Presence of pancreatic glucagon in the portal plasma of human neonates. Differences in the insulin and glucagon responses to glucose between normal infants and infants from diabetic mothers

Abstract

Summary. Human neonates have been studied during the first hours of life. Blood glucose, portal plasma insulin and glucagon have been determined both at regular intervals up to 24 h after birth and during an intravenous glucose load performed at the 24th h. A material presenting the immunological characteristics of pancreatic glucagon has been found in the portal plasma of both normal infants and infants from diabetic mothers (IDM). The intravenous glucose load did not suppress plasma glucagon in the normal neonates nor in the IDM. Higher portal plasma glucagon values were observed in the late phase of the intravenous glucose load in normal neonates compared to IDM. Portal plasma insulin has been found higher in IDM both at the 24th h of life and during the early phase of the intravenous glucose tolerance test. The hypothesis is put forward that the behaviour difference in glueagon secretion might be a consequence of the relative hyperinsulinism of IDM with insulin facilitating the entry of glucose into the ~ cell thus permitting a more effective glucagon suppression. Prgscnce do glucagon pancrdatique dans le plasma portal do nouveau-ntis. Diffdrences de r~ponses de l'insuline et du g~ucagon au glucose entre los cnfants normaux et los enfants de m~res diabdtiques.Rd~umd. Los auteurs ont 4tudid des nouveau-ntis humains pendant los premi&res heures de la vie. La glye@mie, les taux d'insuline et de gincagon dans le plasma portal ont @t@ dosgs ~ intervalles r@guliers jusqu'~ la 246me heure apr6s la naissance, de mSme qub au cours d'une surcharge glueosde intraveineuse pratiqude ~ la 246me heure. --Un mat@riel prSsentant les caract@ristiques immunologiques du glucagon pancr@atique a @t@ misen @vidence dans le plasma portal des nouveau-ntis normaux et de mTre diab@tique. La surcharge glueosTe intraveineuse ne r@duit pas Ie taux de glucagon plasmatique chez le nouveau-n@ normal ni chez l'enfant de re@re diabdtique. --Dans la phase tardive de la surcharge glucosde intraveineuse, les valeurs de la glucagon@mie portale sent plus @levSes chez l'enfant normal que chez le nouveau-n4 de re@re diabdtique. L'insulin@mie portale est plus @levde chez le nouveau-n4 de mbre diabdtique ~ la 24brae heure de la vie et ~ la phase initiale de la surcharge glucosde. --L'hypothbse est proposde que la diffdrence de comportement du glucagon pourrait rdsulter de l'hyperinsulinisme relatif de l'enfant de mbre diabdtique, l'insuline favorisant la pdndtration de glucose darts la cellule aet permettant, par ee mSeanisme, une suppression plus effieace de la sdcrTtion de glucagon.

Blood Glucose, Serum Insulin and Glucagon Response to Arginine in Premature Infants

“…Edwards et al (4) have reported that during the first 3 days of life the glucagon secretion in the isolated pancreas of the rat is increased by arginine and not inhibited by glucose. This latter finding has been described also in the human newborn by Luyckx et al (10) using the intravenous glucose tolerance test. An increase in insulin and glucagon in the plasma of premature infants has been found after arginine in this research.…”

Insulin and Glucagon during the Perinatal Period: Secretion and Metabolic Effects on the Liver

“…In addition, in species such as sheep and rabbit in which plasma glucose levels do not decrease at birth, an acute increase of plasma glucagon can nevertheless be observed [40,42]. On the other hand, direct evidence of the inability of glucose to reduce glucagon secretion in the newborn has been indicated by in vivo studies in the rat [59] and human [38,60]. The neonatal insensitivity to hyperglycemia has been pro posed to be due in part to low glucoseinduced insulin release of the neonatal pancreas [61].…”

“…Glucagon concentration in the plasma of the fetus at term has been reported to be similar to that of maternal plasma in the rabbit [12], sheep [14,34,35], monkey [26], and human [32,36,37], Increased plasma glucagon concentrations compared to that of the adult have been observed in the rat fetus at term [24,32] and this concentration rises acutely during the early postnatal period in the human [32,38,39], sheep [40] and rat [41] , In these species, glucagon concentra tions values increase about threefold to a peak between 0 and 1-2 h postpartum and persists at values significantly greater than at birth during the perinatal period. In the rab bit, the increase of circulating glucagon which occurs after birth is more progressive [42] , Therefore, in all species studied, the plasma insulin/glucagon molar ratio is very high in the fetus at term, then decreases dra matically immediately after birth and re mains low during the first hours of extrauter ino life.…”

Fuels, Hormones, and Liver Metabolism at Term and during the Early Postnatal Period in the Rat

“…However, both a decrease in glycemia and an increase in IRG have been reported in the human newborn (70,71). The secretory behavior of the human a-cell at birth may thus be relevant to normal extrauterine adaptation, and altered secretion may contribute to abnormal states of glucoregulation demonstrated in the infants of diabetic mothers.…”