ABSTRACT
Hepatic responsiveness to gluconeogenic substrates during insulin-induced hypoglycemia was investigated. For this purpose, livers were perfused with a saturating concentration of 2 mM glycerol, 5 mM L-alanine or 5 mM L-glutamine as gluconeogenic substrates. All experiments were performed 1 h after an ip injection of saline (CN group) or 1 IU/kg of insulin (IN group). The IN group showed higher (P<0.05) hepatic glucose production from glycerol, L-alanine and L-glutamine and higher (P<0.05) production of L-lactate, pyruvate and urea from L-alanine and L-glutamine. In addition, ip injection of 100 mg/kg glycerol, L-alanine and L-glutamine promoted glucose recovery. The results indicate that the hepatic capacity to produce glucose from gluconeogenic precursors was increased during insulin-induced hypoglycemia.
Subject(s)
Animals , Male , Rats , Gluconeogenesis , Hypoglycemia/metabolism , Liver/metabolism , Alanine/blood , Alanine/pharmacology , Blood Glucose/analysis , Cryoprotective Agents/pharmacology , Gluconeogenesis/drug effects , Glucose/biosynthesis , Glutamine/blood , Glutamine/pharmacology , Glycerol/blood , Glycerol/pharmacology , Hypoglycemia/chemically induced , Insulin/adverse effects , Lactic Acid/biosynthesis , Liver/drug effects , Pyruvic Acid/metabolism , Rats, Wistar , Urea/metabolismABSTRACT
A leptina e uma proteina produzida e secretada pelo tecido adiposo, que possui efeito supressor da ingestao alimentar agindo no hipotalamo. Recentemente, alguns autores demostraram efeitos perifericos da leptina e formularam a hipotese desta funcionar tambem como hormonio contra regulador da insulina...
Subject(s)
Animals , Male , Rats , Blood Glucose/metabolism , Adipocytes/drug effects , Muscle, Skeletal/metabolism , Adipose Tissue/metabolism , Rats, WistarABSTRACT
The OB protein, also known as leptin, is secreted by adipose tissue, circulates in the blood, probably bound to a family of binding proteins, and acts on central neural networks regulating ingestive behavior and energy balance. The two forms of leptin receptors (long and short forms) have been identified in various peripheral tissues, a fact that makes them possible target sites for a direct action of leptin. It has been shown that the OB protein interferes with insulin secretion from pancreatic islets, reduces insulin-stimulated glucose transport in adipocytes, and increases glucose transport, glycogen synthesis and fatty acid oxidation in skeletal muscle. Under normoglycemic and normoinsulinemic conditions, leptin seems to shift the flux of metabolites from adipose tissue to skeletal muscle. This may function as a peripheral mechanism that helps control body weight and prevents obesity. Data that substantiate this hypothesis are presented in this review