title: Three-dimensional macronutrient-associated Fos expression patterns in the mouse brainstem.
abstract: BACKGROUND
  The caudal brainstem plays an important role in short-term satiation and in the control of meal termination. Meal-related stimuli sensed by the gastrointestinal (GI) tract are transmitted to the area postrema (AP) via the bloodstream, or to the nucleus tractus solitarii (NTS) via the vagus nerve. Little is known about the encoding of macronutrient-specific signals in the caudal brainstem. We hypothesized that sucrose and casein peptone activate spatially distinct sub-populations of NTS neurons and thus characterized the latter using statistical three-dimensional modeling.
  
  
  RESULTS
  Using immunolabeling of the proto-oncogene Fos as a marker of neuronal activity, in combination with a statistical three-dimensional modeling approach, we have shown that NTS neurons activated by sucrose or peptone gavage occupy distinct, although partially overlapping, positions. Specifically, when compared to their homologues in peptone-treated mice, three-dimensional models calculated from neuronal density maps following sucrose gavage showed that Fos-positive neurons occupy a more lateral position at the rostral end of the NTS, and a more dorsal position at the caudal end.
  
  
  CONCLUSIONS
  To our knowledge, this is the first time that subpopulations of NTS neurons have be distinguished according to the spatial organization of their functional response. Such neuronal activity patterns may be of particular relevance to understanding the mechanisms that support the central encoding of signals related to the presence of macronutrients in the GI tract during digestion. Finally, this finding also illustrates the usefulness of statistical three-dimensional modeling to functional neuroanatomical studies.
authors.affiliation: AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France.
authors.forename: Jessica
authors.initials: J
authors.lastname: Schwarz
authors.forename: Jasmine
authors.initials: J
authors.lastname: Burguet
authors.forename: Olivier
authors.initials: O
authors.lastname: Rampin
authors.forename: Gilles
authors.initials: G
authors.lastname: Fromentin
authors.forename: Philippe
authors.initials: P
authors.lastname: Andrey
authors.forename: Daniel
authors.initials: D
authors.lastname: Tomé
authors.forename: Yves
authors.initials: Y
authors.lastname: Maurin
authors.forename: Nicolas
authors.initials: N
authors.lastname: Darcel
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000033:anatomy & histology* / Q000166:cytology / Q000378:metabolism*; D002364:Caseins / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D019422:Dietary Sucrose / Q000008:administration & dosage; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008953:Models, Anatomic; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D017552:Solitary Nucleus / Q000033:anatomy & histology / Q000166:cytology / Q000378:metabolism; D013395:Sucrose / Q000008:administration & dosage
chemical_list: D002364:Caseins; D004044:Dietary Proteins; D019422:Dietary Sucrose; D016760:Proto-Oncogene Proteins c-fos; D013395:Sucrose