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Effect of bovine somatotropic hormone on insulin response to glucagon-like peptide 1, in dogs
S160
Poster Session I
present preliminary results of TNF-(Y in relation to measures associated with insulin resistance among 34 overweight and obese men (n=12) and women (n=22). This cohort is part of a larger study, which includes 800 diabetics and 200 controls from two sites in Ghana (Accra and Kumasi) and three sites in Nigeria (Enugu, Ibadan, and Lagos) to identify susceptibility genes for type 2 diabetes. Fasting blood samples were collected to measure TNF-(r, glucose, insulin, and lipids. TNF-ol was measured using high sensitivity ELISA kits. Type 2 diabetes was diagnosed as fasting plasma glucose 126 mg/dl. We used bioelectrical impedance analysis to measure fat mass (FM) and fat-free mass (FFM). The average TNF-(r level for the cohort was 6.65 pg/ml, and was slightly higher among men (7.14 * 4.11) than among women (6.38 f 3.14). Using Pearson correlation coefficients, we found TN&X was significantly correlated with insulin sensitivity (1=0.65, p=O.O3) among men. An inverse correlation with HDL was suggested (I=-0.53, p=O.O9). Among women, TNF-(r was significantly correlated with BMI (1=0.63, p=O.O02) and FM (1=0.70, p=O.O005). These results are similar to those observed in developed countries. TNF-(r will be measured in the entire study population of diabetics and controls (n=l,OOO) to further explore this relationship, and results may be available at the time of presentation of this abstract.
P637 Effect of Bovine Somatotropic Hormone on Insulin Response to Glucagon-Like Peptide 1, in Dogs J. PIERLUISSI, R. de Pierluissi, A. de Martinez, Z. Quero. Diabefology Laboratory, Vargas School of Medicine, Central University of Venezuela The gut incretin factors are amplifiers of the insulin response to glucose derived from carbohydrates, which are usually present in an ordinary mixed meal. We have previously found that treatment with bovine growth hormone (bSTH) caused an exaggerated insulin response to food intake, in dogs. We have also produced evidence indicating that the insulin response to IV infusion of glucose combined with gastric inhibitory polypeptide (GIP) is augmented by bSTH treatment in dogs and also in acromegalic patients. In the present study, we have extended our observations to the effects of bSTH administration in dogs on the insulin response to glucose in the presence and absence of the intestinal glucose-dependent glucagon-like peptide 1,7-36 amide (GLP-1). Nine female, mongrel dogs were studied during the control period and also 24 h after a single subcutaneous dose of bSTH, 0.5 mg/kg of body weight. In both occasions, we investigated the insulin response to IV glucose administration, 0.6 g/kg/h, in the presence or absence of co- infused GLP-1, 1.2 prnol!kg/min. Blood samples were taken every 10 min from -10 min to 90 min, followed by separation of plasma for measurements of immunoreactive insulin @RI) and glucose. The results indicated: a) The bSTH administration did not change basal glycemia (P > 0.050, for all comparisons). In response to IV glucose, there was a significant increase in blood glucose above the control level after bSTH injection (PC 0.050) and the response curve was lowered to normal values when GLP-I was co-infused with glucose. b) In the control period, GLP-1 enhanced the insulin response to glucose and this was magnified (300%. PiO.010, from 40 to 60 min) by pre-treatment with bSTH. c)As a result of the greater insulin secretion with relative normoglycemia, the bSTH administration enhanced significantly the value of plasma IRUglucose ratio which was further increased when GLP- 1 was given along with glucose. These observations allowed us to reach the following conclusions: 1) The use of a single, relatively low bSTH dose induces in the dog a marked basal hyperinsulinemia without concomitant rise in blood glucose. 2) The bSTH-increased insulin response to the co-infusion of glucose and GLP- 1, mimicking food intake, lends support to the implication of GLP-1 as a possible mediator in the enhanced IRI response to food intake observed in the bSTH-treated dog. 3) The exaggerated response to the incretin effect of GLP- 1 may have a bearing in the hyperinsulinemia found in naturally occuring hypersomatotropic states such as in human acromegalics.
