title: Insulin Sensitivity in Adipose and Skeletal Muscle Tissue of Dairy Cows in Response to Dietary Energy Level and 2,4-Thiazolidinedione (TZD).
abstract: The effects of dietary energy level and 2,4-thiazolidinedione (TZD) injection on feed intake, body fatness, blood biomarkers and TZD concentrations, genes related to insulin sensitivity in adipose tissue (AT) and skeletal muscle, and peroxisome proliferator-activated receptor gamma (PPARG) protein in subcutaneous AT (SAT) were evaluated in Holstein cows. Fourteen nonpregnant nonlactating cows were fed a control low-energy (CON, 1.30 Mcal/kg) diet to meet 100% of estimated nutrient requirements for 3 weeks, after which half of the cows were assigned to a higher-energy diet (OVE, 1.60 Mcal/kg) and half of the cows continued on CON for 6 weeks. All cows received an intravenous injection of TZD starting 2 weeks after initiation of dietary treatments and for an additional 2 weeks, which served as the washout period. Cows fed OVE had greater energy intake and body mass than CON, and TZD had no effect during the administration period. The OVE cows had greater TZD clearance rate than CON cows. The lower concentration of nonesterified fatty acids (NEFA) and greater concentration of insulin in blood of OVE cows before TZD injection indicated positive energy balance and higher insulin sensitivity. Administration of TZD increased blood concentrations of glucose, insulin, and beta-hydroxybutyrate (BHBA) at 2 to 4 weeks after diet initiation, while the concentration of NEFA and adiponectin (ADIPOQ) remained unchanged during TZD. The TZD upregulated the mRNA expression of PPARG and its targets FASN and SREBF1 in SAT, but also SUMO1 and UBC9 which encode sumoylation proteins known to down-regulate PPARG expression and curtail adipogenesis. Therefore, a post-translational response to control PPARG gene expression in SAT could be a counteregulatory mechanism to restrain adipogenesis. The OVE cows had greater expression of the insulin sensitivity-related genes IRS1, SLC2A4, INSR, SCD, INSIG1, DGAT2, and ADIPOQ in SAT. In skeletal muscle, where PPARA and its targets orchestrate carbohydrate metabolism and fatty acid oxidation, the OVE cows had greater glyceroneogenesis (higher mRNA expression of PC and PCK1), whereas CON cows had greater glucose transport (SLC2A4). Administration of TZD increased triacylglycerol concentration and altered expression of carbohydrate- and fatty acid oxidation-related genes in skeletal muscle. Results indicate that overfeeding did not affect insulin sensitivity in nonpregnant, nonlactating dairy cows. The bovine PPARG receptor appears TZD-responsive, with its activation potentially leading to greater adipogenesis and lipogenesis in SAT, while differentially regulating glucose homeostasis and fatty acid oxidation in skeletal muscle. Targeting PPARG via dietary nutraceuticals while avoiding excessive fat deposition might improve insulin sensitivity in dairy cows during times such as the peripartal period when the onset of lactation naturally decreases systemic insulin release and sensitivity in tissues such as AT.
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois 61801, United States of America.|University of Bonn, Bonn, NRW 53115, Germany.
authors.forename: Afshin
authors.initials: A
authors.lastname: Hosseini
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois 61801, United States of America.
authors.forename: Muhammad Rizwan
authors.initials: MR
authors.lastname: Tariq
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois 61801, United States of America.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Trindade da Rosa
authors.affiliation: University of Bonn, Bonn, NRW 53115, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Kesser
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois 61801, United States of America.
authors.forename: Zeeshan
authors.initials: Z
authors.lastname: Iqbal
authors.affiliation: National Autonomous University of Mexico, Querétaro, Querétaro 76230, Mexico.
authors.forename: Ofelia
authors.initials: O
authors.lastname: Mora
authors.affiliation: University of Bonn, Bonn, NRW 53115, Germany.
authors.forename: Helga
authors.initials: H
authors.lastname: Sauerwein
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois 61801, United States of America.
authors.forename: James K
authors.initials: JK
authors.lastname: Drackley
authors.affiliation: Istituto di Zootecnica, Facoltà di Scienze Agrarie Alimentari ed Ambientali, Università Cattolica del Sacro Cuore, Piacenza 29122, Italy.
authors.forename: Erminio
authors.initials: E
authors.lastname: Trevisi
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois 61801, United States of America.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Loor
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000273:Adipose Tissue / Q000378:metabolism*; D050154:Adiposity / Q000187:drug effects; D000821:Animal Feed; D000818:Animals; D001706:Biopsy; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D001835:Body Weight; D002417:Cattle; D004032:Diet / Q000662:veterinary*; D002149:Energy Intake / Q000502:physiology*; D005227:Fatty Acids / Q000097:blood; D005260:Female; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000097:blood / Q000378:metabolism; D007333:Insulin Resistance; D018482:Muscle, Skeletal / Q000378:metabolism*; D047495:PPAR gamma / Q000378:metabolism; D016133:Polymerase Chain Reaction; D045162:Thiazolidinediones / Q000737:chemistry*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D005227:Fatty Acids; D007004:Hypoglycemic Agents; D007328:Insulin; D047495:PPAR gamma; D045162:Thiazolidinediones; D014280:Triglycerides; C089946:2,4-thiazolidinedione; D020155:3-Hydroxybutyric Acid