A Mouse Model of Metabolic Syndrome: Insulin Resistance, Fatty Liver and Non-Alcoholic Fatty Pancreas Disease (NAFPD) in C57BL/6 Mice Fed a High Fat Diet

Diet-induced obesity in C57BL/6 mice triggers common features of human metabolic syndrome (MetS). The purpose is to assess the suitability of a diet-induced obesity model for investigating non-alcoholic fatty pancreatic disease (NAFPD), fatty liver and insulin resistance. Adult C57BL/6 mice were fed either high-fat chow (HFC, 60% fat) or standard chow (SC, 10% fat) during a 16-week period. We evaluated in both groups: hepatopancreatic injuries, pancreatic islets size, alpha and beta-cell immunodensities, intraperitoneal insulin tolerance test (IPITT) and oral glucose tolerance test (OGTT). The HFC mice displayed greater mass gain (p<0.0001) and total visceral fat pads (p<0.001). OGTT showed impairment of glucose clearance in HFC mice (p<0.0001). IPITT revealed insulin resistance in HFC mice (p<0.0001). The HFC mice showed larger pancreatic islet size and significantly greater alpha and beta-cell immunodensities than SC mice. Pancreas and liver from HFC were heavier and contained higher fat concentration. In conclusion, C57BL/6 mice fed a high-fat diet develop features of NAFPD. Insulin resistance and ectopic accumulation of hepatic fat are well known to occur in MetS. Additionally, the importance of fat accumulation in the pancreas has been recently highlighted. Therefore, this model could help to elucidate target organ alterations associated with metabolic syndrome

Stereological tools in biomedical research

Stereological studies are more and more frequent in literature, particularly in the development/evolution, pathology, and neurosciences areas. The stereology challenge is to understand the structural inner threedimensional arrangement based on the analysis of the structure slices only showing two-dimensional information. Cavalieri and Scherle's methods to estimate volume, and Buffon's needle problem, are commented in the stereological context. A group of actions is needed to appropriately quantify morphological structures (unbiased and reproducibly), e.g. sampling, isotropic and uniform randomly sections (Delesse's principle), and updated stereological tools (disector, fractionator, nucleator, etc). Through the correct stereology use, a quantitative study with little effort could be performed: efficiency in stereology means a minimum slices sample counting (little work), low cost (slices preparation), but good accuracy. In the present text, a short review of the main stereological tools is done as a background basis to non-expert scientists

Pancreatic islet (of Langerhans) revisited

One hundred and fifty years ago, Paul Langerhans described what would come to be known as pancreatic ‘islet of Langerhans’. Since then, we have accumulated knowledge about the pancreatic islet, the cells that exist there and the hormones secreted by these cells. The increasing prevalence of obesity, diabetes and Alzheimer’s disease in the population (three conditions that are linked to pancreatic islet function), the islet has been playing a significant role in endocrinological and metabolic studies searching how we can protect the pancreatic islet and its cell content, or how we can regenerate it. This review will be interested in the most recent and relevant aspects of knowledge regarding the pancreatic islet, always mentioning the evolution of knowledge and future perspectives for the treatment of diabetes and Alzheimer’s disease. The most recent research with microRNAs and islet culture and pseudoislet culture (organoids) allows predicting advances in knowledge with new drugs to act on the islet/cells (such as the hormone glucagon-like peptide (GLP) -1) as well as induction of other islet cells like alpha-cells and delta-cells to transform into beta-cells

Effect of telmisartan on preexistent cardiac and renal lesions in spontaneously hypertensive mature rats

Fifteen adult male spontaneously hypertensive rats (one year old) (SHR) were separated into three groups (n=5 each) during 15 weeks as follows: initial control group (IC); final control group (FC); and telmisartan group (T) (1.2 mg/kg/day of telmisartan). Serum and urinary creatinine and proteinuria were not different comparing untreated and telmisartan-treated SHRs. FC rats showed a continuous BP increase during the study while T rats reached the 15th week with a significantly low BP. The LV mass index was significantly smaller in the T group than in the FC group, as was the glomerular hypertrophy. The cardiomyocyte nuclei density per area and the cardiomyocyte mean cross-sectional area were smaller in the T group than in both the IC and FC groups. Intramyocardial artery densities (per area and per volume) were greater in the T group than in untreated SHRs, but myocardial fibrosis was reduced. In conclusion, telmisartan monotherapy effects on BP and also on the hypertension target organs, heart and kidney, are favorable. Telmisartan is able to attenuate SHR cardiomyocyte and glomerular hypertrophies, and myocardial reactive fibrosis as well. It also is favorable to the intramyocardial microcirculation

