ABSTRACT
The eSMT rat is a new spontaneous model of type 2 diabetes that develops a progressive diabetic syndrome with a stronger incidence in males than in females. We decide to investigate the progression of the pancreatic histopathological changes during the lifespan of the eSMT rat, especially those associated with islet cell populations. Besides that, some plasmatic parameters were evaluated in order to correlate them with the morphological findings. Male eSMT and Sprague-Dawley control rats were used. The results showed a dramatic decrease of the volume density (VD) of endocrine tissue in the eSMT rats without evidence of insulitis. Islets became fragmented structures with strong presence of interstitial fibrosis. Consequently, plasma insulin levels showed a significant decrease, while plasma glucose, cholesterol and triglyceride levels were increased. Normal rats showed no significant changes in the VD of endocrine tissue, except for the older animals, where the VD of ß-cell population was increased. Early derangements observed in islets, together with the progressive decrease of endocrine tissue and the metabolic disorders described, would be responsible for an irreversible pathologic condition which avoids the animal survival beyond about 18 months of age. However, there is still a need to investigate the causes of endocrine tissue decrease and its possible association with an inflammatory process that it could be associated with the development and progression of fibrosis.
Subject(s)
Diabetes Mellitus, Type 2/pathology , Insulin-Secreting Cells/pathology , Pancreas/pathology , Age Factors , Animals , Blood Glucose/analysis , Cell Size , Cholesterol/blood , Diabetes Mellitus, Type 2/metabolism , Disease Models, Animal , Disease Progression , Endocrine Cells/metabolism , Fibrosis , Immunohistochemistry , Insulin/blood , Insulin-Secreting Cells/metabolism , Islets of Langerhans/metabolism , Islets of Langerhans/pathology , Male , Pancreas/metabolism , Rats , Rats, Sprague-Dawley , Rats, Wistar , Thiobarbituric Acid Reactive Substances/metabolism , Triglycerides/bloodABSTRACT
Although the endocrine pancreas is the purpose of several deep investigations, morphological data referred to the effect of aging on the gland are not homogeneous. The purpose of the current work was to analyze the changes occurring in the pancreas of aged rats, with especial reference to the islet cell populations. Six young (Y), old (O) and senescent (S) male Sprague-Dawley rats were used. The pancreas tails were processed for light microscopy and studied by means of routine stains as well as by immunohistochemical identification of insulin-, glucagon-, somatostatin-, and pancreatic polypeptide- secreting cells (Dako Envision System, DAB as chromogen). A progressive pancreatic histoarchitecture distortion was found among the aged animals. Even when the alterations were not uniformly observed, they appeared more evident and severe in the S group. The S rats showed significantly increased volume density and cell density of the B cell population, as well as larger number of islet profiles, when compared to O rats. A significant progressive increment of adipose tissue was also evident in aged animals. No abnormal changes were detected in the non-B cell populations of the different groups. The quantitative changes found in aged animals suggest a possible compensatory reaction of the B cell population in an attempt to curb the influence of diabetogenic factors mounting with advanced age.
Subject(s)
Aging/physiology , Islets of Langerhans/cytology , Islets of Langerhans/physiology , Pancreas/cytology , Pancreas/physiology , Animals , Immunohistochemistry , Male , Rats , Rats, Sprague-DawleyABSTRACT
Although the endocrine pancreas is the purpose of several deep investigations, morphological data referred to the effect of aging on the gland are not homogeneous. The purpose of the current work was to analyze the changes occurring in the pancreas of aged rats, with especial reference to the islet cell populations. Six young (Y), old (O) and senescent (S) male Sprague-Dawley rats were used. The pancreas tails were processed for light microscopy and studied by means of routine stains as well as by immunohistochemical identification of insulin-, glucagon-, somatostatin-, and pancreatic polypeptide- secreting cells (Dako Envision System, DAB as chromogen). A progressive pancreatic histoarchitecture distortion was found among the aged animals. Even when the alterations were not uniformly observed, they appeared more evident and severe in the S group. The S rats showed significantly increased volume density and cell density of the B cell population, as well as larger number of islet profiles, when compared to O rats. A significant progressive increment of adipose tissue was also evident in aged animals. No abnormal changes were detected in the non.B cell populations of the different groups. (AU)
Subject(s)
Male , Comparative Study , Animals , Rats , Aging/physiology , Islets of Langerhans/cytology , Islets of Langerhans/physiology , Pancreas/cytology , Pancreas/physiology , Immunohistochemistry , Rats, Sprague-DawleyABSTRACT
Although the endocrine pancreas is the purpose of several deep investigations, morphological data referred to the effect of aging on the gland are not homogeneous. The purpose of the current work was to analyze the changes occurring in the pancreas of aged rats, with especial reference to the islet cell populations. Six young (Y), old (O) and senescent (S) male Sprague-Dawley rats were used. The pancreas tails were processed for light microscopy and studied by means of routine stains as well as by immunohistochemical identification of insulin-, glucagon-, somatostatin-, and pancreatic polypeptide- secreting cells (Dako Envision System, DAB as chromogen). A progressive pancreatic histoarchitecture distortion was found among the aged animals. Even when the alterations were not uniformly observed, they appeared more evident and severe in the S group. The S rats showed significantly increased volume density and cell density of the B cell population, as well as larger number of islet profiles, when compared to O rats. A significant progressive increment of adipose tissue was also evident in aged animals. No abnormal changes were detected in the non.B cell populations of the different groups.
Subject(s)
Male , Animals , Rats , Aging/physiology , Islets of Langerhans/cytology , Islets of Langerhans/physiology , Pancreas/cytology , Pancreas/physiology , Immunohistochemistry , Rats, Sprague-DawleyABSTRACT
Although the endocrine pancreas is the purpose of several deep investigations, morphological data referred to the effect of aging on the gland are not homogeneous. The purpose of the current work was to analyze the changes occurring in the pancreas of aged rats, with especial reference to the islet cell populations. Six young (Y), old (O) and senescent (S) male Sprague-Dawley rats were used. The pancreas tails were processed for light microscopy and studied by means of routine stains as well as by immunohistochemical identification of insulin-, glucagon-, somatostatin-, and pancreatic polypeptide- secreting cells (Dako Envision System, DAB as chromogen). A progressive pancreatic histoarchitecture distortion was found among the aged animals. Even when the alterations were not uniformly observed, they appeared more evident and severe in the S group. The S rats showed significantly increased volume density and cell density of the B cell population, as well as larger number of islet profiles, when compared to O rats. A significant progressive increment of adipose tissue was also evident in aged animals. No abnormal changes were detected in the non-B cell populations of the different groups. The quantitative changes found in aged animals suggest a possible compensatory reaction of the B cell population in an attempt to curb the influence of diabetogenic factors mounting with advanced age.
