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  • 1
    ISSN: 1432-0428
    Keywords: Growth hormone ; somatotrophic diabetes ; metasomatotrophic diabetes ; hyperinsulinaemia ; hypoinsulinaemia ; insulin content of pancreas ; insulin responses to glucose ; glucagon ; arginine ; meals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Growth hormone treatment produced somatotrophic diabetes, with hyperglycaemia, polyuria, glycosuria and elevation in serum non-esterified fatty acids (NEFA) in dogs. Early in this diabetes, fasting serum immunoreactive insulin (IRI) rose 20-fold, the insulin/glucose (I/G) ratio rose 10-fold and in response to glucose infusion, the rise in IRI was twice the normal. In the latter half of the continued growth hormone treatment, the intensity of the diabetes increased, serum IRI declined to the normal level and the I/G ratio became subnormal. Late in the treatment, following glucose infusion, there was no change in serum IRI, no fall in NEFA and further depression of glucose tolerance. In metasomatotrophic diabetes, in which hyperglycaemia, glycosuria and high NEFA level persisted, fasting serum IRI was normal during several months, then became subnormal and the I/G ratio was diminished further. Following glucose IV there was no change in serum IRI, no fall in NEFA and low glucose tolerance. The normally-occurring rises in serum IRI following arginine and glucagon IV and after the ingestion of a meal were absent. These permanently diabetic dogs were responsive to insulin IV. The insulin content of the pancreas was reduced to about 1.2% of the normal after 14 months of this diabetes. From the sequence of change it is concluded that growth hormone induced metasomatotrophic diabetes by causing excessive secretion of insulin under basal and stimulative conditions, leading to permanent loss of function of the beta cells of the pancreatic islets, to such an extent that basal insulin secretion was low and the ability to secrete extra insulin in response to stimuli was lost.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Growth hormone effects ; somatotrophic diabetes ; metasomatotrophic diabetes ; hyperinsulinaemia ; hyperproinsulinaemia ; hypoinsulinaemia ; pancreatic insulin and proinsulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In normal fasting dog serum, the insulin: proinsulin molar proportion was 71:29%. In response to glucose infusion, the proinsulin proportion decreased. In the pancreas, the proinsulin proportion was lower than in serum. Growth hormone treatment for one day increased serum insulin sevenfold and proinsulin 18-fold. The proinsulin proportion increased to 49%. The growth hormone injections magnified the response to glucose infusion. The rise in serum insulin was 16 times the normal, proinsulin also rose but its proportion decreased. Growth hormone treatment for 6 days decreased pancreatic insulin to 5% and proinsulin to 46% of normal. In the permanent (metasomatotrophic) diabetes produced by the prolonged administration of growth hormone, serum insulin decreased and the proinsulin proportion increased. No rises in serum insulin nor proinsulin occurred following glucose infusion. In the pancreas, insulin and proinsulin were reduced to 1.6% and 8% of normal. The reduction in the immunoreactive insulin of the pancreas was more pronounced in the tail than in the head and body regions. The results indicate that in the state of augmented insulin secretion and hyperinsulinaemia produced by growth hormone and in the reduced insulin secretion and hypoinsulinaemia of metasomatotrophic diabetes, the proportion of proinsulin in serum is increased due to beta cell secretion containing a higher proportion of proinsulin than normal.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Insulin release ; insulin biosynthesis ; growth hormone ; calmodulin ; cyclic AMP ; islet glucose metabolism ; hypophysectomy ; cultured islets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects on islet function of addition to the culture medium of rat growth hormone was studied in 4-day cultured islets of Langerhans from normal and hypophysectomised rats. In islets from hypophysectomised rats, rates of insulin release were 34% lower than in control rat islets; rates of insulin plus proinsulin and total protein biosynthesis were also lower by 48% and 16% respectively. The rates of glucose oxidation and the islet content of cyclic AMP were unchanged in islets from hypophysectomised rats but the islet content of calmodulin was decreased by 68%. The presence of rat growth hormone during the culture period restored the secretory response of hypophysectomised rat islets to that seen in control islets cultured without growth hormone but had only a marginal effect on the rate of insulin plus proinsulin biosynthesis, and no significant effect on islet calmodulin content. Glucose oxidation was increased by the presence of growth hormone during the culture period in both control (73% increase) and hypophysectomised (38% increase) rat islets. Addition of growth hormone to the culture medium also enhanced rates of insulin release and biosynthesis in control islets by 116% and 20% respectively. It is suggested that these changes arise primarily from modification of the synthesis of specific islet proteins.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 15 (1978), S. 205-212 
    ISSN: 1432-0428
