INSULIN SECRETORY RESPONSE OF ISOLATED ISLETS OF LANGERHANS IN PREGNANT RATS: EFFECTS OF DIETARY RESTRICTION

1974 ◽  
Vol 62 (1) ◽  
pp. 137-143 ◽  
Author(s):  
I. C. GREEN ◽  
K. W. TAYLOR
Keyword(s):  
Insulin Secretion ◽  
Food Intake ◽  
Islets Of Langerhans ◽  
Secretory Response ◽  
Pregnant Rats ◽  
Additional Food ◽  
Daily Food ◽  
Isolated Islets Of Langerhans ◽  
Low Glucose ◽  
In Pregnancy

SUMMARY The effects of diet on the altered insulin secretory responses of islets of Langerhans of pregnant rats have been investigated. The daily food intake of pregnant rats was found to exceed that of control non-pregnant rats by 20% on average. Depriving pregnant rats of this additional food resulted in an alteration in the pattern of insulin secretion seen in pregnancy, such that the sensitivity to stimulation by low glucose concentrations was abolished. The contribution made by different components of the diet to the secretory response in pregnancy was investigated. When additional carbohydrate, though not protein, was fed to pregnant rats on a restricted food intake, the sensitivity of the islets to glucose stimulation was restored. It was concluded that the quantity and in particular the carbohydrate content of food eaten by pregnant rats exerts an important influence on the changes in insulin secretion in pregnancy.

scholarly journals Regulation of insulin release from isolated islets of Langerhans of the rat in pregnancy. The role of adenosine 3′:5′-cyclic monophosphate

1973 ◽  
Vol 134 (2) ◽  
pp. 481-487 ◽  
Author(s):  
I. C. Green ◽  
S. L. Howell ◽  
W. Montague ◽  
K. W. Taylor
Keyword(s):  
Insulin Secretion ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Islets Of Langerhans ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Normal Female ◽  
Pregnant Rats ◽  
Isolated Islets Of Langerhans ◽  
In Pregnancy

1. The concentrations of cyclic AMP were compared in islets of Langerhans isolated from the pancreases of normal female and pregnant rats and were higher in islets in pregnancy. 2. There was also a significant increase in adenylate cyclase activity in homogenates of islets from pregnant rats compared with those from normal rats. 3. Increased cyclic AMP concentration in islets from pregnant rats was reflected in increased protein kinase activity. When the cyclic AMP-dependent protein kinase activity was increased by 3-isobutyl-1-methylxanthine this stimulated activity was significantly greater in pregnancy. 4. Insulin-secretion studies with islets from normal and pregnant rats showed that theophylline or 3-isobutyl-1-methylxanthine, which raise intracellular cyclic AMP concentrations, caused a significantly greater insulin secretion in pregnancy. 5. It was also found that in the presence of a glucose concentration too low to stimulate insulin secretion, the latter could be induced if the cyclic AMP concentrations were raised sufficiently with 3-isobutyl-1-methylxanthine. 6. It is suggested that the higher cyclic AMP concentrations observed in islets in pregnancy mediate the greater insulin-secretory capacity, as well as the greater sensitivity of these islets to low glucose concentrations.

EFFECTS OF PREGNANCY IN THE RAT ON THE SIZE AND INSULIN SECRETORY RESPONSE OF THE ISLETS OF LANGERHANS

1972 ◽  
Vol 54 (2) ◽  
pp. 317-325 ◽  
Author(s):  
I. C. GREEN ◽  
K. W. TAYLOR
Keyword(s):  
Islets Of Langerhans ◽  
Fasting Blood Glucose ◽  
Insulin Response ◽  
Secretory Response ◽  
Pregnant Rats ◽  
Adenyl Cyclase Activity ◽  
Pregnant Rat ◽  
Rat Islets ◽  
Increased Sensitivity ◽  
In Pregnancy

SUMMARY The secretory response of rat islets of Langerhans was examined during pregnancy and compared with insulin release in normal rat islets. The threshold for a secretory response to glucose was lowered for islets from pregnant rats by comparison with non-pregnant controls. In addition, such islets showed a greatly increased sensitivity to glucose concentrations over the range 3·5–20 mmol/1. Significantly lower fasting blood glucose levels were found in pregnant rats in vivo, compared with controls. Insulin secretagogues other than glucose were tested for their effects on islets during pregnancy. Despite the high baseline of insulin secretion in response to glucose in pregnancy, there was an additional increased secretory response to arginine and theophylline. In contrast to their response to glucose, pregnant rat islets did not display an increased sensitivity to leucine. Glucagon, while it increased the insulin response of normal islets, had no significant effect on increasing the insulin response from pregnant rat islets suggesting that adenyl cyclase activity is already highly stimulated in pregnancy. In addition, the insulin, DNA and protein content of islets during pregnancy were increased significantly above normal values. The results suggested that rat islets are not only larger in pregnancy, but that they possess a more sensitive mechanism for detecting and responding to glucose and other secretagogues.

