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Biomedical subjects

A Sener

Publications and source records attributed to A Sener.

At least 37 records · Page 2Linked to original sources

Assessment by D-[(3)H]mannoheptulose uptake of B-cell density in isolated pancreatic islets from Goto-Kakizaki rats.

The uptake of D-[3H]mannoheptulose by isolated pancreatic islets was recently proposed as a tool to assess the relative contribution of insulin-producing cells to the total mass of the islets. In the present study, the uptake of the tritiated heptose over 60 min incubation at 37 degrees C was about 21% lower in islets from hereditarily diabetic rats (GK rats) than in islets from control animals, this decrease being virtually identical to that documented previously by morphometric analysis of islets from the same type of rats. The intracellular 3HOH space and extracellular [U-14C]sucrose space were not significantly different in control and diabetic rats, at least when the comparison was restricted to animals of the same sex. There was a trend, however, towards a somewhat lower D-[5-3H]-glucose intracellular distribution space in islets from GK rats, as compared to control animals. These findings provide further support to the validity of D-[3H]mannoheptulose uptake as a tool to assess the density of insulin-producing cells in isolated islets.

Animals↗

Enzymic activities in two populations of purified rat islet beta-cells.

In terms of glucose sensing by pancreatic islet beta-cells, emphasis is currently placed on both the role of glucokinase, with negligible activity of low-Km hexokinase(s), and the prevalence of the oxidative over non-oxidative modality of glycolysis, a situation tentatively attributed, in part at least, to a low activity of lactate dehydrogenase. Conflicting information is available, however, on the activity of both low-Km hexokinase(s) and lactate dehydrogenase in purified beta-cell homogenates. This issue was reinvestigated, therefore, in two populations of purified rat islet beta-cells selected on the basis of their low (betaL) or high (betaH) content in reduced pyridine nucleotides. The size and protein content of betaH cells represented about twice that of betaL cells. Such was also the case for low-Km hexokinase(s), lactate dehydrogenase, mitochondrial FAD-linked glycerophosphate dehydrogenase, glutamate dehydrogenase and glutamate-alanine and glutamate-aspartate transaminases. Whether in betaH or betaL cells, the activity of low-Km hexokinase(s) was at least as high as or higher than that of glucokinase. In both betaH and betaL, the activity of lactate dehydrogenase exceeded that required to catalyze the full reduction of glucose-derived pyruvate to L-lactate, as estimated from the rate of D-glucose phosphorylation under physiological conditions. These findings thus argue against a low expression of either low-Km hexokinase(s) or lactate dehydrogenase as major determinants of the glucose-sensing device in beta-cells.

Alanine Transaminase↗

Anomeric specificity of human liver and B-cell glucokinase: modulation by the glucokinase regulatory protein.

The anomeric specificity of the wild-type recombinant forms of human liver and B-cell glucokinase was investigated using radioactive anomers of d-glucose as tracers. With d-glucose at anomeric equilibrium and at 30 degrees C, the maximal velocity, Hill number, and K(s) amounted, respectively, to 16 micromol min(-1) mg(-1), 1.8 and 6.9 mM in the case of liver glucokinase, and 7.3 micromol min(-1) mg(-1), 2.0 and 7.1 mM in the case of B-cell glucokinase. Whether at 20-22 or 30 degrees C, the maximal velocity, Hill number, and K(m) were significantly lower with alpha-d-glucose than with beta-d-glucose in both liver and B-cell glucokinase. As a result of these differences, the reaction velocity was higher with alpha-d-glucose at low hexose concentrations, while the opposite situation prevailed at high hexose concentrations. In the presence of 0.2 mM d-fructose 6-phosphate, the glucokinase regulatory protein caused a concentration-related inhibition of d-glucose phosphorylation, such an effect fading out at high concentrations of either d-glucose or glucokinase relative to that of its regulatory protein. The phosphorylation of alpha-d-glucose by liver glucokinase appeared more resistant than that of beta-d-glucose to the inhibitory action of d-fructose 6-phosphate, as mediated by the glucokinase regulatory protein. Such a phenomenon failed to achieve statistical significance in the case of the B-cell glucokinase. It is proposed that this information, especially the novel findings concerning the anomeric difference in both Hill number and sensitivity to the glucokinase regulatory protein, should be taken into account when considering the respective contributions of alpha- and beta-d-glucose to the overall phosphorylation of equilibrated d-glucose by glucokinase.

Adaptor Proteins, Signal Transducing↗

Chronic furosemide treatment alters renal responses to furosemide in conscious lambs.

