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Type: Artigo de periódico
Title: Morphofunctional Alterations in Endocrine Pancreas of Short- and Long-term Dexamethasone-treated Rats
Author: Rafacho, A
Abrantes, JLF
Ribeiro, DL
Paula, FM
Pinto, ME
Boschero, AC
Bosqueiro, JR
Abstract: Long-term dexamethasone therapy may induce peripheral insulin resistance (IR), which in turn elicits increased beta-cell function and proliferation. However, whether such adaptive compensations occur during short-term treatment with dexamethasone is unclear. Here, we compared morphofunctional parameters in endocrine pancreas after short- and long-term dexamethasone administration. Groups of rats received daily i.p. injection of 1 mg/kg b.w. dexamethasone for 1 (DEX-1), 3 (DEX-3), or 5 consecutive days (DEX-5), whilst control rats were saline-treated (CTL). Despite the absence of apparent IR in DEX-1 rats, this group exhibited increased circulating insulin levels and glucose-stimulated insulin secretion (GSIS), compared to the CTL group (p < 0.05). Evident IR as well as marked hyperinsulinemia and GSIS, as judged by the static and dynamic insulin secretion values, were observed in DEX-3 and DEX-5 rats (p < 0.05). GSIS in islets cultured with 1 mu M dexamethasone was lower compared to the control (p < 0.05). Marked increases in beta-cell proliferation were observed in DEX-3 and DEX-5 rats, compared to CTL and DEX-1 rats (p < 0.05). The alterations observed in DEX-3 rats were more pronounced in DEX-5 rats, which also exhibited a higher content of islet Cdk4 and Cd2 proteins, compared to the CTL group (p < 0.05). We conclude that short-term dexamethasone treatment (DEX-1) induces an increase in beta-cell function that does not require the presence of discernible IR. As the treatment continues, the IR develops rapidly, and increased insulin secretion as well as beta-cell hyperplasia is demanded for the appropriate maintenance of glucose homeostasis.
Subject: beta-cell proliferation
insulin secretion
insulin resistance
short- and long-term treatment
Country: Alemanha
Editor: Georg Thieme Verlag Kg
Citation: Hormone And Metabolic Research. Georg Thieme Verlag Kg, v. 43, n. 4, n. 275, n. 281, 2011.
Rights: aberto
Identifier DOI: 10.1055/s-0030-1269896
Date Issue: 2011
Appears in Collections:Unicamp - Artigos e Outros Documentos

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