Effect of insulin on glucagon secretion mediated via glucose metabolism of pancreatic a cells in ducks

Abstract

A possible action of insulin via glucose metabolism on the pancreatic A cell response to glucose, was studied in ducks. 2-Deoxyglucose, a nonmetabolizable analogue of glucose was used. In normal ducks, the hyperglycaemia induced by 2-deoxyglucose (IV: 0.5 g/kg) resulted in hyperglucagonaemia, while the same degree of hyperglycaemia, induced by glucose infusion (IV injection 25 mg/kg, and infusion 5 mg/kg/min) immediately suppressed glucagon secretion. In diabetic ducks, two days after subtotal pancreatectomy, glucose responsiveness of the A cell was abolished, but could be restored by insulin treatment before (IM 0.2 U/kg insulin + 8 micrograms/kg glucagon every 6 h) and during (IV 3.6 mU/kg + infusion 0.9 mU/kg/min) the glucose test (IV: 0.5 g/kg). The normal response of the A cell to glucose was not observed in diabetic insulin-treated ducks after the administration of 2-deoxyglucose (IV: 0.5 g/kg). These data suggest an inhibitory effect of the metabolism of glucose on the release of glucagon. In addition, the action of insulin on the A cell may be mediated by its effect on glucose metabolism within the A cell.

Effects of Hexoses and Their Derivatives on Glucagon Secretion from Isolated Perfused Rat Pancreas

“…None of the hexoses nor their derivatives were found to stimulate glucagon secretion. While several investigations have reported that 2-DG stimulated glucagon secretion in vivo (Muller, Faloona and linger 1971;Hedo, Villanueva and Marco 1978;Werner, Benson, Brodsky, Hollander, Asplin, Johnson and Palmer 1980;Laurent, Gross, Lakili and Mialhe 1981) or in vitro {Weir, Knowlton and Martin 1974;Hahn and Ziegler 1977;Gerich, Langlois, Noacco, Karam and Forsham 1973), 2-DG inhibited glucagon secretion markedly and significantly in our studies.…”

“…Insulin secretion was not observed during any perfusion except that involving 16.7mM glucose and 20 mM glucosamine. It has been reported that glucagon secretion from A cells is regulated by insulin from B cells (Samols, Tyler and Marks 1972;linger et al 1977;Laurent et al 1981;Filipponi, Gregorio, Cristallini, Ferrandina, Nicoletti and Santeusanio 1986). From the present data, inhibition of IRG secretion might result from a direct action of the hexoses on the A-cells.…”

Concentraciones de glucemia e insulinemia en pollos broilers machos y hembras de cuatro semanas de edad y su relación con el peso

“…En las aves, los islotes se describen de acuerdo con la especie y el sitio lobar; sin embargo, de manera general los islotes están formados por cuatro tipo de células distintas: α, β, δ y F, productoras respectivamente de glucagón, insulina, somatostatina y polipéptido pancreático (2)(3)(4)(5). La insulina es una hormona anabólica que regula el metabolismo de glucosa, lípidos, proteínas y factor de crecimiento (6).…”

“…La liberación de insulina en las aves no se afecta por el ayuno, las hormonas y la estimulación vagal. En sistemas aviar in vitro, la insulina no tiene efectos antilipolíticos y es poco lipogénica; esta es una diferencia en relación con los mamíferos y humanos (4,9). Los receptores β-adrenérgicos en pollos regulan la secreción adrenérgica de insulina (21).…”

Diabetes mellitus concurrent with hepatic haemosiderosis in two macaws (Ara severa, Ara militaris)

“…Most of our knowledge of the avian endocrine pancreas originates from experimental work with domestic granivorous species, chiefly Anseriformes (Laurent et al, 1981;Karmann & Mialhe, 1982). Some studies indicate that these species may differ from mammals in the physiology of blood glucose control.…”