title: Excessive nest building is a unique behavioural phenotype in the deer mouse model of obsessive-compulsive disorder.
abstract: Obsessive-compulsive disorder (OCD) is a phenotypically heterogeneous condition characterised by time-consuming intrusive thoughts and/or compulsions. Irrespective of the symptom type diagnosed, the severity of OCD is characterised by heterogeneity in symptom presentation that complicates diagnosis and treatment. Heterogeneity of symptoms would be invaluable in an animal model. Nest building behaviour forms part of the normal behavioural repertoire of rodents and demonstrates profound between-species differences. However, it has been proposed that within-species differences in nest building behaviour (i.e. aberrant vs. normal nest building) may resemble obsessive-compulsive-like symptoms. In an attempt to investigate whether other obsessive-compulsive-like behaviours are present in an animal model of OCD, or if aberrant nest building behaviour may represent a unique obsessive-compulsive phenotype in such a model, the current study assessed nest building behaviour in high (H, viz obsessive-compulsive) and non (N, viz normal) stereotypical deer mice. Subsequently, 12 N and H animals, respectively, were provided with an excess of cotton wool daily for one week prior to and following four weeks of high-dose oral escitalopram treatment (50 mg/kg/day). Data from the current investigation demonstrate daily nesting activity to be highly variable in deer mice, with stereotypy and nest building being independent behaviours. However, we identified unique aberrant large nest building behaviour in 30% of animals from both cohorts that was attenuated by escitalopram to pre-treatment nesting scores of the larger group. In summary, behavioural and drug-treatment evidence confirms that deer mouse behaviour does indeed resemble symptom heterogeneity related to OCD, and as such expands its face and predictive validity for the disorder.
authors.affiliation: Division of Pharmacology, North-West University, Potchefstroom, South Africa.
authors.forename: De Wet
authors.initials: de W
authors.lastname: Wolmarans
authors.affiliation: Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa.
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Stein
authors.affiliation: Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa brian.harvey@nwu.ac.za.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Harvey
mesh_terms: D000818:Animals; D015283:Citalopram / Q000008:administration & dosage / Q000494:pharmacology*; D004195:Disease Models, Animal; D009425:Nesting Behavior / Q000187:drug effects / Q000502:physiology*; D009771:Obsessive-Compulsive Disorder / Q000503:physiopathology*; D010542:Peromyscus; D010641:Phenotype; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D013045:Species Specificity; D013239:Stereotyped Behavior / Q000187:drug effects / Q000502:physiology*
chemical_list: D015283:Citalopram; D017367:Selective Serotonin Reuptake Inhibitors
keywords: Deer mouse; OCD animal model; SSRI response; perseverative behaviour; symptom heterogeneity