Changes in red cell insulin receptors during recovery from severe malnutrition

Red cell insulin binding was studied in 13 Jamaican children (age range 4-24 months), while malnourished (MAL), during early recovery (GI), late recovery (GII), and after anthropometric recovery (REC). The rate of weight gain (RW), the energy intake (EN), and the protein intake (PR) were monitored at each phase of the study. Four-hour fasting blood samples were used, and the insulin binding characteristics were investigated in the physiological range of insulin concentrations (16.7-1670 pM). Analyses of variance were used to examine differences in the variables measured at the four phases. Red cell-specific insulin binding (SB) was lower in MAL than in GI (P less than 0.001) and in (GII) (P = 0.026). SB in REC and MAL were not significantly different. Insulin receptor affinity (K) was also lower in MAL than in GI (P less than 0.001). GII (P = 0.001), and REC (P = 0.012). The insulin receptor number (S) appeared to be high in malnutrition and to decrease as recovery progressed; however the decrease was not significant. Children with fever demonstrated high insulin binding. Plasma insulin (IN) rose during recovery, and was significantly higher in GII than in MAL (P = 0.01). There was no difference in plasma glucose (G) at any phase of the study. The interrelationships among the variables measured were investigated longitudinally using multiple regression analyses, SB was positively associated with S (P = 0.032), EN (P = 0.029), and PR (P = 0.0076). S was negatively associated with K (P less than 0.001). The associations of S and K with PR were positive and approached significance (P = 0.09 and P = 0.07 respectively). RW was positively associated with PR (P less than 0.001), and with EN (P = 0.001). There were no significant relationships between G and any of the other variables longitudinally. However, correlations of the variables within phases demonstrated that in MAL, G was negatively associated with SB (P less than 0.05) and with K (P less than 0.05); but in REC, G was positively associated with SB (P less than 0.05). These results demonstrated that in severe malnutrition, the red cell insulin receptor affinity was low. During catch-up growth when protein and energy intakes were increased, both insulin receptor affinity and specific insulin binding were also increased. The negative relationship between insulin binding and plasma glucose during malnutrition may be related to carbohydrate intolerance.