Endocrine Abstracts

Introduction: Maternal dexamethasone (DEX) treatment is known to promote thermoregulation in the newborn lamb by increasing the amount of uncoupling protein 1 (UCP1). The extent to which the IGF axis within adipose tissue (AT) may be altered following such treatment is not known.

Methods: Eight triplet bearing ewes were entered into the study, 5 of which were injected with 16 micrograms of DEX at 138 days of gestation (term = 147 days). Caesarean section delivery was performed on the DEX treated ewes at 140 days gestation and at 146 days on the remaining ewes. One lamb from each ewe was immediately killed as a fetus to enable AT sampling and the remaining lambs were delivered into either a warm (30degC) or cool (15degC) ambient temperature. AT was then sampled at 6h of life. Oligonucleotide primer sets for each gene of interest were then designed for use in RT-PCR.

Results: Maternal DEX treatment resulted in significantly less IGF-I mRNA expression (C: 287.7 plus/minus 11.0; D: 238.1 plus/minus 23.1 a.u. (P< 0.05)) in the cool delivered offspring. A similar non-significant trend was apparent in the expression of IGF-II mRNA (C: 57.2 plus/minus 8.4; D: 42.2 plus/minus 5.5 a.u.). Both IGF-I and -II receptors remained unchanged by maternal dexamethasone administration.

Conclusion: Maternal DEX administration was associated with reduced mRNA abundance of IGFI and II in the absence of any change in receptor. This may contribute to altered rates of AT deposition in later life.