P638 Mechanisms of Altered Ca*+ ‘Ibmover in ‘Ijpe 2 Diabetes M. BALASUBRAMANYAM, R.A. Balaji, B. Subashini, V. Mohan. Madras Diabetes Research Founaiztion, Chennai, India; Centerfor Biotechnology, Anna University, Chennai, India Purpose: Because of the spatiotemporal and complex nature of Ca2+ signaling and the multiple action of CaZf m various cellular responses, there is an obvious need to study the mechanisms of altered Ca2+ regulation in diabetes mellitus. Using human lymphocytes as a cellular model, we have studied cytosolic calcium (Cai) and various CaZ+ transport pathways in Type 2 diabetes and control subjects. Methods: Lymphocytes were isolated using lymphoprep and by centrifugation procedure from the whole blood of control subjects and 5pe 2 diabetes patients. Fasting plasma glucose, glycated haemoglobin (HbAlc), and lipids were also measured in both groups. Ca2+ ATPase activity was measured by coupled enzyme assay in the presence and absence of thapsigargin (Tg). Cells were incubated with radioactive 45Ca to determine Ca2+ influx and Na+/Ca2+ exchange. Ca2+-specific fluorescent probes such as Fura- and Fluo-3 were used to monitor the Ca2’ signals on a spectrofluorimeter. Results: Basal Cai levels in lymphocytes from 5pe 2 diabetes were significantly (PiO.05) higher compared to mean values in control subjects. Cai was positively correlated with fasting plasma glucose and glycated haemoglobin (HbAlc). In Type 2 diabetes, there was a significant (PcO.05) reduction in plasma membrane calcium (PMCA) ATPase activity compared to control cell membranes. Cells from Type 2 diabetes exhibited an increased Ca2+ mflux (as measured both by Fluo-3 fluorescence and 45Ca assay) as a consequence of Tg-mediated Ca2+ store depletion. Upon addition of Mn2+ (a surrogate of Ca2+), the fura- fluorescence decayed with an exponential time course and the rate and extent of this decline was steeper and greater in cells from 5pe 2 diabetes patients. There was also significant (PcO.05) difference in the Na+/Ca’+ exchange activity in Type 2 diabetes patients, both under resting conditions and after challenging the cells with thapsigargin, when the internal store Ca2+ sequestration was circumvented. Pharmacological activation of protein kinase C in cells from patients resulted in partial inhibition of CaZ+ entry. Conclusion: Cellular Ca2+ accumulation in cells from 5pe 2 diabetes results from a synergistic phenomena of a) reduced PMCA ATPase activity, 2) altered Na+/Caz’ exchange, 3) increased Ca2+ influx and/or altered intracellular molecules of store-operated Ca2+ entry regulators.
P639
Obesity, Insulin,Leptin Resistance and TNF-a Levels in hGH fiansgenic Rats ANA SAN GABRIEL’, Kunio Torii ‘, Michio Takahashi’. ’ Central Research Laboratories, Ajinomoto Co., Inc., Kawasaki, Kanagawa, Japan: ‘Nutritional Health Sci. Group, Ajinomoto Co., Inc., Kawasaki, Kanagawa, Japan A transgene of human growth hormone (hGH) integrated into rats was highly expressed in the brain due to the promoter of the mouse whey acidic protein (WAP) gene. As a consequence, secretion of endogenous rat GH was almost totally blocked and pulsatile secretory pattern disappeared. Only a tlat and low hGH level was circulating peripherally which, however, maintained normal body growth (nose to tail length). These transgenic (TG) rats expressed phenotypes of insulin and leptin resistances associated with severe obesity.Intermittedexogenous intraperitoneal hGH treatments to TG rats for 1 week ameliorated insulin and leptin resistance syndrome. In this study, peripheral tumor necrosis factor (TNF-(u) levels in TG rats were monitored and correlated with the above phenotypes. The outbreak of the insulin resistant syndrome (elevated insulin, glucose, triglyceride and FFA levels, and lowered OGT) was observed in 1 l- to 17- week old rats, but plasma TNF-a levels were still significantly lower than those in controls. Significant elevation of plasma TNF-(r levels occurred in
Poster Session I
