title: Pre-existing differences and diet-induced alterations in striatal dopamine systems of obesity-prone rats.
abstract: OBJECTIVE
  Interactions between pre-existing differences in mesolimbic function and neuroadaptations induced by consumption of fatty, sugary foods are thought to contribute to human obesity. This study examined basal and cocaine-induced changes in striatal neurotransmitter levels without diet manipulation and D2 /D3 dopamine receptor-mediated transmission prior to and after consumption of "junk-foods" in obesity-prone and obesity-resistant rats.
  
  
  METHODS
  Microdialysis and liquid chromatography-mass spectrometry were used to determine basal and cocaine-induced changes in neurotransmitter levels in real time with cocaine-induced locomotor activity. Sensitivity to the D2 /D3 dopamine receptor agonist quinpirole was examined before and after restricted junk-food exposure. Selectively bred obesity-prone and obesity-resistant rats were used.
  
  
  RESULTS
  Cocaine-induced locomotion was greater in obesity-prone rats versus obesity-resistant rats prior to diet manipulation. Basal and cocaine-induced increases in dopamine and serotonin levels did not differ. Obesity-prone rats were more sensitive to the D2 receptor-mediated effects of quinpirole, and junk-food produced modest alterations in quinpirole sensitivity in obesity-resistant rats.
  
  
  CONCLUSIONS
  These data show that mesolimbic systems differ prior to diet manipulation in susceptible versus resistant rats, and that consumption of fatty, sugary foods produce different neuroadaptations in these populations. These differences may contribute to enhanced food craving and an inability to limit food intake in susceptible individuals.
authors: Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, USA.
authors: Peter J
authors: PJ
authors: Vollbrecht
authors: Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, USA.|Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
authors: Omar S
authors: OS
authors: Mabrouk
authors: Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, USA.
authors: Andrew D
authors: AD
authors: Nelson
authors: Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, USA.|Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
authors: Robert T
authors: RT
authors: Kennedy
authors: Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, USA.
authors: Carrie R
authors: CR
authors: Ferrario
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D003042:Cocaine / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000502:physiology; D003342:Corpus Striatum / Q000378:metabolism; D018491:Dopamine Agonists / Q000494:pharmacology; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D009765:Obesity / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018491:Dopamine Agonists; D018765:Dopamine Uptake Inhibitors; D003042:Cocaine