title: ADHD-like hyperactivity, with no attention deficit, in adult rats after repeated hypoxia during the equivalent of extreme prematurity.
abstract: The most common behavioural disorder seen in children and adolescents born extremely prematurely is attention deficit hyperactivity disorder (ADHD). The hyperactive/impulsive sub-type of ADHD or the inattentive sub-type or the hyperactive/impulsive/inattentive sub-type can be evident. These sub-types of ADHD can persist into adulthood. The aim of this study was to investigate the relevance of a new immature rat model of repeated hypoxic exposure to these behavioural characteristics of extreme prematurity. More specifically, this study aimed to measure ADHD-like hyperactivity in response to delayed reward, and inattention, in repeated hypoxic versus repeated normoxic rats. Sprague-Dawley rats were exposed to either repeated hypoxia or repeated normoxia during postnatal days (PN) 1-3. The rat brain during PN1-3 is generally considered to be developmentally equivalent to the human brain during extreme prematurity. The rats were then behaviourally tested at 16 months-of-age on a multiple component fixed interval-extinction test. This test detects ADHD-like hyperactivity in response to delayed reward, as well as inattention. It was found that the repeated hypoxic rats exhibited ADHD-like hyperactivity in response to delayed reward, but no attention deficit, when compared to repeated normoxic rats. These findings provide a new animal model to investigate the biological mechanisms and treatment of ADHD-like hyperactivity due to repeated hypoxia during the equivalent of extreme prematurity.
authors.affiliation: Department of Anatomy and Structural Biology, University of Otago, P.O. Box 913, Dunedin, New Zealand. dorothy.oorschot@stonebow.otago.ac.nz
authors.forename: Dorothy E
authors.initials: DE
authors.lastname: Oorschot
authors.forename: Logan
authors.initials: L
authors.lastname: Voss
authors.forename: Matthew V
authors.initials: MV
authors.lastname: Covey
authors.forename: David K
authors.initials: DK
authors.lastname: Bilkey
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Saunders
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D001921:Brain / Q000254:growth & development / Q000473:pathology / Q000503:physiopathology; D003216:Conditioning, Operant / Q000502:physiology; D004195:Disease Models, Animal; D005108:Extinction, Psychological; D005260:Female; D006948:Hyperkinesis / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D011247:Pregnancy; D051381:Rats