present preliminary results of TNF-(Y in relation to measures associated with insulin resistance among 34 overweight and obese men (n=12) and women (n=22). This cohort is part of a larger study, which includes 800 diabetics and 200 controls from two sites in Ghana (Accra and Kumasi) and three sites in Nigeria (Enugu, Ibadan, and Lagos) to identify susceptibility genes for type 2 diabetes. Fasting blood samples were collected to measure TNF-(r, glucose, insulin, and lipids. TNF-ol was measured using high sensitivity ELISA kits. Type 2 diabetes was diagnosed as fasting plasma glucose 126 mg/dl. We used bioelectrical impedance analysis to measure fat mass (FM) and fat-free mass (FFM). The average TNF-(r level for the cohort was 6.65 pg/ml, and was slightly higher among men (7.14 * 4.11) than among women (6.38 f 3.14). Using Pearson correlation coefficients, we found TN&X was significantly correlated with insulin sensitivity (1=0.65, p=O.O3) among men. An inverse correlation with HDL was suggested (I=-0.53, p=O.O9). Among women, TNF-(r was significantly correlated with BMI (1=0.63, p=O.O02) and FM (1=0.70, p=O.O005). These results are similar to those observed in developed countries. TNF-(r will be measured in the entire study population of diabetics and controls (n=l,OOO) to further explore this relationship, and results may be available at the time of presentation of this abstract.
P637 Effect of Bovine Somatotropic Hormone on Insulin Response to Glucagon-Like Peptide 1, in Dogs J. PIERLUISSI, R. de Pierluissi, A. de Martinez, Z. Quero. Diabefology Laboratory, Vargas School of Medicine, Central University of Venezuela The gut incretin factors are amplifiers of the insulin response to glucose derived from carbohydrates, which are usually present in an ordinary mixed meal. We have previously found that treatment with bovine growth hormone (bSTH) caused an exaggerated insulin response to food intake, in dogs. We have also produced evidence indicating that the insulin response to IV infusion of glucose combined with gastric inhibitory polypeptide (GIP) is augmented by bSTH treatment in dogs and also in acromegalic patients. In the present study, we have extended our observations to the effects of bSTH administration in dogs on the insulin response to glucose in the presence and absence of the intestinal glucose-dependent glucagon-like peptide 1,7-36 amide (GLP-1). Nine female, mongrel dogs were studied during the control period and also 24 h after a single subcutaneous dose of bSTH, 0.5 mg/kg of body weight. In both occasions, we investigated the insulin response to IV glucose administration, 0.6 g/kg/h, in the presence or absence of co- infused GLP-1, 1.2 prnol!kg/min. Blood samples were taken every 10 min from -10 min to 90 min, followed by separation of plasma for measurements of immunoreactive insulin @RI) and glucose. The results indicated: a) The bSTH administration did not change basal glycemia (P > 0.050, for all comparisons). In response to IV glucose, there was a significant increase in blood glucose above the control level after bSTH injection (PC 0.050) and the response curve was lowered to normal values when GLP-I was co-infused with glucose. b) In the control period, GLP-1 enhanced the insulin response to glucose and this was magnified (300%. PiO.010, from 40 to 60 min) by pre-treatment with bSTH. c)As a result of the greater insulin secretion with relative normoglycemia, the bSTH administration enhanced significantly the value of plasma IRUglucose ratio which was further increased when GLP- 1 was given along with glucose. These observations allowed us to reach the following conclusions: 1) The use of a single, relatively low bSTH dose induces in the dog a marked basal hyperinsulinemia without concomitant rise in blood glucose. 2) The bSTH-increased insulin response to the co-infusion of glucose and GLP- 1, mimicking food intake, lends support to the implication of GLP-1 as a possible mediator in the enhanced IRI response to food intake observed in the bSTH-treated dog. 3) The exaggerated response to the incretin effect of GLP- 1 may have a bearing in the hyperinsulinemia found in naturally occuring hypersomatotropic states such as in human acromegalics.
