Nsila (Nonsuppressible Insulin-Like Activity) - Fetal Growth-Factor

NSILA is a growth hormone dependent serum peptide closely related to the Somatomedins (SM), whose significance as growth hormones has not yet been clarified in vivo. Factors involved in fetal growth are plentiful, recent data suggesting a possible role of SM. Using a sensitive competitive protein binding assay we have determined NSILA in 23 pregnant women and in 28 paired maternal and cord sera. Mean ± S.E.M. levels (μU/ml) during pregnancy (952 ± 56) were not significantly different from those in 8 non-pregnant women (821 ± 25) and did not change much in the course of pregnancy. NSILA in cord serum (597 ± 38) was significantly lower (p < 0.001) than in correspondent maternal serum (1039 ± 63). Preliminary data indicate a reverse behaviour of NSILA carrier protein. The finding of cord NSILA levels within the normal childhood range is compatible with a role in fetal growth. NSILA carrier protein possibly controls the rate of diaplacental transfer and/or the half-life of NSILA in the fetus.