Background/objectives: Subcutaneous adipose tissue grows rapidly during the first months of life. Lipoprotein lipase (LPL) has a quantitatively important function in adipose tissue fat accumulation and insulin-like growth factor-I (IGF-I) is a determinant of neonatal growth. Recent studies showed that LPL mass in non-heparinized serum (LPLm) was an index of LPL-mediated lipolysis of plasma triacylglycerol (TG). The objective was to know the influence of serum LPL and IGF-I on neonatal subcutaneous fat growth, especially on catch-up growth in low birth weight infants.
Subjects/methods: We included 47 healthy neonates (30 males, 17 females), including 7 small for gestational age. We measured serum LPLm and IGF-I concentrations at birth and 1 month, and analyzed those associations with subcutaneous fat accumulation.
Results: Serum LPLm and IGF-I concentrations increased markedly during the first month, and positively correlated with the sum of skinfold thicknesses both at birth (r=0.573, P=0.0001; r=0.457, P=0.0035) and at 1 month (r=0.614, P<0.0001; r=0.787, P<0.0001, respectively). In addition, serum LPLm concentrations correlated inversely to very low-density lipoprotein (VLDL)-TG levels (r=-0.692, P<0.0001 at birth; r=-0.429, P=0.0052 at 1 month). Moreover, the birth weight Z-score had an inverse association with the postnatal changes in individual serum LPLm concentrations (r=-0.639, P<0.0001).
Conclusions: Both serum LPLm and IGF-I concentrations were the determinants of subcutaneous fat accumulation during the fetal and neonatal periods. During this time, LPL-mediated lipolysis of VLDL-TG may be one of the major mechanisms of rapid growth in subcutaneous fat tissue. Moreover, LPL, as well as IGF-I, may contribute to catch-up growth in smaller neonates.