The role of indoleamine 2,3-dioxygenase in a mouse model of neuroinflammation-induced depression

  • Nikoletta Dobos
  • Erik F J de Vries
  • Ido P Kema
  • Konstantinos Patas
  • Marloes Prins
  • Ingrid M Nijholt
  • Rudi A Dierckx
  • Jakob Korf
  • Johan A den Boer
  • Paul G M Luiten
  • Ulrich L M Eisel

Abstract

Indoleamine 2,3-dioxygenase (IDO), an enzyme which is activated by pro-inflammatory cytokines, has been suggested as a potential link between neuroinflammatory processes in neurodegenerative diseases (like Alzheimer's disease) and depression. The present study aimed to determine whether neuroinflammation-induced increased IDO levels in the mammalian brain will lead to depressive-like behavior. Neuroinflammation was initiated in mice by a single intracerebroventricular injection of lipopolysaccharide (LPS). Cerebral inflammation was monitored 1, 2, 3 and 4 days after the injection with small-animal positron emission tomography (PET) using the inflammatory marker [(11)C]-PK11195. In the presence or absence of systemically applied 1-methyl-tryptophan (1-MT), a competitive IDO-inhibitor, we assessed the development of depressive-like behavioral symptoms in parallel with IDO expression and activity. The PK11195 PET signal reached a highly significant peak 3 days after LPS injection, while these animals displayed a significant increase of depressive-like behavior in the forced swim test compared to vehicle-injected animals. These findings were paralleled by a significant increase of IDO in the brainstem, and an increased kynurenine/tryptophan ratio in the serum. Moreover, we report here for the first time, that inhibition of IDO by 1-MT in centrally induced neuroinflammation under experimental conditions can prevent the development of depressive-like behavior.

Bibliografische Daten

OriginalspracheEnglisch
ISSN1387-2877
DOIs
StatusVeröffentlicht - 2012
Extern publiziertJa
PubMed 22112548