P638 Mechanisms of Altered Ca*+ ‘Ibmover in ‘Ijpe 2 Diabetes M. BALASUBRAMANYAM, R.A. Balaji, B. Subashini, V. Mohan. Madras Diabetes Research Founaiztion, Chennai, India; Centerfor Biotechnology, Anna University, Chennai, India Purpose: Because of the spatiotemporal and complex nature of Ca2+ signaling and the multiple action of CaZf m various cellular responses, there is an obvious need to study the mechanisms of altered Ca2+ regulation in diabetes mellitus. Using human lymphocytes as a cellular model, we have studied cytosolic calcium (Cai) and various CaZ+ transport pathways in Type 2 diabetes and control subjects. Methods: Lymphocytes were isolated using lymphoprep and by centrifugation procedure from the whole blood of control subjects and 5pe 2 diabetes patients. Fasting plasma glucose, glycated haemoglobin (HbAlc), and lipids were also measured in both groups. Ca2+ ATPase activity was measured by coupled enzyme assay in the presence and absence of thapsigargin (Tg). Cells were incubated with radioactive 45Ca to determine Ca2+ influx and Na+/Ca2+ exchange. Ca2+-specific fluorescent probes such as Fura- and Fluo-3 were used to monitor the Ca2’ signals on a spectrofluorimeter. Results: Basal Cai levels in lymphocytes from 5pe 2 diabetes were significantly (PiO.05) higher compared to mean values in control subjects. Cai was positively correlated with fasting plasma glucose and glycated haemoglobin (HbAlc). In Type 2 diabetes, there was a significant (PcO.05) reduction in plasma membrane calcium (PMCA) ATPase activity compared to control cell membranes. Cells from Type 2 diabetes exhibited an increased Ca2+ mflux (as measured both by Fluo-3 fluorescence and 45Ca assay) as a consequence of Tg-mediated Ca2+ store depletion. Upon addition of Mn2+ (a surrogate of Ca2+), the fura- fluorescence decayed with an exponential time course and the rate and extent of this decline was steeper and greater in cells from 5pe 2 diabetes patients. There was also significant (PcO.05) difference in the Na+/Ca’+ exchange activity in Type 2 diabetes patients, both under resting conditions and after challenging the cells with thapsigargin, when the internal store Ca2+ sequestration was circumvented. Pharmacological activation of protein kinase C in cells from patients resulted in partial inhibition of CaZ+ entry. Conclusion: Cellular Ca2+ accumulation in cells from 5pe 2 diabetes results from a synergistic phenomena of a) reduced PMCA ATPase activity, 2) altered Na+/Caz’ exchange, 3) increased Ca2+ influx and/or altered intracellular molecules of store-operated Ca2+ entry regulators.
P639
Obesity, Insulin,Leptin Resistance and TNF-a Levels in hGH fiansgenic Rats ANA SAN GABRIEL’, Kunio Torii ‘, Michio Takahashi’. ’ Central Research Laboratories, Ajinomoto Co., Inc., Kawasaki, Kanagawa, Japan: ‘Nutritional Health Sci. Group, Ajinomoto Co., Inc., Kawasaki, Kanagawa, Japan A transgene of human growth hormone (hGH) integrated into rats was highly expressed in the brain due to the promoter of the mouse whey acidic protein (WAP) gene. As a consequence, secretion of endogenous rat GH was almost totally blocked and pulsatile secretory pattern disappeared. Only a tlat and low hGH level was circulating peripherally which, however, maintained normal body growth (nose to tail length). These transgenic (TG) rats expressed phenotypes of insulin and leptin resistances associated with severe obesity.Intermittedexogenous intraperitoneal hGH treatments to TG rats for 1 week ameliorated insulin and leptin resistance syndrome. In this study, peripheral tumor necrosis factor (TNF-(u) levels in TG rats were monitored and correlated with the above phenotypes. The outbreak of the insulin resistant syndrome (elevated insulin, glucose, triglyceride and FFA levels, and lowered OGT) was observed in 1 l- to 17- week old rats, but plasma TNF-a levels were still significantly lower than those in controls. Significant elevation of plasma TNF-(r levels occurred in