title: Differential sensitivity to amphetamine's effect on open field behavior of psychosocially stressed male rats.
abstract: BACKGROUND
  Studies of socially housed rodents have provided significant information regarding the mechanisms of stress and of stress-related disorders.
  
  
  OBJECTIVE
  Since psychosocial stress is known to alter the functional activity of dopaminergic system, we employed amphetamine (AMP) to evaluate the involvement dopamine in mediating the behavioral consequences of psychosocial stress.
  
  
  METHODS
  Male rats housed two per cage were designated as dominant (DOM) or subdominant (Sdom) based on initial evaluations of agonistic behaviors and body weight changes. Diad-housed rats and a group of single-housed (SiH) rats were tested in an open field after injections of saline or amphetamine (0.9 or 2.7 mg/kg IP) prior to and again while diad-housing.
  
  
  RESULTS
  Compared to future DOM rats, saline-injected future Sdom rats entered the open field center less frequently, spent less time in rearing behavior and groomed less. At the pre-diad test AMP treatment elevated locomotor activity of all rats, while stimulation of center entries was more marked in future DOM rats. At the diad test, AMP's locomotor stimulant effect was evident in all experimental groups with DOM rats showing higher effects compared to Sdom and SiH rats. Amphetamine's stimulation of center entries in DOM rats was similar to the pre-diad test, but it was diminished in Sdom rats, while stimulation of rearing behavior was most evident in diad-housed rats.
  
  
  CONCLUSIONS
  The dopaminergic system modulates the psychosocial stress-induced differences in explorative and emotional behaviors. Furthermore, behavioral traits like frequency of grooming behavior and of center entries were predictive of future hierarchical status.
authors.affiliation: Center of Alcohol Studies, Rurgers University, 607 Allison Road, Piscataway, NJ 08854-1100, USA. larissa@rci.rutgers.edu
authors.forename: Larissa A
authors.initials: LA
authors.lastname: Pohorecky
authors.forename: April
authors.initials: A
authors.lastname: Sweeny
authors.forename: Patricia
authors.initials: P
authors.lastname: Buckendahl
mesh_terms: D000661:Amphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005106:Exploratory Behavior / Q000187:drug effects; D006120:Grooming / Q000187:drug effects; D006799:Housing, Animal; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D020318:Rats, Long-Evans; D012930:Social Dominance; D013315:Stress, Psychological
chemical_list: D000661:Amphetamine; D004298:Dopamine