Dietary chia seed (Salvia hispanica L.) rich in a-linolenic acid improves adiposity and normalises hypertriacylglycerolaemia and insulin resistance in dyslipaemic rats

The present study investigates the benefits of the dietary intake of chia seed (Salvia hispanica L.) rich in α-linolenic acid and fibre upon dyslipidaemia and insulin resistance (IR), induced by intake of a sucrose-rich (62.5 %) diet (SRD). To achieve these goals two sets of experiments were designed: (i) to study the prevention of onset of dyslipidaemia and IR in Wistar rats fed during 3 weeks with a SRD in which chia seed was the dietary source of fat; (ii) to analyse the effectiveness of chia seed in improving or reversing the metabolic abnormalities described above. Rats were fed a SRD during 3 months; by the end of this period, stable dyslipidaemia and IR were present in the animals. From months 3-5, half the animals continued with the SRD and the other half were fed a SRD in which the source of fat was substituted by chia seed (SRD+chia). The control group received a diet in which sucrose was replaced by maize starch. The results showed that: (i) dietary chia seed prevented the onset of dyslipidaemia and IR in the rats fed the SRD for 3 weeks - glycaemia did not change; (ii) dyslipidaemia and IR in the long-term SRD-fed rats were normalised without changes in insulinaemia when chia seed provided the dietary fat during the last 2 months of the feeding period. Dietary chia seed reduced the visceral adiposity present in the SRD rats. The present study provides new data regarding the beneficial effect of chia seed upon lipid and glucose homeostasis in an experimental model of dislipidaemia and IR.Fil: Chicco, Adriana Graciela. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas; ArgentinaFil: D'alessandro, Maria Eugenia Guadalupe. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas; ArgentinaFil: Hein, Gustavo Juan. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas; ArgentinaFil: Oliva, Maria Eugenia. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas; ArgentinaFil: Lombardo, Yolanda B.. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas; Argentin

Dietary chia seed induced changes in hepatic transcription factors and their target lipogenic and oxidative enzyme activities in dyslipidaemic insulin-resistant rats

The present study analyses the effect of dietary chia seed rich in n-3 a-linolenic acid on the mechanisms underlying dyslipidaemia and liver steatosis developed in rats fed a sucrose-rich diet (SRD) for either 3 weeks or 5 months. The key hepatic enzyme activities such as fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), glucose-6-phosphate dehydrogenase (G-6-PDH), carnitine palmitoyltransferase-1 (CPT-1) and fatty acid oxidase (FAO) involved in lipid metabolism and the protein mass levels of sterol regulatory element-binding protein-1 (SREBP-1) and PPARa were studied. (1) For 3 weeks, Wistar rats were fed either a SRD with 11% of maize oil (MO) as dietary fat or a SRD in which chia seed replaced MO (SRD þ Chia). (2) A second group of rats were fed a SRD for 3 months. Afterwards, half the rats continued with the SRD while for the other half, MO was replaced by chia for 2 months (SRD þ Chia). In a control group, maize starch replaced sucrose. Liver TAG and the aforementioned parameters were analysed in all groups. The replacement of MO by chia in the SRD prevented (3 weeks) or improved/normalised (5 months) increases in dyslipidaemia, liver TAG, FAS, ACC and G-6-PDH activities, and increased FAO and CPT-1 activities. Protein levels of PPARa increased, and the increased mature form of SREBP-1 protein levels in the SRD was normalised by chia in both protocols (1 and 2). The present study provides new data regarding some key mechanisms related to the fate of hepatic fatty acid metabolism that seem to be involved in the effect of dietary chia seed in preventing and normalising/ improving dyslipidaemia and liver steatosis in an insulin-resistant rat model.Fil: Rossi, Andrea Silvana. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Cs.biologicas; ArgentinaFil: Oliva, Maria Eugenia. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Cs.biologicas; ArgentinaFil: Ferreira, María R.. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Cs.biologicas; ArgentinaFil: Chicco, Adriana Graciela. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Cs.biologicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; ArgentinaFil: Lombardo, Yolanda B.. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Cs.biologicas; Argentin