    Keywords: Growth hormone ; somatotrophic diabetes ; diabetes ; glucagon ; arginine ; serum insulin ; immunoreactive insulin ; hyperinsulinaemia ; insulin secretion ; insulin-secretory responses ; augmentation of insulin secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Growth hormone injected daily in 6 dogs for 6 days caused a 20-fold elevation in fasting serum immunoreactive insulin (IRI) without appreciable change in serum glucose in 1 day. In the somatotrophic diabetes that occurred after 2 days, the hyperinsulinaemia was maintained and the serum IRI/glucose (I/G) ratio declined from the early high level but remained elevated. During this treatment, in response to glucose infusion, the rise in serum IRI above the initially high fasting level was 16 times the normal. In response to glucagon, the rise in IRI was twice the normal and the rise in glucose was more prolonged, resulting in a decline in the I/G ratio. In response to arginine infusion, the rise in serum IRI was 8 times the normal and the rise in the I/G ratio was twice normal. Following a meal, the rise in serum IRI was 8 times the normal. Thus, with growth hormone treatment the insulin secretory responses to these stimulating factors were magnified over the already elevated fasting level of secretion. The insulin content of the pancreas was reduced to less than 10% of normal by growth hormone treatment for 6 days, due apparently to elevation of the rate of secretion over the rate of formation of insulin.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: Enkephalin ; insulin secretion ; islets of Langerhans ; naloxone ; islet culture ; DAMME
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rat islets of Langerhans were maintained for 2 days in tissue culture. Following the culture period, the insulin secretory responses of the islets on incubation in bicarbonate medium were measured. The enkephalin analogue D-ala2, MePhe4, Met(0)-ol (DAMME), 8.3×10-8mol/l, augmented insulin release stimulated by glucose (5 or 7 mmol/l) by 76% and 47% respectively; increased insulin release stimulated by α-ketoisocaproate (7.5 mmol/l) by 23%; and enhanced insulin release in the presence of glibenclamide (10 μg/ml) plus glucose (3.3 mmol/l) by 38%. Insulin release in the presence of glucose at 2 or 12 mmol/l was not affected by DAMME (8.3×10-8mol/l). The potentiatory effect of DAMME on insulin release in the presence of glucose (5 mmol/l) was blocked by naloxone (11 μmol/l): naloxone alone did not affect glucose-stimulated insulin release. A high concentration (3.3×10-6mol/l) of DAMME did not modify glucose-stimulated insulin release. Inhibition of glucose-stimulated insulin release by trifluoperazine, an inhibitor of calmodulin, was not overcome by DAMME. Insulin secretory responses were not enhanced by exposure of the islets to DAMME (8.3×10-8mol/l) during the culture period. It is concluded that insulin release from isolated islets is capable of being influenced by an opioid peptide.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 22 (1982), S. 300-300 
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 29 (1986), S. 119-121 
    ISSN: 1432-0428
    Keywords: Insulin release ; insulin biosynthesis ; dexamethasone ; prednisolone ; hydrocortisone ; aldosterone ; cultured islets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of additions to the culture medium of some natural or synthetic corticosteroid hormones was studied in cultured rat islets of Langerhans. The steroids decreased glucose-induced insulin release. The extent of inhibition by dexamethasone was 18–55%, prednisolone 23%, hydrocortisone 21% and aldosterone 18%. None of them affected the basal secretion of insulin or had any effect on diameter or insulin content of the islet. The inhibitory action of dexamethasone on insulin release was observed in the range 63 nmol/l to 6.3 μmol/l. At 6.3 μmol/l during two h, dexamethasone (a) inhibited insulin response to glucose concentrations above 5 mmol/l (b) caused a delay in the first phase and markedly reduced the second phase of insulin release of perifused islets, and (c) decreased the incorporation of [H3]-leucine into total islet proteins without affecting [H3]-leucine-incorporation into insulin plus proinsulin. It is suggested that steroids, by directly acting on the islets of Langerhans, may modulate the insulin-release response to secretagogues.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 19 (1980), S. 391-396 
    ISSN: 1432-0428
    Keywords: Growth hormone ; hypophysectomy ; plasma growth hormone ; plasma insulin, insulin release ; perifusion ; cultured rat islets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Growth hormone injected intravenously in the rat elicited a 6-fold spike change in immunoreactive insulin with little variation in glucose. Subcutaneous administration of growth hormone for 4 days augmented by 56% the insulin-secretory response to glucose of isolated islets from hypophysectomised rats but not the response of control rat islets. When islets were cultured in the presence of growth hormone, the glucose-induced insulin release was increased by 35% in batch incubations of islets from both normal and hypophysectomised rats and by 70–110% in perifused islets. Thus the capacity for stimulated release of insulin is limited by hypophysectomy, and growth hormone is capable of directly influencing the secretory function of the β- cell.
    Type of Medium: Electronic Resource
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