Modulação do mecanismo de sedreção de insulina em ilhotas pancreaticas de ratos submetidos a restrição protetica e suplementados com taurina / Insulin secretion mechanisms in pancreatic islets of protein-restricted rats supplemented with taurine

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Malnutrition still is a public health issue, especially in developing countries. Many studies correlate malnourishment during early life and the development of cardiovascular disease and type 2 Diabetes Mellitus on latter stages. Animal models of malnutrition reveal impaired insulin secretion stimulated by glucose and other insulinotropic agents as well as lower expression of key proteins for b cell function. The literature shows that taurine supplementation increases insulin secretion and regulates calcium dynamics on b cells. Male, 21 days old, wistar rats received diet containing 17% (C) or 6% (D) of protein. Both groups received taurine supplementation on the drinking water for 30 (CT 30 and DT 30) and 90 (CT90 and DT 30) days. Next we assessed biometric and biochemical parameters, glucose tolerance, glucose and carbacholstimulated insulin secretion, protein expression of muscarinic M3 receptor, Phospholipase C b2, SERCA3, Syntaxin 1 and, finally, we registered cytoplasmic Ca2+ after stimulus with glucose and carbachol. Protein restricted rats showed lower body weight, plasma proteins (C = 6,81±0,04; CT30 = 7,15±0,54; CT90 = 6,87±0,19; D = 5,35±0,24; DT30 = 5,37±0,28; DT90 = 5,70±0,09 g/dl; n = 3-5), albumin (C = 3,20±0,11; CT30 = 3,41±0,02; CT90 = 3,18±0,05; D = 2,74±0,07; DT30 = 2,49±0,09; DT90 = 2,67±0,04 g/dl; n = 5-9) and increased glucose tolerance (C = 30249±2682; CT30 = 37255±6691; CT90 = 29365±2257; D = 16916±1609; DT30 = 18791±2859; DT90 = 23425±3856 AUC; n = 5-9). Taurine supplementation had no effect upon nutritional status parameters and partially restored glucose tolerance and insulinemia to C levels. Taurine increased secretory response to glucose and carbachol (C = 9,4+0,8; CT90 = 12,4+0,7; D = 6,4+0,5; DT90 = 9+0,7 ng/ml; n = 12). It also increased protein expression of M3 receptor (C = 100+24; CT90 = 155+80; D = 51+10; DT90 = 108+14 % of C; n = 5), SERCA 3 (C = 100+21; CT90 = 174+17; D =96+90; DT90 = 149+11 % of C; n = 6) and syntaxin 1 (C = 100+30; CT90 = 92+40; D = 50+12; DT90 = 77+11 % of C; n = 5). Finally, taurine supplementation for 90 days improved Ca2+ dynamics when the islets were stimulated with glucose. In conclusion, these data show that taurine supplementation restores secretory responsiveness to glucose and carbachol possibly through Ca2+ dynamics modulation and increased expression of key proteins for insulin secretion.

ASSUNTO(S)

desnutrição taurina dieta com restrição de proteinas protein-restricted diet taurine islands of langerhans insulina - secreção langerhans insulin ilhotas de malnutrition

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