Endocrine Abstracts

Background: Size at birth has been shown to have important consequences on later health, including the development of the metabolic syndrome. Tissue sensitivity to cortisol is regulated, in part, by the GCR and alterations in GCR expression have been observed in obesity and type 2 diabetes.

Objectives: To examine whether birth weight influences the expression of GCR mRNA in skeletal muscle (SM) at days 7 and 14 of postnatal life.

Methods: Piglets from eleven litters were ranked according to weight at birth and three from each litter were assigned to small (S; n=11), normal (N; n=11) or large (L; n=11) groups. Animals were humanely euthanased on either day 7 (n=15) or 14 (n=18) of age and SM was sampled. GCR expression was quantified by real-time PCR. Results are expressed as mean values and standard errors normalised to 18S. Plasma non-esterfied fatty acids (NEFA) were assessed using colorimetric assay.

Results: On day 7 there was no effect of birth weight on GCR expression. By day 14, N pigs had significantly higher GCR expression than both S and L pigs (S, 0.2±0.08; N, 0.8±0.1; L 0.3±0.1 (P<0.05)). On day 14 only, a positive relationship between GCR and NEFA was observed in N and L pigs, conversely, S pigs exhibited a negative relationship (P<0.05).

Conclusion: Altered expression of GCR in SM between normal and both small and large offspring on day 14 indicates alterations in cortisol sensitivity. Furthermore, the relationship observed between GCR and NEFA suggests altered regulation of lipids in the S piglets. Further studies are required to investigate whether these changes persist into adulthood.