Adiponectin polymorphisms, cord blood levels of adiponectin, and body composition

Umbilical Cord Blood Adiponectin, Leptin, Insulin, and Ghrelin in Premature Infants and Their Association With Birth Outcomes

BACKGROUND

Premature/low-birth-weight infants are at significant risk of metabolic diseases in adulthood, which may be related to the levels of fetal adipokine. Here, we investigated the differences in the levels of umbilical cord blood adiponectin, leptin, insulin, and ghrelin in preterm and term infants and sought to elucidate the link between these hormones and fetal growth. We also evaluated the interrelationship among these metabolic hormones in both groups of newborns.

METHODS

A total of 149 mother-infant pairs (100 in the preterm group and 49 in the term group) were enrolled in the study. The preterm group was further subdivided according to birth weight (≤1,500, 1,501-2,000, 2,001-2,500, and >2,500 g), gestational age (<34 vs. ≥34 weeks), and appropriate for gestational age (AGA) vs. small for gestational age (SGA). The general condition of the mothers and the growth parameters of the newborns at birth were recorded.

RESULTS

The levels of adiponectin, leptin, and ghrelin were lower in the preterm group than those in the term group (p < 0.05). In the preterm group, the leptin levels of infants with gestational age ≥34 weeks were significantly higher than those of infants with gestational age <34 weeks (mean ln leptin = 0.63 vs. 0.36 ng/ml, p = 0.009). The levels of adiponectin were lower in the SGA group than those in the AGA group (mean ln adiponectin = 2.26 vs. 2.84 µg/ml, p = 0.001), whereas those of ghrelin displayed the opposite trend (mean ln ghrelin = 6.29 vs. 5.71 pg/ml, p < 0.001). Leptin was significantly correlated with insulin both in preterm infants with birth weight (BW) >2,000 g and in term infants. Umbilical cord blood leptin was positively correlated with the BW, birth length, and head circumference of newborns (r = 0.460, 0.311, and 0.310, respectively, all p < 0.05), whereas ghrelin was negatively correlated with the same parameters (r = -0.372, -0.415, and -0.373, respectively, all p > 0.05).

CONCLUSIONS

The lack of maturation of adipose tissue and the gastrointestinal tract by the fetus due to prematurity is associated with changes in the levels of cord blood adiponectin, leptin, and ghrelin. The dysregulation of these hormones in preterm infants may be a risk factor for fetal growth and future metabolic diseases.

Longitudinal changes in high molecular weight serum adiponectin levels in healthy infants

To determine the factors associated with high molecular weight adiponectin (HMW-ad) levels during the first year of life, the longitudinal changes in serum HMW-ad were investigated from birth to 12 mo of age. The total adiponectin levels, HMW-ad, and leptin were measured longitudinally from birth to 12 mo of age in 56 healthy infants (>or=35 wk of gestation). Serum HMW-ad levels were positively correlated with total adiponectin levels (R2 = 0.93, p < 0.0001). Serum HMW-ad levels at birth, six, and 12 mo were 13.7 +/- 0.9 (mean +/- SE), 13.3 +/- 0.8, and 7.7 +/- 0.5 microg/mL, respectively. The levels at 12 mo were significantly lower than those at birth and 6 mo, respectively. In a multiple regression analysis, the HMW-ad levels at 12 mo were found to be related only to cord blood HMW-ad levels (beta = 0.680, p < 0.001) and not to any other factors. These results imply that postnatal production of HMW-ad at least during infancy may be regulated before birth. Further study is necessary to determine whether cord blood HMW-ad has an effect and whether it is involved in the development of metabolic syndrome.