Catecholaminergic responses of neonatal adrenal gland to insulin.

In the present work we study a sequential degree of response to insulin (0.001 IU/g body weight) in neonatal rats, using as parameters the blood glucose and the adrenal catecholamine levels. In 1-day and 90-day-old rats treated by insulin the glycemia showed a more marked fall than the rest of neonates. After insulin administration noradrenaline content did not show differences between control and treated rats. In contrast, adrenaline depletion was significant in adults (62.20%) and in neonates of 7 and 10 days of age (45% and 35.5% respectively). No significant decrease of the amine was observed in the younger rats (1 to 4-days-old). This response to insulin probably depends on the gradual maturation and innervation of the adrenal chromaffin tissue.