Metabolic and Hormonal Profile of overnourished sheep submited to Hyperketonemia and hyperlipidemia, and treated with recombinat bovine somatotropin

Author(s)

Carolina Akiko Sato Cabral de Araujo

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2014-09-16

Examining board members

Enrico Lippi Ortolani; Alexandre Coutinho Antonelli; Marta Lizandra do Rêgo Leal; Alice Maria Melville Paiva Della Libera; Maria Claudia Araripe Sucupira

• Advisor: Enrico Lippi Ortolani

Abstract

The aim of this study was to clarify the biochemical and hormonal mechanisms of action of recombinant bovine somatotropin (r-bST), recommended in the treatment of pregnancy toxemia (PT). Two experiments were conducted inducing hyperlipidemia or hyperketonemia in 39 high body condition sheep pretreated or no with 160 mg of a commercial product of rbST subcutaneously. The hyperketonemia was caused by IV infusion of 5 mM / kg BW of beta-hydroxybutyrate (BHB) during two hours and hyperlipidemia with IV injection of a 20% fish oil solution corresponding to 0.54 g of triglyceride / kg BW in four days course. These infusions successfully caused the expected effects. In the first experiment, treatment with rbST caused a significant increase of gluconeogenesis by converting BHB into glucose, higher levels of insulin, with consequent increased insulin resistance, increase in the concentration of IGF1 leading to mobilization of urea nitrogen for deposits and increased activity of GGT. In the second experiment, the r-bST greatly increased gluconeogenesis generated by metabolism of non esterified fatty acids (NEFA), BHB and glucose, with emphasis on NEFA, elevated levels of insulin and the percentage of insulin resistance, and increased activity of AST and GGT and bilirrubin direct and total. In conclusion, the pharmacological action of r-bST is based on vigorous increase capacity on gluconeogenesis, concomitantly reducing the adverse catabolites (NEFA and BHB) in the PT process. An additional experiment was performed to compare the diagnostic capability of detecting BHB in whole blood, between the enzymatic diagnostic kit (Randox®), considered gold standard, and commercial test strips (Precision Xceed®) read in hand-held meter. 247 sheep blood samples were obtained in the first experiment in which BHB solution had been infused. Two ketonemic tracks were considered: 0.7 to 1.5 mM characterized as unapparent ketosis and above this value as a clinical ketosis. The correlation between the methods was high (r = 0.98, P <0.001). In test strips method, ketosis unapparent showed sensitivity of 0.97 and specificity of 0.89 and in ketosis apparent sensitivity of 0.99 and specificity of 0.75, respectively. The test strips can be used efficiently in the early diagnosis of cases of TP, with fast reading and low cost. (AU)

• FAPESP's process: 11/21923-4 - Metabolic profile of ewes submitted to hipertryacilglyceremia and treated with recombinant bovine somatotropin (r-bST)
• Grantee: Carolina Akiko Sato Cabral de Araújo
• Support Opportunities: Scholarships in Brazil - Doctorate