THE EFFECT OF EPINEPHRINE AND ISOPROTERENOL ON INSULIN SECRETION AND GLUCOSE UTILIZATION IN ISOLATED ISLETS OF LANGERHANS FROM MICE

1977 ◽  
Vol 84 (1) ◽  
pp. 105-114 ◽  
Author(s):  
Leif Sparre Hermann ◽  
Torsten Deckert
Keyword(s):  
Insulin Secretion ◽  
Islets Of Langerhans ◽  
Glucose Concentration ◽  
Glucose Utilization ◽  
Isolated Islets ◽  
Adrenergic Stimulation ◽  
Blocking Agents ◽  
Isolated Islets Of Langerhans ◽  
Low Glucose ◽  
Adrenergic Blocking

ABSTRACT The effect of epinephrine and isoproterenol in different concentrations and adrenergic blocking agents on glucose induced insulin secretion and glucose utilization was studied in isolated islets of Langerhans from mice. Epinephrine in physiological concentrations significantly inhibited the glucose induced insulin secretion. This effect was not mediated by a change in glucose utilization but involved α-adrenergic stimulation. Isoproterenol significantly stimulated the glucose induced insulin secretion but had no effect on glucose utilization. β-adrenergic stimulation by isoproterenol at low glucose concentration was not sufficient to stimulate insulin secretion. The results are discussed in relation to current theories on the mechanism of glucose induced insulin secretion.

EFFECT OF PROGESTERONE ON INSULIN SECRETION IN THE RAT

1978 ◽  
Vol 76 (3) ◽  
pp. 479-486 ◽  
Author(s):  
J. P. ASHBY ◽  
D. SHIRLING ◽  
J. D. BAIRD
Keyword(s):  
Insulin Secretion ◽  
Cyclic Amp ◽  
Islets Of Langerhans ◽  
Isolated Islets ◽  
Β Cell ◽  
Insulin In Plasma ◽  
Isolated Islets Of Langerhans ◽  
Low Concentrations ◽  
In Pregnancy

Implants of progesterone resulted in an increased amount of insulin in plasma in response to intravenous administration of glucose in the rat. Isolated islets of Langerhans from progesterone-treated animals showed a greater maximum secretory response to glucose than islets from control animals but their sensitivity to low concentrations of glucose was unchanged. Theophylline increased glucose-induced secretion of insulin to a greater extent in progesterone-treated than in control rats and also produced a greater increase in the concentration of cyclic AMP in isolated islets from hormone-treated animals. These results suggest that the effect of progesterone on insulin secretion may be mediated by a change in cyclic AMP levels in the β cell. The possible role of progesterone in increasing the secretion of insulin in pregnancy is discussed.

Insulin secretion in Walker 256 tumor cachexia

1990 ◽  
Vol 258 (6) ◽  
pp. E1033-E1036 ◽  
Author(s):  
L. C. Fernandes ◽  
U. F. Machado ◽  
C. R. Nogueira ◽  
A. R. Carpinelli ◽  
R. Curi
Keyword(s):  
Insulin Secretion ◽  
Islets Of Langerhans ◽  
Adult Male ◽  
Male Rats ◽  
Control Group ◽  
Tumor Bearing ◽  
Isolated Islets Of Langerhans ◽  
Outflow Rate ◽  
Walker 256 ◽  
Walker 256 Tumor

The effect of cachexia on insulin secretion was examined in adult male rats. Isolated islets of Langerhans from Walker 256 tumor-bearing rats secreted less insulin by glucose stimuli as compared with the control group; this was accompanied by significant change in 45Ca2+ outflow rate. Reduced insulin secretion to glucose stimuli in tumor-bearing rats probably led to low insulinemia (one-third). These findings indicate that reduced insulin secretion is probably an important factor for the development of cachexia in Walker 256 tumor-bearing rats.

