title: Changes in the incentive value of food after naltrexone treatment depend on a differential preference for a palatable food in male rats.
abstract: BACKGROUND
  Opioid antagonist treatments such as naltrexone (NTX) and naloxone reduce consummatory behavior of palatable food (PF) and other incentives. Meanwhile, a significant increase in alcohol consumption has been observed when it is offered immediately after ending NTX treatment, an effect apparently produced by increased opioidergic activity caused by up-regulation of opioid receptors.
  
  
  OBJECTIVE
  On this basis we assessed changes in the consumption of PF after opioid antagonist treatment in rats with different preferences for that food.
  
  
  METHODS
  The preference of male Wistar rats for a PF was classified as low, medium, or high in a baseline period, after which the animals in each preference level were sub-divided into control and experimental groups that received injections of either NTX (2 mg/kg twice per day/6 days) or a saline solution with a space of 8 hours between doses. At the end of pharmacological treatment (PT), subjects were re-exposed to the PF.
  
  
  RESULTS
  Increased PF intake was found only in the low-preference group, but the increase was observed in both the experimental and control animals. Also, a decrease in chow intake during PT was observed in all preference groups, while recovery after treatment was noted only in the low-preference rats.
  
  
  CONCLUSIONS
  The increased intake observed in the low-preference rats after treatment phase suggests that the hypothalamic-pituitary-adrenal axis activation during PT could have enhanced the rewarding characteristics of the sweet food and so facilitated and increased its consumption in the re-exposure period.
authors.affiliation: a Laboratorio de Farmacología y Conducta , Instituto de Neurociencias, CUCBA, Universidad de Guadalajara , Guadalajara , Jalisco CP 44130 , México.
authors.forename: Mariana
authors.initials: M
authors.lastname: Alvarado-Bañuelos
authors.affiliation: a Laboratorio de Farmacología y Conducta , Instituto de Neurociencias, CUCBA, Universidad de Guadalajara , Guadalajara , Jalisco CP 44130 , México.
authors.forename: Eliana
authors.initials: E
authors.lastname: Barrios De Tomasi
authors.affiliation: a Laboratorio de Farmacología y Conducta , Instituto de Neurociencias, CUCBA, Universidad de Guadalajara , Guadalajara , Jalisco CP 44130 , México.
authors.forename: Jorge
authors.initials: J
authors.lastname: Juárez
mesh_terms: D000818:Animals; D001835:Body Weight; D002755:Choice Behavior; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004435:Eating; D005518:Food Preferences; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009042:Motivation; D009271:Naltrexone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000235:genetics / Q000378:metabolism
chemical_list: D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D009271:Naltrexone
keywords: Carbohydrate intake; Eating behavior; Food intake; Incentive value; Naltrexone; Opioid antagonist; Opioid system; Palatable food