title: Conditioned taste aversion with lipopolysaccharide and peptidoglycan does not activate cytokine gene expression in the spleen and hypothalamus of mice.
abstract: Several reports show that behavioural and physiological components of the acute phase reaction can be conditioned. However, the mechanisms responsible for these effects remain obscure. The underlying assumption that the changes observed in conditioned animals are dependent on a conditioned production of cytokines has never been demonstrated. In the present study, the possibility of conditioning the production of cytokines or molecules implicated in their signalling pathways was tested by submitting mice to conditioned taste aversion with a new saccharin taste paired with intraperitoneal (i.p.) injections of lipopolysaccharide (LPS, 0.83 microg/g) or peptidoglycan (PGN, 20 microg/g). After two conditioning sessions, conditioned mice developed a clear aversion to saccharine that was not associated with activation of genes of the cytokine network either at the periphery, or in the hypothalamus, as demonstrated by a macroarray approach and confirmed by real time RT-PCR. In contrast, there was an activation of the genes coding for nuclear factor kappa B (NFkappaB) and mitogen activated protein kinase (MAPK) signalling pathways in the spleen and to a lesser extent in the hypothalamus. This modulation of the NFkappaB and MAPK signalling pathways is interpreted in terms of a possible conditioned sensitisation of the immune system.
authors.affiliation: INRA-INSERM U394: Neurobiologie Intégrative, Institut François Magendie, Rue Camille Saint-Saëns, 3307 Bordeaux Cedex, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Mormède
authors.forename: Karine
authors.initials: K
authors.lastname: Palin
authors.forename: Keith W
authors.initials: KW
authors.lastname: Kelley
authors.forename: Nathalie
authors.initials: N
authors.lastname: Castanon
authors.forename: Robert
authors.initials: R
authors.lastname: Dantzer
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001245:Association Learning / Q000502:physiology*; D001362:Avoidance Learning / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008070:Lipopolysaccharides; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D015213:Neuroimmunomodulation / Q000502:physiology; D010457:Peptidoglycan; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction; D013154:Spleen / Q000187:drug effects / Q000378:metabolism*; D013649:Taste; D013651:Taste Disorders / Q000139:chemically induced / Q000378:metabolism
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010457:Peptidoglycan; D012333:RNA, Messenger; D020928:Mitogen-Activated Protein Kinases; D003345:Corticosterone