Maternal diet and insulin secretion in islets of lactating, nonlactating, and young rats

1990 ◽  
Vol 259 (4) ◽  
pp. E568-E575 ◽  
Author(s):  
C. R. Bliss ◽  
D. E. Wiedenkeller ◽  
G. W. Sharp
Keyword(s):  
Insulin Secretion ◽  
Food Intake ◽  
Pancreatic Islets ◽  
Maternal Diet ◽  
Pregnant Rats ◽  
Young Rats ◽  
Dietary Phosphorus ◽  
Bone Calcium ◽  
Peak Lactation

The effects of dietary phosphorus (P) on insulin secretion by pancreatic islets of rats at peak lactation (14 days after parturition) and by islets of nonlactating previously pregnant rats have been determined. In addition, the effects of changed dietary P in the maternal diet on insulin secretion by islets of the 1- and 14-day-old offspring were studied. Lactating rats had increased food intake relative to nonlactating rats and correspondingly increased P intake on the 0.4 and 0.7% P diets. Serum P levels were elevated in lactating rats consuming the 0.7% P feed relative to those on the 0.4% P feed and also relative to the nonlactating rats on the 0.7% P feed. Lactating rats had decreased bone calcium compared with the nonlactating rats. Islets from lactating rats on the 0.7% P feed secreted more insulin in response to glucose or to 3-isobutyl-1-methylxanthine (IBMX) than lactating rats on the 0.4% P feed. Additionally, lactating rats on the 0.7% P feed secreted more insulin in response to glucose than nonlactating rats on the same 0.7% P feed. The maternal diet had no influence on the endocrine pancreatic responses of the 1- and 14-day-old offspring in response to glucose or IBMX.

scholarly journals Chromium-induced inhibition of insulin secretion from isolated Islets of Langerhans

Diabetologia ◽  
1980 ◽  
Vol 18 (3) ◽  
pp. 229-232 ◽  
Author(s):  
T. Ghafghazi ◽  
M. L. McDaniel ◽  
P. E. Lacy
Keyword(s):  
Insulin Secretion ◽  
Islets Of Langerhans ◽  
Isolated Islets ◽  
Isolated Islets Of Langerhans

scholarly journals Regulation of insulin secretion from islets of Langerhans rendered permeable by electric discharge

1982 ◽  
Vol 206 (1) ◽  
pp. 81-87 ◽  
Author(s):  
M. Adel Yaseen ◽  
Kevin C. Pedley ◽  
Simon L. Howell
Keyword(s):  
Insulin Secretion ◽  
B Cells ◽  
Insulin Release ◽  
Islets Of Langerhans ◽  
Electric Discharge ◽  
Significant Inhibition ◽  
Marker Enzyme ◽  
Ultrastructural Studies ◽  
Isolated Islets Of Langerhans ◽  
Vinblastine Sulphate

1. High-voltage electric discharge has been used to increase the permeability of B-cells of isolated islets of Langerhans to facilitate studies of the effects of normally impermeable substances on insulin secretion. 2. The application of an intense electric field increased the [14C]sucrose space of the islets from 37.8±3.1% to 86.2±5.2% of their total volume as assessed by 3H2O content. The cells remained permeable for at least 40min. 3. Ultrastructural studies showed no deleterious changes in the structure of the B-cells after discharge. 4. Insulin secretion from normal islets was unaffected by increasing the medium [Ca2+] from 10nm to 10μm. In the islets that had been rendered permeable by discharge, insulin secretion was significantly increased under these conditions, without any alteration in the release of lactate dehydrogenase, a cytoplasmic marker enzyme. 5. Studies of the dynamics of insulin release during perifusion showed that the response to increased (10μm) Ca2+ concentration was rapid and sustained over a period of at least 13min. 6. Secretion responses to Ca2+ in perifusion established that maximum release in permeabilized islets occurs at approx. 1μm-Ca2+ and half-maximum release occurs at approx. 0.6μm-Ca2+. 7. The study of the effect of agents that interfere with the microtubular microfilamentous system in B-cells using a perifusion system revealed that cytochalasin B caused a considerable increase, whereas vinblastine sulphate caused a significant inhibition, in insulin release in response to 1μm-Ca2+. 8. This technique should facilitate the study of the role of normally impermeable ions and metabolic intermediates in the regulation of insulin secretion.

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