Effect of long-term treatment with insulin and/or acarbose on glomerular basement membrane thickening in alloxan-diabetic rats

Acarbose is a competitive inhibitor of the intestinal alpha-glycosidases, that can delay absorption of intestinal carbohydrates causing their malabsorption. In the present paper we studied the effects of insulin, acarbose and their association on glomerular basement membrane thickening in alloxan-diabetic rats. Twenty-five male and female Wistar rats, approximately 3 months old at the beginning of the experiment, were assigned randomly to each of five experimental groups: normal control rats, alloxan-diabetic control rats, alloxan-diabetic rats treated with acarbose, alloxan-diabetic rats treated with insulin, and aloxan-diabetic rats treated with insulin plus acarbose. Alloxan was administered in a single iv dose of 42 mg/kg body weight. Insulin was given subcutaneously at doses of 18 to 30 IU/kg corrected daily on the basis of glycosuria and ketonuria. Acarbose was given mixed with rat chow in a dose of 50 mg/100 g chow. Body weight, water and food intake and diuresis, as well as blood and urine glucose were determined after 1, 3, 6, 9, and 12 months of treatment. Glomerular basement membrane (GBM) thickening was determined by electron microscopy at the same times. Clear clinical and laboratory signs of severe diabetes, with blood glucose levels above 200 mg/dl and urine glucose above 3000 mg/dl, were observed in all alloxan-diabetic control rats, in all periods of follow-up, whereas administration of insulin or acarbose reduced the blood glucose levels of treated groups. The most satisfactory control of blood and urine glucose was observed in animals treated with both insulin and acarbose. However, diarrhea was observed in diabetic rats treated with acarbose associated or not with insulin, GBM thickening was correlated with age in all groups. Beginning at six months after diabetes induction, the GBM of untreated diabetic rats was significantly thicker (mean + 4.446 + 0.45 mm) than that of normal rats (2.977 + 0.63 mm). Both insulin and acarbose prevented GBM thickening and their combination induced thickening similar to the age-dependent thickening observed for normal rats of the same age. We conclude that acarbose when combined with insulin may be a good option in the control of diabetes and its renal complications.

Effect of pancreas transplantation on the prevention of nephropathy in alloxan-induced diabetic rats

We studied the effects of pancreas transplantation on kidney lesions of rats with alloxan-induced diabetes. Ninety inbred male Lewis rats were randomly assigned to 3 experimental groups: group NC included 30 non-diabetic control rats, group DC included 30 alloxan-induced diabetic control rats, and group PT include 30 alloxan-induced diabetic rats that received pancreas transplants from normal donor Lewis rats. Each group was further divided into 3 subgroups of 10 rats which were sacrificed at 1,3, and 6 months of follow-up, respectively. Clinical and laboratory parameters during these periods were documented. The kidneys of 5 rats in each subgroup were studied and 50 glomeruli and tubules from each kidney were analyzed by light microscopy by two different investigators in a double-blind study. There was progressive glomerular basement membrane thickening (GBMT), mesangial enlargement (ME), and Bowman's capsule thickening (BCT) in kidneys of rats in the 3 experimental groups during follow-up. These alterations were significantly higher in DC rats (GBMT: 1.99 ñ 0.31; ME: 2.00 ñ 0.33; BCT: 1.88 ñ 0.27) when compared to NC (GBMT: 1.54 ñ 0.30; ME: 1.56 ñ 0.47; BCT: 1.36 ñ 0.35) and PT rats (GBMT: 1.49 ñ 0.29; ME: 1.57 ñ 0.36; BCT: 1.35 ñ 0.28) at 6 months (P<0,01). The extent of GBMT, ME, and BCT observed in DC rats at 1 and 3 months was not significantly different from NC and PT rats. The amount of kidney lesions in PT rats was similar to that of NC rats and lower than those of DC rats at 6 months (P<0.01). In addition, Armanni-Ebstein lesions of the tubules (AE) and tubular lumen protein (PRO) observed in DC rats were not present in NC or PT rats. We conclude that pancreas transplantation in alloxan-induced diabetic rats prevents the development of kidney lesions beginning at 6 months after transplantation.

