title: Physical exercise affects attentional orienting behavior through noradrenergic mechanisms.
abstract: Spontaneously hypertensive rats (SHRs), a commonly used animal model of attention-deficit/hyperactivity disorder, exhibit little habituation of the orienting response to repeated presentations of a nonreinforced visual stimulus. However, SHRs that have access to a running wheel for 5, 10, or 21 days exhibit robust habituation that is indistinguishable from normo-active rats. Two days of exercise, in comparison, is not sufficient to affect habituation. Here we tested the hypothesis that the effect of exercise on orienting behavior in SHRs is mediated by changes in noradrenergic function. In Experiment 1, we found that 5, 10, or 21 days of access to a running wheel, but not 2 days, significantly reduced levels of the norepinephrine transporter in medial prefrontal cortex. In Experiment 2, we tested for a causal relationship between changes in noradrenergic function and orienting behavior by blocking noradrenergic receptors during exercise. Rats that received propranolol (beta adrenergic/noradrenergic receptor blocker) during 10 days of exercise failed to exhibit an exercise-induced reduction in orienting behavior. The results inform a growing literature regarding the effects of exercise on behavior and the potential use of exercise as a treatment for mental disorders.
authors.affiliation: Department of Psychological and Brain Sciences, Dartmouth College.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Robinson
authors.affiliation: Department of Neurological Sciences, College of Medicine, University of Vermont.
authors.forename: Thomas
authors.initials: T
authors.lastname: Buttolph
authors.affiliation: Department of Neurological Sciences, College of Medicine, University of Vermont.
authors.forename: John T
authors.initials: JT
authors.lastname: Green
authors.affiliation: Department of Psychological and Brain Sciences, Dartmouth College.
authors.forename: David J
authors.initials: DJ
authors.lastname: Bucci
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology; D015153:Blotting, Western; D004195:Disease Models, Animal; D005260:Female; D009638:Norepinephrine / Q000378:metabolism*; D009949:Orientation / Q000187:drug effects / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D017397:Prefrontal Cortex / Q000187:drug effects / Q000503:physiopathology*; D011433:Propranolol / Q000494:pharmacology; D011918:Rats, Inbred SHR; D012420:Running / Q000502:physiology*; D013997:Time Factors
chemical_list: D000319:Adrenergic beta-Antagonists; D011433:Propranolol; D009638:Norepinephrine