title: Running and addiction: precipitated withdrawal in a rat model of activity-based anorexia.
abstract: Exercise improves cardiovascular health, strengthens muscles and bones, stimulates neuroplasticity, and promotes feelings of well-being. However, when taken to extremes, exercise can develop into an addictive-like behavior. To assess the addictive potential of exercise, withdrawal symptoms following injections of 1.0 mg/kg naloxone were compared in active and inactive male and female rats. Active and inactive rats were given food for 1 hr or 24 hr/day. Additionally, a group of inactive rats was pair-fed the amount of food consumed on the previous day by food-restricted active rats. Rats fed for 1 hr/day decreased food intake and lost weight. Additionally, food-restricted active rats increased wheel running. There was a direct relationship between the intensity of running and the severity of withdrawal symptoms. Active food-restricted rats displayed the most withdrawal symptoms, followed by active rats given 24-hr access to food. Only minimal withdrawal symptoms were observed in inactive rats. These findings support the hypothesis that exercise-induced increases in endogenous opioid peptides act in a manner similar to chronic administration of opiate drugs.
authors.affiliation: Department of Psychology, Tufts University, 490 Boston Avenue, Medford, MA 02155, USA. Robin.kanarek@tufts.edu
authors.forename: Robin B
authors.initials: RB
authors.lastname: Kanarek
authors.forename: Kristen E
authors.initials: KE
authors.lastname: D'Anci
authors.forename: Nicole
authors.initials: N
authors.lastname: Jurdak
authors.forename: Wendy Foulds
authors.initials: WF
authors.lastname: Mathes
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000855:Anorexia / Q000503:physiopathology*; D001835:Body Weight / Q000187:drug effects; D004195:Disease Models, Animal; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D005260:Female; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D010805:Physical Conditioning, Animal; D051381:Rats; D020318:Rats, Long-Evans; D012727:Sex Characteristics; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*
chemical_list: D009292:Narcotic Antagonists; D009270:Naloxone