Endocrine Abstracts

Uncoupling protein-2 (UCP2) has many postulated functions, including possible solute exchange and immunity within the neonatal lung. The effect of maternal nutrition during late gestation on UCP2 abundance in the ovine neonatal lung has not been determined.

Twin-bearing ewes of similar age and body weight were individually housed from 110 days gestation. Six controls (C) were fed and consumed 100% of their energy requirements for maintenance and growth of the conceptus, while the nutrient-restricted (NR) group received 60% of this amount, until term 147 days, when they all gave birth spontaneously at term. At 6 hours of age, one twin was randomly selected and humanely euthanased to allow tissue sampling. The remaining twin was sampled at 30 days of life. Total lung RNA was extracted, reverse transcribed and UCP2 mRNA abundance measured by RT-PCR using oligonucleotide primers designed specifically to ovine UCP2. Results are given as means and standard errors in arbitrary units, as a ratio of 18S rRNA and are expressed as a percentage of a reference sample. Differences between groups were analysed by Mann-Whitney U test.

Lung fresh and dry weights, and total protein concentration were similar between the groups and increased with postnatal age. UCP2 mRNA levels were higher at 6 hours of age compared to 30 days. UCP2 mRNA was increased in the NR groups at both 6 hours (C 115.8 plus/minus 3.4; NR 135.7 plus/minus 2.6, p<0.01) and 30 days (C 13.4 plus/minus 0.8; NR 32.5 plus/minus 1.4, p<0.01) in the lung.

The peak in UCP2 mRNA abundance at 6 hours of age in the neonatal lung may be important in establishing solute exchange and independent breathing. The increased abundance of UCP2 mRNA with NR in late gestation may indicate an underlying susceptibility to infection.