title: Regulation of α-Transducin and α-Gustducin Expression by a High Protein Diet in the Pig Gastrointestinal Tract.
abstract: BACKGROUND
  The expression of taste receptors (TASRs) and their signalling molecules in the gastrointestinal (GI) epithelial cells, including enteroendocrine cells (EECs), suggests they participate in chemosensing mechanisms influencing GI physiology via the release of endocrine messengers. TASRs mediate gustatory signalling by interacting with different transducers, including α-gustducin (Gαgust) and α-transducin (Gαtran) G protein subunits. This study tested whether Gαtran and Gαgust immunoreactive (-IR) cells are affected by a short-term (3 days) and long-term (30 days) high protein (Hp) diet in the pig GI tract.
  
  
  RESULTS
  In the stomach, Gαgust and Gαtran-IR cells contained serotonin (5-HT) and ghrelin (GHR), while in the small and large intestine, Gαgust and Gαtran-IR colocalized with 5-HT-, cholecystokinin (CCK)- and peptide YY (PYY)-IR. There was a significant increase in the density of Gαtran-IR cells in the pyloric mucosa in both short- and long-term Hp diet groups (Hp3 and Hp30) vs. the control group (Ctr) (P<0.05), while the increase of Gαgust-IR cells in the pyloric mucosa was significant in Hp30 group vs. Ctr and vs. Hp3 (P<0.05); these cells included Gαtran / 5HT-IR and Gαtran / GHR-IR cells (P<0.05 and P<0.001 vs. Ctr, respectively) as well as Gαgust /5-HT-IR or Gαgust / GHR-IR cells (P<0.05 and P<0.01 vs. Ctr, respectively). In the small intestine, we recorded a significant increase in Gαtran-IR cells in the duodenal crypts and a significant increase of Gαgust-IR cells in the jejunal crypts in Hp3 group compared to HP30 (P<0.05). With regard to the number of Gαtran-Gαgust IR cells colocalized with CCK or 5-HT, there was only a significant increase of Gαtran / CCK-IR cells in Hp3 group compared to Ctr (P = 0.01).
  
  
  CONCLUSIONS
  This study showed an upregulation of selected subpopulations of Gαgust / Gαtran-IR cells in distinct regions of the pig GI tract by short- and long-term Hp diet lending support to TASR-mediated effects in metabolic homeostasis and satiety mechanisms.
authors.affiliation: Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: De Giorgio
authors.affiliation: Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Mazzoni
authors.affiliation: Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Vallorani
authors.affiliation: Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Rocco
authors.initials: R
authors.lastname: Latorre
authors.affiliation: Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Cristiano
authors.initials: C
authors.lastname: Bombardi
authors.affiliation: Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Bacci
authors.affiliation: Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Forni
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Mirella
authors.initials: M
authors.lastname: Falconi
authors.affiliation: CURE Digestive Diseases Research Center, Digestive Diseases Division, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.|Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.|Veterans Administration, Greater Los Angeles Health system, Los Angeles, California, United States of America.
authors.forename: Catia
authors.initials: C
authors.lastname: Sternini
authors.affiliation: Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Clavenzani
mesh_terms: D000818:Animals; D004032:Diet; D004044:Dietary Proteins / Q000378:metabolism*; D005260:Female; D041981:Gastrointestinal Tract / Q000378:metabolism*; D054439:Ghrelin / Q000032:analysis / Q000378:metabolism; D012701:Serotonin / Q000032:analysis / Q000378:metabolism; D034421:Sus scrofa / Q000378:metabolism*; D015293:Transducin / Q000032:analysis / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D054439:Ghrelin; C075192:gustducin; D012701:Serotonin; D015293:Transducin