Despite the widespread chronic use of furosemide in the clinical management of a variety of fluid and electrolyte disorders in human infants, the physiological responses to furosemide in the newborn after chronic furosemide treatment are not known. The present experiments were conducted to determine the effects of chronic furosemide treatment on renal responses to acute furosemide challenge in conscious, chronically instrumented lambs. Experiments were carried out on day 1 (before chronic treatment) and on day 7 (after chronic treatment) in lambs given intravenous injections of either furosemide (1 mg/kg per 12 h for 5 days, n=9) or vehicle (0 mg/kg per 12 h for 5 days, n=4). Furosemide-treated animals responded to acute furosemide challenge on day 7 with attenuation of natriuresis and diuresis, and augmentation of kaliuresis compared with responses on day 1. Baseline renin production was elevated, although the renin response to furosemide was similar in chronic furosemide-treated and vehicle-treated lambs. Baseline aldosterone levels were not altered by chronic furosemide treatment, but the aldosterone response to acute furosemide injection was decreased after chronic furosemide treatment. Therefore, chronic furosemide treatment alters renal responses to furosemide in conscious lambs, and alters the aldosterone response to acute furosemide challenge.

Aldosterone↗

Dietary effects on insulin and nutrient metabolism in mesenteric lymph node cells, splenocytes, and pancreatic islets of BB rats.

The present studies were performed to determine if a protective diet has different effects on the metabolic activity or function of islet cells, as well as the metabolic activity of mesenteric lymph node (MLN) cells and spleen cells, from BioBreeding (BB) rats. Diabetes-prone BB (BBdp) rats and control non-diabetes-prone BB (BBc) rats were fed for about 20 days either a mainly plant-based diabetogenic diet, NIH-07 (NIH), or a protective semipurified diet with hydrolyzed casein (HC) as the amino acid source. At 6 to 8 weeks of age, BBdp rats had high plasma D-glucose and low insulin concentrations, low insulin content, and low metabolic and secretory responses to D-glucose in isolated pancreatic islets. Islet metabolism, as measured by accumulation of 14C-acidic metabolites, amino acids, and the ratio of D-[U-14C]glucose oxidation and D-[5-3H]glucose utilization was increased in control rats fed HC (P < .05); a similar trend in BBdp rats was not significant. Feeding the HC diet increased islet insulin content (P < .01) by 13% in BBdp and 23% in BBc rats; other metabolic and hormonal variables were unaffected. Compared with BBc rats, BBdp rats displayed higher rates of L-[U-14C]glutamine oxidation, D-[5-3H]glucose utilization, and D-[U-14C]glucose oxidation in MLN cells, but not in splenocytes. There was a dramatic decrease of L-[U-14C]glutamine oxidation in MLN cells from BBc and BBdp rats fed HC. Glycolysis was decreased in control rats. We conclude that the protection afforded by feeding BBdp rats a HC diet is associated with increased insulin in target beta cells and downregulation of metabolic activity in gut-associated MLN cells. Metabolic activity in splenocytes, cells representative of the systemic immune system, was less affected. These data suggest that diet-induced metabolic changes occur in the islets and nearby cells of the gut immune system in the period before classic insulitis. Changes in the islets were smaller in comparison to the dramatic remodeling of nutrient catabolism in MLN cells. MLN downregulation may reflect baseline metabolic activity in the absence of diabetogenic (or other) food antigens and further highlights an important interaction between diabetogenic food antigens and the gut immune tissues.

Amino Acids↗

Lectin affinity chromatography and electrophoretic properties of human platelet gamma-glutamyl transferase.

The sialoglycoprotein, gamma-glutamyl transferase (GGT, gamma-GT, EC 2.3.2.2) is a membrane enzyme found in many cells including platelets and leukocytes. In platelets GGT converts leukotriene C4 (LTC4) to leukotriene D4 (LTD4) and is involved in glutathione metabolism. In this study, human platelet GGT was solubilized with Triton X-100 and purified by lectin affinity chromatography on Con A Sepharose 4B to determine its electrophoretic properties. The specific activity of purified GGT was 236 mU/mg protein; 73.7% of human platelet GGT activity was found bound to Con A and 50% of the bound activity was released with 0.3 mol/l methyl alpha-D-mannopyranoside. We observed that human platelet GGT has only one isoenzyme band showing a carbohydrate stained band near the origin on polyacrylamide gel electrophoresis (PAGE). The electrophoretic mobility of papain-solubilized GGT was higher than that of Triton X-100-solubilized GGT at PAGE. Also GGT activities were determined on neuraminidase, trypsin or n-butanol-DIPE (diisopropyl ether)-treated Triton X-100-solubilized membrane fractions. This characterization may be useful when trying to establish the contribution of platelet GGT to serum GGT activity. This marker may reflect the extent of platelet activation.

