Análise da expressão de proteínas da via de sinalização de insulina em próstata de ratos tratados com dexametasona
Carregando...
Data
2011-03-02
Autores
Costa, Maitê Megeto [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os glicocorticóides são amplamente utilizados na prática clínica como agentes antiinflamatórios e imunossupressores, e estão entre as drogas utilizadas nos tratamentos de cânceres, como o de próstata. Contudo, seu uso prolongado ou excessivo pode desencadear o diabetes mellitus tipo 2, caracterizado pela hiperglicemia devido à resistência periférica à insulina. Recente estudo do nosso grupo de pesquisa, utilizando modelo de diminuição da sensibilidade periférica à insulina pela administração de dexametasona (DEX, 1 mg/kg, ip) por 5 dias, demonstrou, na próstata ventral de ratos, atrofia epitelial e das células musculares lisas, além de alterações de elementos celulares do estroma prostático, como os fibroblastos. A partir deste estudo, inúmeras perguntas surgiram acerca dos mecanismos de sinalização presentes no tecido prostático neste modelo, especialmente em relação à insulina. Assim, neste trabalho investigamos as vias de sinalização da insulina e a proliferação celular epitelial na próstata ventral de ratos no modelo de resistência à insulina induzida pelo tratamento com dexametasona, buscando possível correlação com a expressão dos receptores de glicocorticóides (GR) e de andrógenos (AR). A resistência à insulina foi induzida em ratos Wistar machos adultos (n=4) pela administração de dexametasona (DEX, 1 mg/kg, ip), durante 5 dias, enquanto os ratos controles (CTL) receberam solução salina. O tratamento com a dexametasona resultou em diminuição significativa no peso corporal, mas não do peso prostático. Reduções na expressão das proteínas IRS-1/AKT/mTOR, constituintes da via de sinalização da insulina, e nos níveis das proteínas AR e GR foram observados nas próstatas de ratos resistentes à insulina, comparados com o grupo CTL.A frequência de células ARpositivas no epitélio acinar da próstata diminuiu no grupo tratado...
Glucocorticoids are widely used in clinical practice as anti-inflammatory and immunosuppressants agents, and are among the drugs used in treatment of cancers, such as the prostate. However, excessive or prolonged use can trigger diabetes mellitus type 2, characterized by hyperglycemia due to peripheral insulin resistance. Recent study of our research group, using model of decreased peripheral insulin sensitivity by administration of dexamethasone (DEX, 1 mg / kg, ip) for 5 days, showed, in rat ventral prostate, epithelial atrophy and of smooth muscle cells, in addition to alterations of cellular elements of the prostatic stroma, such as fibroblasts. From this study, many questions have arisen about the signaling mechanisms present in prostate tissue in this model, especially in relation to insulin. Thus, this study investigated the insulin signaling pathway and epithelial cell proliferation in the rat prostate in a model of insulin resistance induced by treatment with dexamethasone, searching for possible correlation with the expression of glucocorticoid (GR) and androgen (AR) receptors. Insulin resistance was induced in adult male Wistar rats (n=4) by the administration of dexamethasone (DEX, 1 mg/kg, ip) for 5 days, while the control (CTL) rats received saline. Dexamethasone treatment resulted in a significant decrease in body weight, but not of prostatic weight. Reductions in the expression of proteins IRS-1/AKT/mTOR, constituents of the signaling pathway of insulin, AR and GR levels protein were observed in the prostate of insulin resistant rats, compared with the CTL group. The frequency of ARpositive cells in the acinar epithelium of the prostate decreased in the group treated with DEX. Furthermore, the intensity of reaction for this receptor in the cell nuclei was lower in this group. The treatment with glucocorticoid reduced the frequency of PCNA-positive cells by 30-fold... (Complete abstract click electronic access below)
Glucocorticoids are widely used in clinical practice as anti-inflammatory and immunosuppressants agents, and are among the drugs used in treatment of cancers, such as the prostate. However, excessive or prolonged use can trigger diabetes mellitus type 2, characterized by hyperglycemia due to peripheral insulin resistance. Recent study of our research group, using model of decreased peripheral insulin sensitivity by administration of dexamethasone (DEX, 1 mg / kg, ip) for 5 days, showed, in rat ventral prostate, epithelial atrophy and of smooth muscle cells, in addition to alterations of cellular elements of the prostatic stroma, such as fibroblasts. From this study, many questions have arisen about the signaling mechanisms present in prostate tissue in this model, especially in relation to insulin. Thus, this study investigated the insulin signaling pathway and epithelial cell proliferation in the rat prostate in a model of insulin resistance induced by treatment with dexamethasone, searching for possible correlation with the expression of glucocorticoid (GR) and androgen (AR) receptors. Insulin resistance was induced in adult male Wistar rats (n=4) by the administration of dexamethasone (DEX, 1 mg/kg, ip) for 5 days, while the control (CTL) rats received saline. Dexamethasone treatment resulted in a significant decrease in body weight, but not of prostatic weight. Reductions in the expression of proteins IRS-1/AKT/mTOR, constituents of the signaling pathway of insulin, AR and GR levels protein were observed in the prostate of insulin resistant rats, compared with the CTL group. The frequency of ARpositive cells in the acinar epithelium of the prostate decreased in the group treated with DEX. Furthermore, the intensity of reaction for this receptor in the cell nuclei was lower in this group. The treatment with glucocorticoid reduced the frequency of PCNA-positive cells by 30-fold... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Próstata, Insulina, Resistência à insulina, Cell proliferation
Como citar
COSTA, Maitê Megeto. Análise da expressão de proteínas da via de sinalização de insulina em próstata de ratos tratados com dexametasona. 2011. 57 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2011.