title: Mesolimbic dopamine D₂ receptor plasticity contributes to stress resilience in rats subjected to chronic mild stress.
abstract: BACKGROUND
  Few studies have investigated neurobiological and biochemical differences between stress-resilient and stress-vulnerable experimental animals.
  
  
  OBJECTIVE
  We investigated alterations in mesolimbic dopamine D2 receptor density and mRNA expression level in stressed rats at two time points, i.e. after 2 and 5 weeks of chronic mild stress (CMS).
  
  
  METHODS
  We used the chronic mild stress paradigm because it is a well-established animal model of depression. Two groups of stressed rats were distinguished during CMS experiments: (1) stress reactive (70 %), which displayed a decrease in the drinking of a palatable sucrose solution during the stress regimen, and (2) stress resilient (30 %), which exhibited an unaltered drinking profile when compared with the unchallenged control group. [(3)H]Domperidone was used as a ligand to label dopamine D2 receptors, and a mixture of three specific oligonucleotides was used to evaluate dopamine D2 receptor mRNA changes in various regions of the rat brain.
  
  
  RESULTS
  CMS strongly affected the mesolimbic dopamine circuit in stress-resilient group after 2 weeks and stress-reactive group of rats after 5 weeks which exhibited a decrease in the level of dopamine D2 receptor protein without alterations in D2 mRNA expression. Stress-resilient animals, but not stress-reactive animals, effectively adapted to the extended stress and coped with it. The increase in D2 mRNA expression returned the dopamine D2 receptor density to control levels in stress-resilient rats after 5 weeks of CMS, but not in stress-reactive animals.
  
  
  CONCLUSIONS
  These results clearly demonstrate that, despite earlier blunting, the activation of dopamine receptor biosynthesis in the dopamine mesoaccumbens system in stress-resilient rats is involved in active coping with stressful experiences, and it exhibits a delay in time.
authors: Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland.
authors: Dariusz
authors: D
authors: Zurawek
authors: Agata
authors: A
authors: Faron-Górecka
authors: Maciej
authors: M
authors: Kuśmider
authors: Magdalena
authors: M
authors: Kolasa
authors: Piotr
authors: P
authors: Gruca
authors: Mariusz
authors: M
authors: Papp
authors: Marta
authors: M
authors: Dziedzicka-Wasylewska
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D003863:Depression / Q000503:physiopathology*; D004195:Disease Models, Animal; D004294:Domperidone / Q000378:metabolism; D005786:Gene Expression Regulation; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism*; D013315:Stress, Psychological / Q000503:physiopathology*; D013395:Sucrose / Q000008:administration & dosage; D013997:Time Factors
chemical_list: D012333:RNA, Messenger; D017448:Receptors, Dopamine D2; D004294:Domperidone; D013395:Sucrose
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