Rearing in an enriched environment attenuated hyperactivity and inattention in the Spontaneously Hypertensive Rats, an animal model of Attention-Deficit Hyperactivity Disorder

• Published in: Physiology & behavior Vol. 155; pp. 30 - 37
• Main Authors: Botanas, Chrislean Jun, Lee, Hyelim, de la Peña, June Bryan, dela Peña, Irene Joy, Woo, Taeseon, Kim, Hee Jin, Han, Doug Hyun, Kim, Bung-Nyun, Cheong, Jae Hoon
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2016
• Subjects: Animals; Attention - physiology; Attention Deficit Disorder with Hyperactivity - physiopathology; Attention Deficit Disorder with Hyperactivity - therapy; Attention deficit hyperactivity disorder; Brain - physiopathology; Cohort Studies; Delay Discounting - physiology; Disease Models, Animal; Electrocorticography; Environment; Environmental enrichment; Housing, Animal; Male; Maze Learning - physiology; Motor Activity - physiology; Psychiatry; Rats, Inbred SHR; Rats, Inbred WKY; Spontaneously Hypertensive Rats; Wistar-Kyoto rats; Spontaneously Hypertensive Rats; Wistar-Kyoto rats; Attention deficit hyperactivity disorder; Environmental enrichment
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/j.physbeh.2015.11.035

Abstract Attention-deficit hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder, characterized by symptoms of hyperactivity, inattention, and impulsivity. It is commonly treated with psychostimulants that typically begins during childhood and lasts for an extended period of time. However, there are concerns regarding the consequences of chronic psychostimulant treatment; thus, there is a growing search for an alternative management for ADHD. One non-pharmacological management that is gaining much interest is environmental enrichment. Here, we investigated the effects of rearing in an enriched environment (EE) on the expression of ADHD-like symptoms in the Spontaneously Hypertensive Rats (SHRs), an animal model of ADHD. SHRs were reared in EE or standard environment (SE) from post-natal day (PND) 21 until PND 49. Thereafter, behavioral tests that measure hyperactivity (open field test [OFT]), inattention (Y-maze task), and impulsivity (delay discounting task) were conducted. Additionally, electroencephalography (EEG) was employed to assess the effects of EE on rat's brain activity. Wistar-Kyoto (WKY) rats, the normotensive counterpart of the SHRs, were used to determine whether the effects of EE were specific to a particular genetic background. EE improved the performance of the SHRs and WKY rats in the OFT and Y-maze task, but not the delay discounting task. Interestingly, EE induced significant EEG changes in WKY rats, but not in the SHRs. These findings show that rearing environment may play a role in the expression of ADHD-like symptoms in the SHRs and that EE may be considered as a putative complementary approach in managing ADHD symptoms.