Insulin Binding to Liver Plasma Membranes from Growing Ruminating Sheep. Maintained on Different Diets

Abstract

The purpose of this work was to investigate insulin receptors in growing ruminant sheep given a control diet or undergoing nitrogen restriction. Live weights ranged within 30-36 kg in both groups. Before the animals were fed (i.e. at 8 a.m.) blood insulin was not significantly different in the two groups (0.39 vs 0.53 nM in experimentals and controls, respectively). The 125I-monoiodoinsulin binding to purified liver plasma membranes was studied. Membrane recovery and purity were similar in both groups. Results showed that specific 125I-iodoinsulin binding increased with time and reached a maximum value within 60-120 min. Increasing the nonlabelled insulin level inhibited 125I-iodoinsulin binding at steadystate. Among the animals from both groups, specific insulin binding decreased significantly with increased live weight. In addition, specific insulin binding lowered with increasing blood insulin. The latter relationship partly reflected the insulin binding-live weight-blood insulin relationships. The insulin binding was similar in both groups. Furthermore Scatchard analysis indicated no significant differences between apparent affinity constants and apparent binding capacities in the two groups.

Insulin responsiveness, action and sensitivity in growing lambs and mature rams

“…Therefore, it is possible that insulin action to peripheral tissues increases with developing growth stage under the normal plasma insulin concentrations. By contrast, Grizard et al (1987) (Bergman et al 1989;Metcalf and Weekes 1990;Sano et al 1992Petterson et al 1993. In the present experiment, insulin sensitivity tended to be more sensitive for 5-mo-old lambs than for 9-mo-old lambs and mature rams as suggested by the lower EDro for S-mo-old lambs.…”

“…In the present experiment, insulin sensitivity tended to be more sensitive for 5-mo-old lambs than for 9-mo-old lambs and mature rams as suggested by the lower EDro for S-mo-old lambs. Grizard and Szczygiel (1983) v9-mo-old lambs > 5-mo-old lambs > mature rams (P < 0.05). x9-mo-old lambs and mature rams > 5-mo-old lambs (P < 0.05)' w9-mo-old lambs > 5-mo-old lambs (P < 0.05).…”

“…The present experiment was designed to compare insulin trations changes with growth stage (Bassett tqi+; coooe" i::l-:l'iutnt"' action and sensitivity among ruminanting andweekes l98l; Grizard et al 1987). rh.…”

Orientations et coordination hormonale du métabolisme protéique chez les ruminants

“…L'apparition des récep-teurs hépatiques d'hormone de croissance semblerait coïncider chez les ovins avec une stimulation de l'action de l'IGF, (traduite par l'augmentation de la teneur plasmatique en IGF I ) et l'apparition de protéines de transport de l'IGF, ayant un poids moléculaire élevé (Butler et Gluckman, 1986 Grizard, Patureau-Mirand et Pion, 1976 ;Papet et al, 1987). Pendant la période de croissance au stade ruminant, il y a le plus souvent une augmentation de l'insulinémie moyenne au cours de la journée (Johns et Bergen, 1976 ;Trenkle et Topel, 1978 ;Grizard et Szczygiel, 1983a ;Johnson et al, 1985 ;Heins, Vernaillen et Paquay, 1986 ;revue de Weekes, 1986 (Kappy et al, 1981 ;Sinha, Ganguli et Sperling, 1981 ;Grizard et Szczygiel, 1983b). Il y a sans doute une diminution de la réponse du tissu à l'insuline au cours du développement puisque la baisse des acides aminés libres du sang, provoquée par une injection de l'hormone, est moindre chez l'adulte que pendant la période de croissance (Prior et Christenson, 1978 ;Grizard et al, 1987b1.…”

Contrôle hormonal du métabolisme hépatique chez les ruminants

“…Inversement la réduction du taux de clairance de l'hormone chez les ovins soumis à une réduction des apports énergétiques et azotés de la ration pourrait être due à une baisse de l'élimination hépatique (Grizard et Szczygiel, 1983).…”