Effect of Black Tea on Histological and Immunohistochemical Changes in Pancreatic Tissues of Normal and Streptozotocin-induced Diabetic Mice (Mus musculus)

The aim of the present study is to evaluate the effect of hot water extract of black tea in regenerating P cells in streptozotocin-induced diabetic mice. Light microscopic examination of pancreatic sections of streptozotocin-induced diabetic mice showed the acinar cells to be small, shrunken, and with deteriorated P cells. The dose of streptozotocin not only altered the function of P cells but also damaged the acinar region. The changes in acinar cells were coarsening of endoplasmic reticulation suggesting alteration in their secretory function. The control pancreatic tissue showed well-defined granulated islets and dark P cells when stained with chrome hematoxylin and phloxine. Interestingly, pancreatic sections of diabetic mice fed with black-tea extract showed regeneration of P cells and acinar region appeared normal with increased numbers of P cells. To understand the probable mechanism of action of black-tea extract, we analyzed inducible nitric oxide synthase (iNOS) expression by immunohistochemistry and the results showed an increased iNOS levels in streptozotocin-induced diabetic pancreas, and such high iNOS levels were inhibited in black-tea extract treated mice. According to histological results obtained, it can be concluded that the black-tea extract helps in regeneration of damaged pancreas and protects pancreatic P cells by its antioxidant action against nitrosative stress in streptozotocin-induced diabetes. Microsc. Res. Tech. 72:723-726, 2009. (C) 2009 Wiley-Liss, Inc.