Effects of isolated soy protein on blood pressure and altered glucose metabolism in the heart muscle of dyslipemic insulin–resistant rats

El objetivo del trabajo fue analizar los efectos de la administración de proteína de soja aislada, sobre la hipertensión y alteraciones del metabolismo de la glucosa presentes en el músculo cardíaco de ratas dislipémicas insulino resistentes, inducidas por una ingesta crónica de una dieta rica en sacarosa (DRS). Ratas machos Wistar recibieron durante 4 meses DRS. Finalizado este período, la mitad de los animales continuó con la DRS y en la otra mitad la proteína de soja aislada sustituyó a la caseína como fuente proteica (DRS+PS) durante 4 meses adicionales. El grupo control (DC) consumió dieta control durante toda la experiencia. Los resultados alcanzados demuestran que ésta manipulación dietaría fue capaz de revertir la hipertensión arterial normalizando la alterada fosforilación de la glucosa estimada por la actividad hexoquinasa- y el contenido de glucosa-6-fosfato y glucógeno en el musculo cardiaco. La sustitución de caseína por proteína de soja como fuente proteica normalizó los niveles plasmáticos de triglicéridos, ácidos grasos no esterificados y la moderada hiperglucemia sin cambios en la insulinemia. La sensibilidad insulinica periférica global mejoró notablemente aunque sin alcanzar valores del grupo DC. Los resultados obtenidos muestran a la proteína de soja dietaría como una herramienta nutricional capaz de normalizar la presión arterial, la fosforilación y la vía no oxidativa de la glucosa en el músculo cardíaco en este modelo experimental.The present study analyzes the effect of dietary isolated soy protein on hypertension and impaired glucose metabolism present in the heart muscle of dyslipemic insulin– resistant rats fed a sucrose–rich diet (SRD). Male Wistar rats received a SRD for 4 months. At this time half of the animals continue with the same diet for up to 8 months, the other half was fed an SRD in which isolated soy protein replaced casein as protein source (DRS+PS) for 4 additional months. The control group (CD) consumed control diet throughout the experimental diet. The results obtained show that this dietary manipulation was able to reverse the hypertension normalizing the altered glucose phosphorylation -estimated by hexokinase activity- and glucose 6-phosphate and glycogen content in the heart muscle of SRD fed rats. The replacement of soy protein by casein as protein source normalized plasma levels of triglycerides, NEFA and the moderate hyperglycemia without change of insulinemia. Although the whole body peripheral insulin sensitivity improved significantly values were still higher than those of CD group. The results showed that the dietary soy protein could be a nutritional tool capable to normalized blood pressure, and heart muscle glucose phosphorylation as well as the nonoxidative pathway of glucose in this experimental animal model.Fil: Oliva, Maria Eugenia. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas. Cátedra de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Chicco, Adriana Graciela. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas. Cátedra de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Lombardo, Y. B.. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas. Cátedra de Química Biológica; Argentin

Islet neogenesis: An apparent key component of long-term pancreas adaptation to increased insulin demand

