Insulin and the glucose-glucagon feedback mechanism in the duck

Laurent, F; Mialhe, P

doi:10.1007/bf01221961

Cited by 23 publications

(30 citation statements)

References 23 publications

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“…At the concentrations used beef and duck insulin crossreact with our antibody [15] and the results are expressed as pg beef IRI equivalents/ml plasma. The sensitivity of the assay was 50 pg/ml and the coefficient of variation between assays at levels between 200 and 300 pg/ml was 19%.…”

Section: Plasma Determinationsmentioning

confidence: 99%

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Somatostatin stimulates glucagon secretion in ducks

et al. 1980

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Summary.In normal fasting ducks, a somatostatin infusion (800ng/kg/min for 30min) elicited a prompt inhibition of insulin secretion, plasma levels falling from 140 _+ 20 to 20 + 6 pg Eq/ml as observed in mammals. -However plasma glucagon-likeimmunoreactivity shown to be decreased in mammals by somatostatin was sharply increased from a mean basal level of 1.46 + 0.13 ng Eq/ml to 6.61 + 0.77 ng Eq/ml. This effect was not mediated via inhibition of growth hormone secretion since it was also observed in hypophysectomised ducks. Despite the fall in plasma insulin and rise in GLI observed with somatostatin infusion in intact birds, plasma glucose concentrations were lower than with control saline infusion. [5,14,22] and it has been shown that somatostatin simultaneously inhibits insulin and glucagon secretion; moreover somatostatin appears to be one of the most effective A cell suppressants known [22]. Key words:In birds, it has been shown that the somatostatin producing D cells are particularly numerous in the islets of the pigeon pancreas [20] and very high somatostatin concentrations have been measured in the chicken pancreas [25]. As the duck appears to be an interesting species for studies on pancreatic hormone regulation [17,18] the present study was undertaken to explore the response of pancreatic hormones to somatostatin infusion in ducks. Materials and Methods AnimalsExperiments were performed on male Peking ducks 3 to 6 months old (2 to 2.5 kg), maintained on a normal diet with fowl pellets and tap water ad libitum. HypophysectomyRemoval of the pituitary was performed under local anaesthesia (1% xylocaine, Bellon) according to Benoit's technique [1]. These animals were used for experiments 4 to 10 days after operation. Completeness of hypophysectomy was checked by plasma growth hormone determination. InfusionsAfter an overnight fast the conscious ducks, normal or hypophysectomised, were tied to a board.Somatostatin was dissolved in 0.154 mol/l saline and administered intravenously as a bolus of 800 ng/kg immediately followed by a sustained infusion of 800 ng/kg/min for 30 minutes through a cathether inserted into a leg vein. As controls, normal or hypophysectomised ducks received 0.154 mol/1 saline infusions. Blood SamplingBlood samples were collected from a catheter inserted into a wing vein immediately before infusion (zero time) and at selected intervals thereafter.Blood samples kept on ice were centrifuged at 4 ~ and plasma stored at -20 ~ until the time of assay. Plasma DeterminationsPlasma glucose concentration was measured with a Technicon autoanalyser using a ferricyanide reagent [11] after dialysis of plasma.

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Section: Plasma Determinationsmentioning

confidence: 99%

“…In pancreatectomised ducks 7/69 GLI is still detectable but not 30K GLI. Therefore it is assumed that variations in 30K GLI represent modifications of GLI of pancreatic origin [15,23].…”

Section: Plasma Determinationsmentioning

confidence: 99%

Somatostatin stimulates glucagon secretion in ducks

et al. 1980

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“…In this assay duck insulin cross-reacts with a bovine insulin antiserum to give standard curves parallel with those of the bovine insulin standard over the range of con¬ centrations found (Laurent & Mialhe, 1976). The results are expressed as mu.…”

Section: Plasma Determinationsmentioning

confidence: 99%

Control of plasma levels of growth hormone, glucagon and insulin in ducklings: roles of free fatty acids and somatostatin

Foltzer¹,

Strosser²,

Harvey³

et al. 1985

Journal of Endocrinology

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The effects of plasma free fatty acids (FFA) and somatostatin-14 (S-14) on concentrations of plasma GH, glucagon and insulin were investigated in juvenile ducks. Oleic acid, S-14 or both were infused into 4- to 7-week-old birds and plasma GH, glucagon-like immunoreactivity (GLI), immunoreactive insulin (IRI) and FFA were measured. An increase in plasma GH and a decrease in GLI but no change in IRI was observed after infusion of 9 mg oleic acid/kg per min. A decrease in plasma GH, FFA and IRI and an increase in plasma GLI was seen after infusion of 800 ng S-14/kg per min. These effects of S-14 on IRI and GLI were abolished when S-14 was infused simultaneously with oleic acid. It is concluded that FFA have a direct stimulatory effect on GH secretion and an inhibitory effect on glucagon secretion. Somatostatin-14 directly inhibits the secretion of GH and its stimulatory effect on the secretion of glucagon is mediated by a depression in concentrations of plasma FFA. Finally, S-14 has no effect on plasma insulin when basal levels of plasma FFA are maintained.

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“…Concen¬ trations of pancreatic GLI were also estimated by a radioimmunoassay (Leclercq-Meyer, Mialhe & Malaisse, 1970) which used porcine glucagon (Novo, Copenhagen, Denmark) as the standard, since the duck pancreas synthesizes a molecular species of glucagon with the same molecular weight as porcine glucagon (V. Leclercq-Meyer & P. Mialhe, unpub¬ lished results). Pancreatic IRI was determined by another heterologous radioimmunoassay (Foltzer & Mialhe, 1976), in which duck insulin gives standard curves parallel to those of the bovine insulin standard used (Laurent & Mialhe, 1976). Statistical differences in the results were determined by Student's r-test.…”

Section: Gel Chromatographymentioning

confidence: 99%

Pancreatic somatostatin, glucagon and insulin during post-hatch growth in the duck (Anas platyrhynchos)

Foltzer¹,

Harvey²,

Mialhe³

1987

Journal of Endocrinology

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Pancreatic somatostatin-like immunoreactivity (SLI), immunoreactive insulin (IRI) and glucagon-like immunoreactivity (GLI) were measured during growth in ducks. The content of each hormone increased progressively but at different rates in the dorsal, ventral and splenic lobes of the pancreas. In the almost fully grown duck, the splenic lobe contained 80 and 63% of the total content of GLI and SLI respectively but low levels of IRI (23%), which were highest in the dorsal lobe (53%). In contrast to the hormonal content, only total GLI concentrations increased during development, the SLI concentrations remaining stable and IRI concentrations declining during growth. Gel filtration of pancreatic extracts indicated that most of the SLI in the pancreas of young and adult birds was somatostatin-14, although somatostatin-28 was present in the ventral lobe of young birds and larger molecular forms were present in the ventral and dorsal lobes. These changes in pancreatic hormonal content and concentration are dissimilar to age-related changes in SLI, GLI and IRI previously observed in the plasma of ducks. Plasma levels of pancreatic hormones may thus be controlled by hormonal and/or neutral factors during post-hatch growth.

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Insulin and the glucose-glucagon feedback mechanism in the duck

Cited by 23 publications

References 23 publications

Somatostatin stimulates glucagon secretion in ducks

Somatostatin stimulates glucagon secretion in ducks

Control of plasma levels of growth hormone, glucagon and insulin in ducklings: roles of free fatty acids and somatostatin

Pancreatic somatostatin, glucagon and insulin during post-hatch growth in the duck (Anas platyrhynchos)

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