Adult↗

Renin and heart rate responses to haemorrhage are age dependent in conscious lambs.

The present experiments were carried out in conscious lambs (1-2 weeks old, n = 9) and older sheep (11-12 weeks old, n = 11) to determine whether the cardiovascular and endocrine responses to 0, 10 and 20 % haemorrhage were developmentally regulated. The major novel finding of our study is that throughout the first 3 months of postnatal life, there is a similar decrease in mean arterial pressure and a similar restoration of pressure to pre-haemorrhage levels, for the same degree of blood loss, yet the mechanisms used to restore pressure appear to be age dependent as follows. In lambs, but not in older sheep, heart rate increased for 1 h after 20% haemorrhage. Activation of the renin-angiotensin system was also greater and more prolonged in lambs than in older sheep following haemorrhage, and occurred at a lesser degree of blood loss. Plasma arginine vasopressin responses to haemorrhage were, however, similar in both age groups. These data provide new information that some of the mechanisms used to restore arterial pressure following blood volume depletion appear to be age dependent.

Aging↗

Feeding a protective hydrolysed casein diet to young diabetic-prone BB rats affects oxidation of L[U-14C]glutamine in islets and Peyer's patches, reduces abnormally high mitotic activity in mesenteric lymph nodes, enhances islet insulin and tends to normalize NO production.

The present studies were undertaken to examine concomitant diet-induced changes in pancreatic islets and cells of the gut immune system of diabetes-prone BB rats in the period before classic insulitis. Diabetes-prone (BBdp) and control nondiabetes prone (BBc) BB rats were fed for approximately 17 days either a mainly plant-based standard laboratory rodent diet associated with high diabetes frequency, NIH-07 (NIH) or a protective semipurified diet with hydrolyzed casein (HC) as the amino acid source. By about 7 weeks of age, NIH-fed BBdp rats had lower plasma insulin and insulin/glucose ratio, lower insulin content of isolated islets, lower basal levels of NO but higher responsiveness of NO production to IL-1beta in cultured islets, and higher Con A response and biosynthetic activities in mesenteric lymphocytes than control rats fed the same diet. In control rats, the HC diet caused only minor changes in most variables, except for a decrease in oxidation of L-[U-14C]glutamine in Peyer's patch (PP) cells and an increase in protein biosynthesis in mesenteric lymphocytes. In BBdp rats, however, the HC diet increased plasma insulin concentration, islet insulin/protein ratio, and tended to normalize the basal and IL-1beta-stimulated NO production by cultured islets. The HC diet decreased oxidation of L[U-14C]glutamine in BBdp pancreatic islets, whereas oxidation of L-[U-14C]glutamine in PP cells was increased, and the basal [Methyl-3H]thymidine incorporation in mesenteric lymphocytes was decreased. These findings are compatible with the view that alteration of nutrient catabolism in islet cells as well as key cells of the gut immune system, particularly changes in mitotic and biosynthetic activities in mesenteric lymphocytes, as well as basal and IL-1beta stimulated NO production, participate in the sequence of events leading to autoimmune diabetes in BB rats. Thus, the protection afforded by feeding a hydrolysed casein-based diet derives from alterations in both the target islet tissue and key cells of the gut immune system in this animal model of type 1 diabetes.

Administration, Oral↗

Pancreatic fate of 6-deoxy-6-[125I]iodo-D-glucose: in vitro experiments.

The apparent distribution space of 6-deoxy-6-[125I]iodo-D-glucose, recently proposed as a tracer of D-glucose transport, was measured in rat isolated islets, acinar tissue, and pieces of pancreas. While such a space reached a steady-state value corresponding to the 3HOH volume in pancreatic islets within 5 min, it slowly increased in pieces of pancreas and, even after 60-min incubation, remained lower than the 3HOH volume. Moreover, the net uptake of 6-deoxy-6-[125I]iodo-D-glucose by pancreatic pieces was inhibited by unlabeled 6-deoxy-6-iodo-D-glucose, D-glucose, and cytochalasin B, while being less or not affected by these agents in isolated islets. A preferential labeling of the endocrine, relative to exocrine, moiety of the pancreas was documented both by comparing, after 2 min incubation, the uptake of 6-deoxy-6-[125I]iodo-D-glucose by pieces of pancreas from normal vs streptozotocin-injected rats and by comparing the radioactive content of pancreatic islets and acinar tissue obtained from normal rats injected intravenously 3 min before sacrifice with 6-deoxy-6-[125I]iodo-D-glucose. It is proposed, therefore, that advantage could conceivably be taken from the vastly different time course for the uptake of selected monosaccharides by pancreatic islets vs acinar cells in the perspective of imaging of the endocrine pancreas by a non invasive method.

