NEONATAL SOCIETY ABSTRACTS
Intramyocellular lipid deposition in young adults born <33 weeks gestation
Presented at the Neonatal Society 2009 Autumn Meeting (programme).
Parkinson JR1, Thomas EL2, Hyde MJ1, Doré CJ3, Bell JD2, Modi N1
1 Section of Neonatal Medicine, Division of Medicine, Chelsea and Westminster Campus,
Imperial College London, UK
2 Metabolic & Molecular Imaging Group, MRC Clinical Sciences Centre, Imperial College London, UK
3 MRC Clinical Trials Unit, London, UK
Introduction: Preterm birth is a risk factor for later insulin resistance but the biological determinants are unknown. We have shown that preterm (PT) babies at term (T)(1,2), and young adults born PT, when compared with T subjects (ESPR 2009), have increased abdominal internal (visceral) adipose tissue and intrahepatocellular lipid (IHCL), each a strong predictor of insulin resistance. Here we extend our exploration of the metabolic consequences of preterm birth to address intramyocellular lipid (IMCL) deposition in PT and T young adults.
Methods: The study received Research Ethics Committee approval. We recruited healthy volunteers employing 1H magnetic resonance spectroscopy to determine lipid content in the tibialis (T-IMCL) and soleus muscles (S-IMCL). We examined the effects of gestation (GA), sex and gestation-sex interaction on IMCL (STATA 10.1). Values are mean (SD) or mean difference (95%CI); S-IMCL and T-IMCL are shown as geometric mean and ratio.
Results: We have studied 48 subjects aged 19-27y (PT: GA 29.4 (2.6) wk, BW 1.366 (0.4) kg); T: GA 40.1 (1.6) wk, BW 3.339 (0.4) kg). There were no preterm-term differences in weight (mean diff -1.7 kg (-6.8, 3.4), p=0.5), height (-0.02 m (-0.06, 0.03), p=0.4), BMI (-0.1 kg/m2 (-1.6, 1.4) p=0.9) or waist-hip ratio (0.02 (-0.01, 0.05), p=0.2). Women were significantly lighter (-15.9 kg (-21.0, -10.8), p<0.001) and shorter (-0.12 m (-0.16, -0.07), p<0.001) than men with a lower BMI (-2.3 kg/m2 (-3.8, -0.8), p=0.004), a smaller waist-hip ratio (-0.09 (-0.12, -0.06), p<0.001) and higher T-IMCL (1.3 (1.0, 1.7), p=0.05). When compared with the term group, the PT subjects showed elevated T-IMCL (1.3 (1.0, 1.7), p=0.03) but not S-IMCL (1.0 (0.8, 1.3), p=0.9). There was no evidence of an interaction between gestation and sex in any variable.
Discussion: Soleus and tibialis muscles differ in their fibre type. Physical fitness, age and other factors governing relative IMCL deposition remain imperfectly understood. Nonetheless several studies report an association between IMCL and insulin resistance. Our observation of elevated T-IMCL in young adults born preterm may be a factor influencing the metabolic derangements found in this population and adds to our growing understanding of the potential biological pathways influencing adult metabolic health following preterm birth.
1. Uthaya et al Pediatr Res 1995 57:1-6
2 Thomas et al Arch Dis Child Fetal Neonatal Ed 2008 93:F382-3