title: Associations between Forkhead Box O1 (FoxO1) Expression and Indicators of Hepatic Glucose Production in Transition Dairy Cows Supplemented with Dietary Nicotinic Acid.
abstract: Forkhead box protein O1 (FoxO1) is a transcription factor which promotes hepatic glucose production (HGP) by up-regulating the transcription of gluconeogenic enzymes in monogastric species. The activity of FoxO1 is inhibited by insulin-induced phosphorylation. The aims of the present study were to find associations between FoxO1 expression and variables associated with HGP as affected by feeding regimen in dairy cows during the transition period. Twenty one healthy German Holstein cows were allocated to four groups (LC-CON, HC-CON, LC-NA with 5 cows/group and HC-NA with 6 cows/group, respectively). Cows received 0 (LC-CON and HC-CON) or 24 (LC-NA and HC-NA) g/d nicotinic acid with high (HC) or low (LC) concentrate proportion from -42 days (-41.8 + 4.8; mean + standard deviation) relative to expected calving date (d-42) to d24. Liver biopsy was taken at d-42, 1, 21, and 100. The total protein expression of FoxO1 (tFoxO1) and the extent of phosphorylation of FoxO1 at serine 256 (pFoxO1) were analysed semiquantitatively by Western Blotting. The expression of hepatic mRNA of FoxO1 and seven genes associated with HGP was measured by real-time RT-PCR. Mixed model and Pearson's correlation were used for statistical evaluation with the level of significance at P<0.05. No dietary effect was observed either on feed intake, energy balance, or on the concentration of blood metabolites. Neither time nor diet affected the expression of FoxO1 total protein and mRNA. A NA × concentrate interaction was found in pFoxO1. However, no corresponding dietary effect was found in the mRNA expression of investigated genes. Different patterns of correlations between FoxO1-related variables and investigated indicators for HGP were found at d21 and 100. The results indicated that the regulation of HGP did not take place on the levels of mRNA and protein expression and the phosphorylation of FoxO1 in dairy cows in early lactation.
authors.affiliation: Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Lower Saxony, Germany.
authors.forename: Asako
authors.initials: A
authors.lastname: Kinoshita
authors.affiliation: Clinic for Ruminants with Ambulatory and Herd Health Services at the Center of Veterinary Clinical Medicine, Ludwig-Maximilians-University Munich, Munich, Bavaria, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Locher
authors.affiliation: Institute of Animal Nutrition, Federal Research Institute for Animal Health, Friedrich-Loeffler-Institute, Braunschweig, Lower Saxony, Germany.
authors.forename: Reka
authors.initials: R
authors.lastname: Tienken
authors.affiliation: Institute of Animal Nutrition, Federal Research Institute for Animal Health, Friedrich-Loeffler-Institute, Braunschweig, Lower Saxony, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Meyer
authors.affiliation: Institute of Animal Nutrition, Federal Research Institute for Animal Health, Friedrich-Loeffler-Institute, Braunschweig, Lower Saxony, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Dänicke
authors.affiliation: Clinic for Cattle, University of Veterinary Medicine Hannover, Foundation, Hannover, Lower Saxony, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Rehage
authors.affiliation: Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Lower Saxony, Germany.
authors.forename: Korinna
authors.initials: K
authors.lastname: Huber
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle; D004032:Diet; D019587:Dietary Supplements / Q000032:analysis*; D004734:Energy Metabolism / Q000187:drug effects* / Q000502:physiology; D005260:Female; D051858:Forkhead Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000096:biosynthesis / Q000378:metabolism; D007328:Insulin / Q000097:blood; D008099:Liver / Q000378:metabolism; D008892:Milk / Q000378:metabolism; D009525:Niacin / Q000494:pharmacology*; D010766:Phosphorylation
chemical_list: D051858:Forkhead Transcription Factors; D007328:Insulin; D009525:Niacin; D005947:Glucose