Glomerular profile numerical density per area and mean glomerular volume in rats submitted to nitric oxide synthase blockade

Rats submitted to chronic inhibition of nitric oxide synthase (NOS) have developed systemic hypertension and consequent renal injury. The present study aims to determine glomerular quantitative changes due to NOS inhibition in rats. Adults and normotensive Wistar rats were separated into control and L-NAME groups (each group n=10). The animals received water and food ad libitum, while L-NAME rats received N ~ - Nitro-L-Arginine methyl Ester hydrochloride to inhibit NOS (50mg/kg/day) in drinking water during 40 days. After that period the rats were sacrificed, the kidneys were removed, measured, and prepared for histological and stereological analyses. The glomerular density per area [NA(giom)] and the mean glomerular volume [Y] were determined per animal in 15 random fields. In LNAME rat the blood pressure was 76% higher than the respective control group with the same age. Glomeruli had global or segmental glomerular sclerosis; some glomeruli only presented an atrophic structure. The renal volume was not different between control and L-NAME rats (p>0.05). However, L-NAME rats had the NA(giom) 33% smaller than the control rats (p=0.0001) and, concomitantly, L-NAME rats had the Y (glom) 33% higher than the control ones (p=0.004). These results demonstrate morphological renal alterations caused by NOS inhibition and hypertension

Papel da óxido nítrico sintase na etiopatogenia da estenose hipertrófica do piloro na infância

OBJETIVOS: reproduzir, experimentalmente, em ratos, por meio do inibidor da enzima óxido nítrico sintase (ONS - L-NAME), os achados histopatológicos correspondentes a estenose hipertrófica do piloro da infância (EHPI). MÉTODOS: para reproduzir o modelo de inibição de ONS na produção de EHPI, administrou-se L-NAME em ratas grávidas, a partir do 14º dia gestacional (grupo L-NAME), comparando-se com uma gestação de controle. Após o nascimento, todos os ratos do grupo L-NAME foram mantidos sob inibição da ONS até o 42º dia de vida, quando foram sacrificados. Os filhotes da gestação de controle, em que nenhuma droga foi administrada, foram também sacrificados com 42 dias de vida. Os animais e as vísceras foram analisados e pesados. A região pilórica foi preparada tecnicamente e observada em microscopia de luz. RESULTADOS: em comparação com os animais de controle, os L-NAME tiveram peso corporal e intestinal menor e peso gástrico maior. Nos animais L-NAME a microscopia de luz evidenciou hipertrofia da camada circular do músculo liso do piloro. CONCLUSÃO: este trabalho reproduziu um modelo experimental de estudo da estenose hipertrófica do piloro e comprovou, neste modelo, a associação da ausência da ON sintase na musculatura do piloro

Effect of unilateral nephrectomy on renal function of diabetic rats

Glomerular alterations of experimental diabetes mellitus are observed in animals submitted to a reduction in renal mass, suggesting that some mechanisms responsible for the progression of renal disease are common. The aim of this study was to investigate the effect of nephrectomy on the renal function and morphology of diabetic rats. Male Wistar rats were divided into 4 groups: control (C), n=8; diabetic (DM), n=8; non-diabetic nephrectomized (Nx), n=8; (DMNx), n=9. DM was induced by streptozotocin (65mg/Kg), and animals were treated with insulin. After 12 weeks, the glomerular filtration rate (GFR), renal plasma flow (RPF) and mean arterial pressure (MAP) were evaluated in unanaesthetized animals. Glomerular volume (GV), glomerular sclerosis index (GSI), mesangial volume density (Vvmes) and glomerular capillary surface density (Svcap) were also evaluated. Results show that kidney weight increased in Nx groups, being higher in DMNx. GFR was higher in Nx groups as was RPF, being higher in DMNx. RVR was lower in Nx groups, especially in DMNx. MAP was not different among the groups. RPF and GFR showed a high correlation for the DMNx group (r=0.95, p=0.02). The DMNx group showed a correlation between RVR and GFR (r=-0.96, p=0.005). The GV increased in Nx groups, and the GSI was higher in DMNx. Vvmes and Svcap increased in DMNx group. In summary, Nx groups developed similar degrees of glomerular hypertrophy, but only DMNx showed an increased value for GSI. The present data suggest that the acceleration of glomerular lesions in DMNx animals was more closely associated to hemodynamic adaptations than to glomerular hypertrophy