Müller cells and diabetic retinopathy

Müller cells provide nutrition for neural cells. We studied the structure and ultrastructure of Müller cells in the retina of thirty 3-month old Wistar rats, divided equally into 3 groups: normal rats, alloxan diabetic rats and treated alloxan diabetic rats, 1 and 12 months after induction of diabetes. We observed that the Müller cell nuclei under light microscope examination had hexagonal shape and higher density than the other nuclei. Differences between groups could be observed only by electron microscopy. In the diabetic rats, Müller cells presented dispersion of nuclear chromatin and electrondense nuclear granulations, with the presence of increased glycogen, dense bodies and lysosomes in the cytoplasm. The alterations were more frequent in the perivascular region and at 12 months. The treated diabetic rats exhibited some alterations we observed in diabetic rats, but these alterations were less intense. We conclude that, despite the treatment, the diabetic retinopathy continues to evolve

Effects of cyclosporin A immunosuppression on pancreaticoduodenal transplantation in alloxan-diabetic rats

1. Forty-five outbred Wistar rats were randomly assigned to three experimental groups: GI, 10 non-diabetic control rats; GII, 10 alloxan-diabetic control rats; GIII, 25 alloxan-diabetic rats which received pancreaticoduodenal transplantation (PDT) from normal Wistar donor rats and were immunosuppressed with cyclosporin A (Cy-A), 10 mg kg body weight-1 day-1, administered intraperitoneally for 30 days. 2. In parallel, 15 alloxan-diabetic inbred Wistar rats received isogeneic PDT from normal Wistar donor rats. 3. Cy-A prevented graft rejection in the 15 surviving animals in group III. These observations were confirmed by clinical and biochemical parameters (body weight, urine output, water and food intake, blood and urinary glucose and plasma insulin) and by histology and immunohistochemistry of the pancreas. 4. However, Cy-A was associated with 60% of the infectious complications in transplanted rats leading to 40% mortality. Pulmonary infections were the main cause of death. There were no side effects of immunosuppression on the pancreas. Infections were not significant in inbred rats submitted to PDT

Insuficiencia hepatica aguda no cobaio. Modelo experimental causado pela injecao de oleato de monoetanolamina. / Acute hepatic insufficiency in guinea pigs. Experimental model caused by monoethanolamina oleate injection

Com o objetivo de produzir um modelo experimental de insuficiencia hepatica aguda (IHA) no cobaio, foram empregados 60 cobaios distribuidos nos seguintes grupos experimentais: a) Grupo Etanolamina - 42 animais submetidos a injecao de 2,5 ml de oleato de monoetanolamina no ducto biliar comun; b) Grupo Controle - 18 animais, nos quais foram injetados 2,5 ml de solucao de NaCI a 0,9% no ducto biliar comum. Foram utilizados para a caracterizacao da IHA os seguintes parametros: quadro clinico, exames laboratoriais (bioquimicos, hematologicos e teste de coagulacao sanguinea) e exame anatomopatologico. A injecao de etanolamina produziu um modelo de insuficiencia hepatica aguda, com a ocorrencia de coma hepatico bem definido em 85,5% dos cobaios nas primeiras 96 horas de evolucao A IHA foi caracterizada pelo quadro clinico tipico de falencia hepatica, alteracoes dos exames bioquimicos (elevacao das bilirrubinas, transaminases e fosfatase alcalina), pelos disturbios da coagulacao sanguinea (alongamento dos tempos de protrombina e tromboplastina parcial ativada e queda do fibrinogenio plasmatico) e pela necrose hepatica macica constatada no exame anatomopatolofico.O modelo experimental desenvolvido pode ser util para o estudo da fisiopatologia da insuficiencia hepatica e para a pesquisa de novos metodos terapeuticos do coma hepatico

Um novo modelo experimental de insuficiencia hepatica aguda. / A new experimental model of acute hepatic insufficiency

E apresentado um novo modelo de insuficiencia hepatica aguda no cobaio, produzido pela injecao intrabiliar de solucao esclerosante. Foram empregados 100 cobaios distribuidos em dois grupos experimentais: 1) Grupo Solucao Esclerosante - 70 animais submetidos a injecao no ducto biliar comum de uma solucao constituida por fenol, acido acetico glacial, glicerina e agua bidestilada na dose de 1 ml. 2) Grupo Controle - 30 animais, noa quais foram injetados 1 ml de solucao de NaCl a 0,9%.A injecao da solucao esclerosante no ducto biliar produziu em 52,9% dos cobaios insuficiencia hepatica aguda caracterizada por: a) quadro clinico bem definido, com evolucao para o coma hepatico de instalacao lenta e longa duracao: b) alteracao dos exames bioquimicos e dos testes de coagulacao sanguinea; c) alteracoes anatomo-patologicas. O modelo experimental desenvolvido pode ser util para o estudo dos mecanismos fisiopatologicos envolvidos na insuficiencia hepatocelular e para a avaliacao de novos metodos para o tratamento do coma hepatico