Endocrine Abstracts

Fetal adipose tissue growth is a coordinated process involving the growth hormone-insulin-like growth factor (GH-IGF) axis. Maternal cold exposure (CE) induced by winter shearing can promote fetal fat growth depending on maternal food. The following study examined the interaction between maternal CE and dietary intake on the mRNA abundance for the endogenous ligand of the GH secretagogue receptor (GHSR-1a), the IGF-I and II receptors and the enzyme glycerol-3-phosphatase (G3P) which has a role in regulating lipolysis.

Twenty-six multiparous ewes of similar body weight were entered into the study, thirteen were shorn (S) at 70 days gestation and thirteen remained unshorn (US), with 7 ewes per group being nutrient restricted (NR) over the final month of gestation, consuming 50% of the intake of controls. All offspring were humanely euthanased at one day of age to enable perirenal adipose tissue sampling. The relative abundances of GHSR-1a and G3P mRNA to 18S rRNA were determined using RT-PCR and are expressed in arbitrary units (a.u.).

Maternal cold exposure resulted in a significant upregulation of mRNA for the GHSR-1a mRNA (S 9.9 plus/minus 3; US 3.2 plus/minus 1 (p<0.01)). Whereas mRNA for the IGF-I and II receptors were unaffected, G3P was reduced (S 2.5 plus/minus 0.2; US 3.9 plus/minus 0.2 (p<0.05). These adaptations in GHSR-1a and G3P were further enhanced in offspring born to CE mothers that were NR. Spearman’s test showed a negative correlation between the GHSR-1a and G3P genes (p<0.001). In conclusion, the anabolic effects of maternal CE on fat deposition in the fetus are partly mediated by increased sensitivity to the GH secretagogue receptor -1a which also has anti-lipolytic effects.