Animals↗

Stimulus-secretion coupling of arginine-induced insulin release: comparison between the cationic amino acid and its methyl ester.

The role currently ascribed to the accumulation of L-arginine in the pancreatic islet B-cell as a determinant of its insulinotropic action was reevaluated by comparing the uptake and the metabolic, ionic, electric, and secretory effects of the cationic amino acid with those of its more positively charged methyl ester in rat pancreatic islets. The response to L-arginine methyl ester differed from that evoked by the unesterified amino acid by a lower uptake and oxidation, lack of inhibitory action on D-glucose metabolism, more severe inhibition of the catabolism of endogenous L-glutamine, inhibition of 45Ca net uptake, decrease in both 86Rb outflow from prelabeled islets perifused at normal extracellular Ca2+ concentration and 45Ca efflux from prelabeled islets perifused in the absence of extracellular Ca2+, and delayed and lesser insulinotropic action. These findings reinforce the view that the carrier-mediated entry of L-arginine into the islet B-cells, with resulting depolarization of the plasma membrane, represents the essential mechanism for stimulation of insulin release by this cationic amino acid.

Animals↗

Impairment by cytochalasin B of the inhibitory action of D-mannoheptulose upon D-glucose metabolism in rat pancreatic islets.

D-mannoheptulose was recently found to inhibit D-glucose metabolism in hepatocytes and pancreatic islets, whilst failing to do so in parotid cells, erythrocytes and the exocrine pancreas. In the latter three systems, however, the hexaacetate ester of D-mannoheptulose efficiently inhibits D-glucose metabolism. It was proposed, therefore, that the transport of unesterified D-mannoheptulose into cells may be mediated by GLUT2. Since cytochalasin B is known to inhibit D-glucose transport into pancreatic islet cells, it was now investigated whether the mould metabolite (0.02 mM) also impairs the inhibitory action of D-mannoheptulose (1.0 mM) upon D-glucose metabolism in rat pancreatic islets. The relative extent of D-mannoheptulose inhibitory action on D-[5-3H]glucose utilization and D-[U-14C]glucose conversion to 14CO2, as well as radioactive amino acids and acidic metabolites, was indeed much less marked in the presence of cytochalasin B (13+/-4% inhibition) than in its absence (40+/-3% inhibition). A comparable situation was not observed, however, in the case of glucose-stimulated insulin secretion, cytochalasin B augmenting insulin output to the same relative extent in the absence or presence of D-mannoheptulose. These findings support the view that the entry of D-mannoheptulose into cells may be mediated by a cytochalasin B-sensitive transport system, such as the GLUT2 carrier.

Animals↗

Possible role of diadenosine polyphosphates in glucose-stimulated insulin release: effects of NaF upon metabolic and functional variables in rat isolated islets.

Diadenosine polyphosphates, such as diadenosine triphosphate (A2P3) and diadenosine tetraphosphate (A2P4), were recently proposed to participate in the stimulus-secretion coupling for nutrient-stimulated insulin release. Since NaF, an inhibitor of inorganic pyrophosphatase, was reported to lower A2P3 and A2P4 content in glucose-stimulated pancreatic islets, its effects upon metabolic, cationic, biosynthetic and secretory variables in rat pancreatic islets were investigated in the present study. Up to a concentration close to 0.1 mM, NaF failed to affect most of these variables, except for a decrease in 45Ca net uptake. Much higher concentrations of NaF (e.g. 5.0 mM) were required to cause inhibition of the metabolic, ionic, biosynthetic and secretory responses of the islets to nutrient secretagogues. Yet, even at this high concentration, NaF failed to lower the islet content in tritiated A2P3 and A2P4 in islets prelabelled with [2,8-3H]adenosine and failed to prevent the glucose-induced increase in such a content. It is concluded, therefore, that NaF may not represent a suitable tool to assess the participation of diadenosine polyphosphates in the process of nutrient-induced insulin secretion.

