Insulin and growth hormone inter-relationships in vitro and in vivo - abstract

ABSTRACT

The effect of growth hormone on insulin release was observed in rabbit pancreas in vitro. Isolated islets and pancreas slices were incubated with varying concentrations of human growth hormone. Insulin released in the medium was measured by double antibody immunoassay. Human growth harmone stimulated insulin release in both pancreas preparations (p=.01). However the response was concentration dependent in that insulin release was inhibited at high concentrations of growth hormone. These observations support the concept that growth hormone plays a physiological role in the control of insulin release. Correlation between insulin and growth hormone levels in vivo was investigated in infants recovering from malnutrition. Plasma immunoreactive insulin was measured by a specially modified assay which descriminated between 0, 3, 6 and 12 uu/ml (P=.01). Growth hormone assay was equally sensitive, detecting 0.16 uu/ml. Fasting hormone levels were observed during acute malnutrition, rapid catch-up growth and recovery. In 19 acutely malnourished children insulin levels were low (2.3ñ0.3 uu/ml) (mean ñ SEM) while growth hormone levels were high (32.5 ñ 7.1). During the phase of rapid growth, insulin levels were significantly increased (4.5 ñ 0.6) (p = 0.025) while growth hormone level was 21.7 ñ 4.1. When growth curves plateaued with recovery, mean insulin level was 2.8 ñ 0.3 while growth hormone was 17.6 ñ 3.4. It is concluded that rapid catch-up after protein-calorie malnutrition is associated with a significant elevation of plasma insulin (AU)