Presented at the Neonatal Society 2001 Autumn Meeting.

Bispham J¹, Dandrea J¹, Mostyn A¹, Brameld JM², Buttery PJ², Stephenson T¹, Symonds ME¹

¹ Academic Division of Child Health, School of Human Development, University Hospital, Nottingham, NG7 2UH, UK
² Division of Nutritional Biochemistry, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK

Introduction: Leptin and insulin-like growth factor (IGF)-I acting through class I cytokine receptors, and the growth hormone receptor (GHR) regulate fetal growth and development and may also control adipose tissue deposition. It is not known, however, whether maternal nutrition programmes adipose tissue deposition or the mRNA abundance of cytokines and their receptors. The aim of the current study was to determine whether manipulating maternal nutrition during early to mid gestation impacts on the abundance of mRNA species for leptin, IGF-I or GHR.

Methods: Thirteen singleton-bearing ewes of similar body weight and parity were entered into the study. Seven ewes were provided with 60% of their total energy requirements for body weight and pregnancy from 28 to 80 days (i.e. nutrient restricted (NR)) gestation whilst the remainder were fed ad libitum feeding (i.e. well fed (WF)). After 80 days gestation, all ewes were provided with 150% of their total energy requirements for body weight and pregnancy until term. Then between 140 and 145 days gestation (term = 148 days) all ewes were euthanased with an overdose of barbiturate (100 mg kg-1 pentobarbital sodium: Euthatal). Total RNA was extracted from perirenal adipose tissue. Leptin mRNA abundance was determined by RT-PCR, using oligonucleotide primers specific to ovine leptin (Genbank Acc: U62123) (forward 5′-CAC CAA AAC CCT CAT CAA GAC G-3′ and reverse 5′-ACA TTT CTG GAA GGC AGA CTG G-3′) which generated a 192bp product. Both IGF-I and GHR were measured using RNase protection assays as described by Brameld et al (2000). Results are expressed in arbitrary units as a ratio of 18S rRNA internal control. Statistical analysis was performed using Mann Whitney.

Results: Maternal nutrient restriction (28-80 days) followed by re-feeding results in a significant increase in the abundance of leptin mRNA (P=0.005) and adipose tissue deposotion (P<0.05). The same maternal nutritional challenge however results in a decrease in the mRNA abundance of both IGF-I and GHR (P=0.08 and 0.02 respectively, see table 1).

Conclusion: These results confirm that maternal nutrition during early-mid gestation (28-80 days) is capable of programming expression of certain genes. This results in decreased expression of IGF-I and GHR mRNA’s whereas leptin mRNA expression and adipose tissue weight increase. The extent to which this may reprogramme adipose tissue growth in later life remains to be determined.

References
1. Brameld JM, Mostyn A, Dandrea J, Stephenson TJ, Dawson JM, Buttery PJ, Symonds ME Journal of Endocrinology. (2000). 167. 429-437.