Animals↗

Effects of D-mannoheptose and D-glycero-D-gulo-heptose upon D-glucose metabolism and insulinotropic action in rat pancreatic islets and D-glucose phosphorylation by hexokinase isoenzymes: comparison with D-mannoheptulose.

The possible use of D-mannoheptose or D-glycero-D-gulo-heptose as substitute of D-mannoheptulose for specific inhibition of D-glucose phosphorylation, metabolism and insulinotropic action was investigated in the present study. The two aldoheptoses failed to duplicate the effect of D-mannoheptulose upon the phosphorylation of D-glucose by yeast hexokinase, bovine heart hexokinase or human B-cell glucokinase. They were poorly phosphorylated by the low-Km hexokinase isoenzymes or liver B-cell glucokinase. D-mannoheptose failed to reproduce the inhibitory action of D-mannoheptulose upon D-glucose metabolism by isolated rat pancreatic islets. Whilst D-glycero-D-gulo-heptose failed to affect glucose-induced insulin release, D-mannoheptose slightly enhanced glucose-induced insulin release when tested at low concentrations (0.75-1.5 mM) and progressively decreased insulin output at higher concentration (3. 0-20.0 mM) in islets exposed to a high (16.7 mM), but not physiological (8.3 mM), concentration of D-glucose. D-mannoheptose, however, also caused a modest inhibition of insulin release evoked by 2-ketoisocaproate. It is concluded, therefore, that neither D-mannoheptose nor D-glycero-D-guloheptose can be considered as suitable substitutes of D-mannoheptulose.

Animals↗

D-mannoheptulose uptake and its metabolic and secretory effects in human pancreatic islets.

D-mannoheptulose was recently proposed to be transported into cells at the intervention of GLUT2. Since GLUT1, rather than GLUT2, represents the major carrier system for the transport of monosaccharides across the islet B-cell plasma membrane in human subjects, the uptake of D-mannoheptulose and its metabolic and secretory effects were investigated in human islets. The uptake of D-glucose reached much more rapidly a close-to-equilibrium value in isolated islets than in pieces of pancreas obtained from the same donor. The distribution space of D-[3H]mannoheptulose in the human islets largely exceeded that of [U-14C]sucrose, considered as an extracellular marker, and did not differ significantly from that of 3HOH. In the human islets, the heptose (10.0 mM) inhibited both D-[5-3H]glucose utilization and D-[U-14C] glucose oxidation, and decreased glucose-stimulated insulin release to the same extent as D-mannoheptulose hexaacetate. These findings indicate that a suitable radioactive analog of D-mannoheptulose could be used, in human like in rat islets, for preferential labelling of the endocrine moiety of the pancreatic gland.

Carbon Radioisotopes↗

Pancreatic fate of 6-deoxy-6-[125I]iodo-D-glucose: in vitro experiments.

The apparent distribution space of 6-deoxy-6-[125I]iodo-D-glucose, recently proposed as a tracer of D-glucose transport, was measured in rat isolated islets, acinar tissue, and pieces of pancreas. While such a space reached a steady-state value corresponding to the 3HOH volume in pancreatic islets within 5 min, it slowly increased in pieces of pancreas and, even after 60-min incubation, remained lower than the 3HOH volume. Moreover, the net uptake of 6-deoxy-6-[125I]iodo-D-glucose by pancreatic pieces was inhibited by unlabeled 6-deoxy-6-iodo-D-glucose, D-glucose, and cytochalasin B, while being less or not affected by these agents in isolated islets. A preferential labeling of the endocrine, relative to exocrine, moiety of the pancreas was documented both by comparing, after 2 min incubation, the uptake of 6-deoxy-6-[125I]iodo-D-glucose by pieces of pancreas from normal vs streptozotocin-injected rats and by comparing the radioactive content of pancreatic islets and acinar tissue obtained from normal rats injected intravenously 3 min before sacrifice with 6-deoxy-6-[125I]iodo-D-glucose. It is proposed, therefore, that advantage could conceivably be taken from the vastly different time course for the uptake of selected monosaccharides by pancreatic islets vs acinar cells in the perspective of imaging of the endocrine pancreas by a non invasive method.

3-O-Methylglucose↗

Effects of high extracellular K(+) concentrations, diazoxide and/or Ca(2+) deprivation upon D-glucose metabolism in pancreatic islets.

