title: Effect of increasing body condition on key regulators of fat metabolism in subcutaneous adipose tissue depot and circulation of nonlactating dairy cows.
abstract: In response to negative energy balance, overconditioned cows mobilize more body fat than thin cows and subsequently are prone to develop metabolic disorders. Changes in adipose tissue (AT) metabolism are barely investigated in overconditioned cows. Therefore, the objective was to investigate the effect of increasing body condition on key regulator proteins of fat metabolism in subcutaneous AT and circulation of dairy cows. Nonlactating, nonpregnant dairy cows (n=8) investigated in the current study served as a model to elucidate the changes in the course of overcondition independent from physiological changes related to gestation, parturition, and lactation. Cows were fed diets with increasing portions of concentrate during the first 6wk of the experiment until 60% were reached, which was maintained for 9wk. Biopsy samples from AT of the subcutaneous tailhead region were collected every 8wk, whereas blood was sampled monthly. Within the experimental period cows had an average BW gain of 243±33.3 kg. Leptin and insulin concentrations were increased until wk 12. Based on serum concentrations of glucose, insulin, and nonesterified fatty acids, the surrogate indices for insulin sensitivity were calculated. High-concentrate feeding led to decreased quantitative insulin sensitivity check index and homeostasis model assessment due to high insulin and glucose concentrations indicating decreased insulin sensitivity. Adiponectin, an adipokine-promoting insulin sensitivity, decreased in subcutaneous AT, but remained unchanged in the circulation. The high-concentrate diet affected key enzymes reflecting AT metabolism such as AMP-activated protein kinase and hormone-sensitive lipase, both represented as the proportion of the phosphorylated protein to total protein, as well as fatty acid synthase. The extent of phosphorylation of AMP-activated protein kinase and the protein expression of fatty acid synthase were inversely regulated throughout the experimental period, whereas the extent of phosphorylation of hormone-sensitive lipase was consistently decreasing by the high-concentrate diet. Overcondition in nonpregnant, nonlactating dairy cows changed the expression of key regulator proteins of AT metabolism and circulation accompanied by impaired insulin sensitivity, which might increase the risk for metabolic disorders.
authors.affiliation: Clinic for Cattle, University of Veterinary Medicine Hannover, Foundation, 30173 Hannover, Germany. Electronic address: L.locher@med.vetmed.uni-muenchen.de.
authors.forename: L
authors.initials: L
authors.lastname: Locher
authors.affiliation: Institute of Animal Science, Physiology & Hygiene Unit, University of Bonn, 53115 Bonn, Germany. Electronic address: Susanne.Haeussler@uni-bonn.de.
authors.forename: S
authors.initials: S
authors.lastname: Häussler
authors.affiliation: Institute of Animal Science, Physiology & Hygiene Unit, University of Bonn, 53115 Bonn, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Laubenthal
authors.affiliation: Institute of Animal Science, Physiology & Hygiene Unit, University of Bonn, 53115 Bonn, Germany.
authors.forename: S P
authors.initials: SP
authors.lastname: Singh
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler Institute (FLI), Federal Research Institute for Animal Health, 38116 Braunschweig, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Winkler
authors.affiliation: Clinic for Cattle, University of Veterinary Medicine Hannover, Foundation, 30173 Hannover, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kinoshita
authors.affiliation: Department of Physiology, University of Veterinary Medicine Hannover, Foundation, 30173 Hannover, Germany.
authors.forename: Á
authors.initials: Á
authors.lastname: Kenéz
authors.affiliation: Clinic for Cattle, University of Veterinary Medicine Hannover, Foundation, 30173 Hannover, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Rehage
authors.affiliation: Department of Physiology, University of Veterinary Medicine Hannover, Foundation, 30173 Hannover, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Huber
authors.affiliation: Institute of Animal Science, Physiology & Hygiene Unit, University of Bonn, 53115 Bonn, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Sauerwein
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler Institute (FLI), Federal Research Institute for Animal Health, 38116 Braunschweig, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Dänicke
mesh_terms: D055372:AMP-Activated Protein Kinases; D052242:Adiponectin / Q000378:metabolism; D000818:Animals; D001823:Body Composition; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D004734:Energy Metabolism / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D007774:Lactation / Q000502:physiology; D020738:Leptin; D050356:Lipid Metabolism; D036801:Parturition; D002787:Sterol Esterase / Q000378:metabolism; D050151:Subcutaneous Fat / Q000378:metabolism*
chemical_list: D052242:Adiponectin; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D020738:Leptin; D055372:AMP-Activated Protein Kinases; D002787:Sterol Esterase; D005947:Glucose
keywords: dairy cow; fat metabolism; subcutaneous adipose tissue