil; D003042:Cocaine
Behavioral economics; Cocaine; Fat; Obesity; Reinforcement; Zucker rat