title: Beta-galactosidase staining in the nucleus of the solitary tract of Fos-Tau-LacZ mice is unaffected by monosodium glutamate taste stimulation.
abstract: Fos-Tau-LacZ (FTL) transgenic mice are used to visualize the anatomical connectivity of neurons that express c-Fos, an immediate early gene, in response to activation. In contrast to typical c-Fos protein expression, which is localized to the nucleus of stimulated neurons, activation of the c-Fos gene results in beta galactosidase (β-gal) expression throughout the entire cytoplasm of activated cells in FTL mice; thereby making it possible to discern the morphology of c-Fos expressing cells. This can be an especially important tool in brain areas in which function may be related to cell morphology, such as the primary taste/viscerosensory brainstem nucleus of the solitary tract (nTS). Thus, to further characterize FTL activity in the brain, the current study quantified both β-gal enzymatic activity as well as c-Fos protein expression in the nTS under a variety of experimental conditions (no stimulation, no stimulation with prior overnight food and water restriction, monosodium glutamate taste stimulation, and monosodium glutamate taste stimulation with perfusion 5 h post stimulation). Contrary to previous research, we found that β-gal activity (both labeled cell bodies and overall number of labeled pixels) was unchanged across all experimental conditions. However, traditional c-Fos protein activity (both cell bodies and number of activated pixels) varied significantly across experimental conditions, with the greatest amount of c-Fos protein label found in the group that received monosodium glutamate taste stimulation. Interestingly, although many c-Fos positive cells were also β-gal positive in the taste stimulated group, some c-Fos protein labeled cells were not co-labeled with β-gal. Together, these data suggest that β-gal staining within the nTS reflects a stable population of β-gal- positive neurons whose pattern of expression is unaffected by experimental condition.
authors.affiliation: Rocky Mountain Taste & Smell Center, Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, United States of America.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Stratford
authors.affiliation: Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO, United States of America.
authors.forename: John A
authors.initials: JA
authors.lastname: Thompson
mesh_terms: D000818:Animals; D005260:Female; D007763:Lac Operon; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics* / Q000378:metabolism; D012970:Sodium Glutamate / Q000494:pharmacology*; D017552:Solitary Nucleus / Q000378:metabolism*; D013194:Staining and Labeling; D013268:Stimulation, Chemical; D013649:Taste / Q000187:drug effects / Q000235:genetics; D055697:Taste Perception / Q000187:drug effects* / Q000235:genetics; D001616:beta-Galactosidase / Q000378:metabolism*; D016875:tau Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D016875:tau Proteins; D001616:beta-Galactosidase; D012970:Sodium Glutamate