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Type: Artigo de periódico
Title: Peroxisome Proliferator-activated Receptor Gamma Coactivator-1-dependent Uncoupling Protein-2 Expression In Pancreatic Islets Of Rats: A Novel Pathway For Neural Control Of Insulin Secretion.
Author: De Souza, C T
Gasparetti, A L
Pereira-da-Silva, M
Araújo, E P
Carvalheira, J B
Saad, M J A
Boschero, A C
Carneiro, E M
Velloso, L A
Abstract: Sympathetic inputs inhibit insulin secretion through alpha2-adrenergic receptors coupled with Gi protein. High adrenergic tonus generated by exposure of homeothermic animals to cold reduces insulin secretion. In this study we evaluate the participation of UCP-2 in cold-induced regulation of insulin secretion. Static insulin secretion studies, western blotting and immunohistochemistry were used in this investigation. Exposure of rats to cold during 8 days promoted 60% ( n=15, p<0.05) reduction of basal serum insulin levels concentration accompanied by reduction of the area under insulin curve during i.p. GTT (50%, n=15, p<0.05). Isolated islets from cold-exposed rats secreted 57% ( n=6, p<0.05) less insulin following a glucose challenge. Previous sympathectomy, partially prevented the effect of cold exposure upon insulin secretion. Islets isolated from cold-exposed rats expressed 51% ( n=6, p<0.5) more UCP-2 than islets from control rats, while the inhibition of UCP-2 expression by antisense oligonucleotide treatment partially restored insulin secretion of islets obtained from cold-exposed rats. Cold exposure also induced an increase of 69% ( n=6, p<0.05) in PGC-1 protein content in pancreatic islets. Inhibition of islet PGC-1 expression by antisense oligonucleotide abrogated cold-induced UCP-2 expression and partially restored insulin secretion in islets exposed to cold. Our data indicate that sympathetic tonus generated by exposure of rats to cold induces the expression of PGC-1, which participates in the control of UCP-2 expression in pancreatic islets. Increased UCP-2 expression under these conditions could reduce the beta-cell ATP/ADP ratio and negatively regulate insulin secretion.
Subject: Acclimatization
Base Sequence
Blood Glucose
Cold Temperature
Dna Primers
Energy Metabolism
Gene Expression Regulation
In Vitro Techniques
Injections, Intravenous
Ion Channels
Islets Of Langerhans
Membrane Transport Proteins
Mitochondrial Proteins
Oligonucleotides, Antisense
Transcription Factors
Rights: fechado
Identifier DOI: 10.1007/s00125-003-1222-5
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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