This study aimed to determine the relative importance of different functional and morphological pancreatic changes induced by the chronic administration of a sucrose-rich diet (SRD) to maintain normal glucose homeostasis. Male Wistar rats were fed either sucrose (SRD) or starch (CD) for 6 and 12 months. At both periods, serum glucose and triacylglycerol levels were significantly higher (P<0.05; paired and unpaired Student's t-test) in SRD rats. Serum insulin levels were significantly lower in SRD only at 12 months. At 6 months, the insulin secretion dose-response curve in SRD rats showed a shift to the left that was no longer observed at 12 months, when SRD islets decreased their response to 16 mM glucose. At 6 months, SRD rats showed a significant increase in β-cell volume density (Vvi) and islet cell replication rate, together with a decrease in β-cell apoptotic rate. Changes were not detected in the percentage of PDX-1- and islet neogenesis associated protein (INGAP)-positive cells. Conversely, at 12 months, there was a significant decrease in β-cell Vvi and in the percentage of PDX-1-positive cells; the islet cell replication rate was not modified, and the number of apoptotic β-cells increased significantly. No signs of increased neogenesis or INGAP-positive cells were recorded at any period in SRD rats. Our results show that SRD rats are unable to develop functional and morphological pancreatic reactive changes sufficient to maintain normal glucose and triacylglycerol levels for a long period. Such failure could be ascribed to their inability to increase the rate of neogenesis and of INGAP production.Centro de Endocrinología Experimental y Aplicad

Islet neogenesis: An apparent key component of long-term pancreas adaptation to increased insulin demand

This study aimed to determine the relative importance of different functional and morphological pancreatic changes induced by the chronic administration of a sucrose-rich diet (SRD) to maintain normal glucose homeostasis. Male Wistar rats were fed either sucrose (SRD) or starch (CD) for 6 and 12 months. At both periods, serum glucose and triacylglycerol levels were significantly higher (P<0.05; paired and unpaired Student's t-test) in SRD rats. Serum insulin levels were significantly lower in SRD only at 12 months. At 6 months, the insulin secretion dose-response curve in SRD rats showed a shift to the left that was no longer observed at 12 months, when SRD islets decreased their response to 16 mM glucose. At 6 months, SRD rats showed a significant increase in β-cell volume density (Vvi) and islet cell replication rate, together with a decrease in β-cell apoptotic rate. Changes were not detected in the percentage of PDX-1- and islet neogenesis associated protein (INGAP)-positive cells. Conversely, at 12 months, there was a significant decrease in β-cell Vvi and in the percentage of PDX-1-positive cells; the islet cell replication rate was not modified, and the number of apoptotic β-cells increased significantly. No signs of increased neogenesis or INGAP-positive cells were recorded at any period in SRD rats. Our results show that SRD rats are unable to develop functional and morphological pancreatic reactive changes sufficient to maintain normal glucose and triacylglycerol levels for a long period. Such failure could be ascribed to their inability to increase the rate of neogenesis and of INGAP production.Centro de Endocrinología Experimental y Aplicad

Islet neogenesis: An apparent key component of long-term pancreas adaptation to increased insulin demand

This study aimed to determine the relative importance of different functional and morphological pancreatic changes induced by the chronic administration of a sucrose-rich diet (SRD) to maintain normal glucose homeostasis. Male Wistar rats were fed either sucrose (SRD) or starch (CD) for 6 and 12 months. At both periods, serum glucose and triacylglycerol levels were significantly higher (P<0.05; paired and unpaired Student's t-test) in SRD rats. Serum insulin levels were significantly lower in SRD only at 12 months. At 6 months, the insulin secretion dose-response curve in SRD rats showed a shift to the left that was no longer observed at 12 months, when SRD islets decreased their response to 16 mM glucose. At 6 months, SRD rats showed a significant increase in β-cell volume density (Vvi) and islet cell replication rate, together with a decrease in β-cell apoptotic rate. Changes were not detected in the percentage of PDX-1- and islet neogenesis associated protein (INGAP)-positive cells. Conversely, at 12 months, there was a significant decrease in β-cell Vvi and in the percentage of PDX-1-positive cells; the islet cell replication rate was not modified, and the number of apoptotic β-cells increased significantly. No signs of increased neogenesis or INGAP-positive cells were recorded at any period in SRD rats. Our results show that SRD rats are unable to develop functional and morphological pancreatic reactive changes sufficient to maintain normal glucose and triacylglycerol levels for a long period. Such failure could be ascribed to their inability to increase the rate of neogenesis and of INGAP production.Centro de Endocrinología Experimental y Aplicad