title: Activating effects of chronic variable stress in rats with different exploratory activity: association with dopamine d(1) receptor function in nucleus accumbens.
abstract: OBJECTIVE
  Rats display persistent behavioural phenotypes of low (LE) versus high (HE) exploratory activity in the exploration box paradigm. LE rats that prefer passive coping strategies show differential dopaminergic activity in the striatum. The main hypothesis of this study was that chronic variable stress (CVS) would have a higher impact on LE rats.
  
  
  METHODS
  Animals were submitted to a CVS regimen lasting 32 days that was followed by a behavioural test battery. The functional states of their dopamine D(1) and D(2) receptors were measured in the striatum and nucleus accumbens (NAcc). Cerebral oxidative metabolism was assessed via cytochrome c oxidase histochemistry in 65 brain regions.
  
  
  RESULTS
  CVS decreased weight gain, to a higher extent in LE rats, and lowered the sucrose preference after the first week, but habituation to the anhedonic effect had developed by the end of the experiment. CVS did not change the behavioural phenotypes initially assigned. No effect of stress on D(2) receptor function was found. Chronically stressed animals exhibited higher levels of social interaction and D(1) receptor-mediated cAMP accumulation in the NAcc, but not in the striatum. CVS was associated with higher oxidative metabolism levels in the anteroventral thalamus, median raphe nuclei and central periaqueductal grey matter. These changes after stress did not depend upon the exploratory phenotype.
  
  
  CONCLUSIONS
  This study revealed changes in brain biochemistry after habituation to CVS that might be implicated in successful adaptation to chronic stress.
authors.affiliation: Department of Psychology, Centre of Behavioural and Health Sciences, University of Tartu, Tartu, Estonia.
authors.forename: Denis
authors.initials: D
authors.lastname: Matrov
authors.forename: Argo
authors.initials: A
authors.lastname: Vonk
authors.forename: Laura
authors.initials: L
authors.lastname: Herm
authors.forename: Ago
authors.initials: A
authors.lastname: Rinken
authors.forename: Jaanus
authors.initials: J
authors.lastname: Harro
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology; D002908:Chronic Disease; D000242:Cyclic AMP / Q000378:metabolism; D004195:Disease Models, Animal; D003576:Electron Transport Complex IV / Q000378:metabolism; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology*; D005518:Food Preferences / Q000187:drug effects / Q000523:psychology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000493:pharmacokinetics; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D012919:Social Behavior; D013315:Stress, Psychological / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D013395:Sucrose / Q000008:administration & dosage; D013460:Sulfur Isotopes / Q000493:pharmacokinetics; D013550:Swimming / Q000523:psychology; D013997:Time Factors
chemical_list: D017447:Receptors, Dopamine D1; D013460:Sulfur Isotopes; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D013395:Sucrose; D000242:Cyclic AMP; D003576:Electron Transport Complex IV