A rise in D-glucose concentration may augment insulin release independently of changes in K(+) conductance or Ca(2+) influx in pancreatic islet cells, the insulinotropic action of the hexose remaining dependent on an increased generation of high-energy phosphates. In the present study, therefore, it was investigated to which extent the procedures currently used to assess the modalities of the secretory response to D-glucose independent of its effect on ATP-sensitive K(+) channels and Ca(2+) inflow may themselves affect the catabolism of the hexose in isolated rat pancreatic islets. A rise in the extracellular K(+) concentration from 5 to 30 or 60 mM failed to significantly affect the metabolism of D-glucose. At 90 mM K(+), however, the maximal velocity of the glycolytic flux was decreased and the apparent K(m) for D-glucose lowered, without an obvious alteration of the preferential stimulation of oxidative mitochondrial events in response to a rise in D-glucose concentration. Such a preferential stimulation was abolished, however, either by diazoxide at a low, but not high, K(+) concentration or by Ca(2+) deprivation, in the absence or presence of diazoxide, at a high K(+) concentration. It is speculated that these metabolic changes may be attributable, in part at least, to an altered activity of key cytosolic (e.g. pyruvate kinase) and mitochondrial (e.g. FAD-linked glycerophosphate dehydrogenase) enzymes.

Animals↗

Metabolic and secretory response to D-fructose in pancreatic islets from adult rats injected with streptozotocin during the neonatal period.

The metabolic and secretory responses to D-glucose and/or D-fructose were measured in pancreatic islets prepared from either control rats or animals that had been injected with streptozotocin during the neonatal period (STZ rats). The STZ rats displayed higher plasma D-glucose concentrations, but lower plasma insulin concentrations, islet insulin content, as well as basal and nutrient-stimulated insulin release. This coincided with lower rates of D-[U-(14)C]hexose oxidation and D-[5-(3)H]hexose utilization. In both control and STZ rats, D-fructose failed to affect significantly the metabolism of d-glucose, while the aldohexose increased the ratio between D-[U-(14)C]fructose oxidation and D-[5-(3)H]fructose conversion to (3)HOH. Such a ratio was higher than that found with radioactive D-glucose in islets exposed to both hexoses, whether in control or STZ rats, indicating a far-from-negligible contribution of fructokinase to the phosphorylation of D-fructose. Despite these analogies between both the respective fate of D-glucose and D-fructose and the reciprocal metabolic effects of the two hexoses in islets from control and STZ rats, the secretory response to the ketohexose in islets from STZ rats was preferentially suppressed, relative to that evoked by the aldohexose. This gives support to the idea that the insulinotropic action of D-fructose may not be entirely accounted for by its nutritional value in islet cells.

Animals↗

Effects of a protective hydrolyzed casein diet upon the metabolic and secretory responses of pancreatic islets to IL-1beta, cytokine production by mesenteric lymph node cells, mitogenic and biosynthetic activities in Peyer's patch cells, and mitogenic activity in pancreatic lymph node cells from control and diabetes-prone BB rats.

The effects of substituting a plant-based control diabetogenic diet (NIH diet) by a protective hydrolyzed casein diet (HC diet) upon selected metabolic and functional variables were recently investigated in Peyer's patch cells, splenocytes, mesenteric lymph node cells, and pancreatic islets from either control (BBc) or diabetes-prone (BBdp) BB rats. In the present work, the plasma d-glucose and insulin concentrations, the protein and insulin content of pancreatic islets, the metabolism of d-glucose, and its insulinotropic action in islets first cultured for 24 h in the absence or presence of IL-1beta, the production of IFN-gamma and IL-10 by mesenteric lymph node cells cultured for 48 h in the absence or presence of concanavalin A, the mitogenic activity of Peyer's patch cells and pancreatic lymph node cells in the absence or presence of the same lectin, and the biosynthetic activity of Peyer's patch cells were measured in the BBc and BBdp rats fed either the NIH or the HC diet. Two major novel findings emerged from this study. First, in immune cells, diet HC increased to a greater extent the responsiveness to concanavalin A of certain metabolic and functional variables in BBdp rats than in BBc rats. Second, pancreatic islet cells of BBdp rats were less sensitive to IL-1beta than those of BBc rats and this difference was further accentuated when the animals were fed the HC rather than the NIH diet. These findings afford further support to the view that, in BB rats, changes in the biological behavior of Peyer's patch cells, mesenteric and pancreatic lymph node cells, and pancreatic islet cells participate in the pathogenesis of insulin-dependent diabetes mellitus and its prevention by a suitable dietary manipulation.

Animals↗