Endocrine Abstracts (2003) 6 P18

EFFECT OF MATERNAL NUTRIENT RESTRICTION DURING LATE-GESTATION ON THE HEPATIC INSULIN-LIKE GROWTH FACTOR (IGF) SYSTEM IN NEONATAL SHEEP

MA Hyatt, D Walker, T Stephenson & ME Symonds


Academic Division of Child Health, University of Nottingham, Nottingham, UK.


Maternal nutrient restriction (NR) during late-gestation can influence liver growth by altering maturation of the hypothalamus. Maternal NR during late-gestation increases fetal plasma GH levels whilst circulating IGF-I and IGF-II levels decrease. This study aimed to determine whether maternal NR during late-gestation altered the hepatic IGF system in resultant offspring.

Fourteen primiparous twin pregnant Border Leicester cross Swaledale ewes were fed ad libitum up to 110 days gestation. Six control (C) ewes were fed 12.7 MJ/day whilst NR ewes consumed 9.1 MJ/day. Ewes spontaneously lambed at term, and one twin was humanely euthanased at 1 day and the remaining twin at 30 days of age to enable tissue sampling. The relative abundance of hepatic IGF-IR and IGF-IIR to 18S rRNA was measured by RT-PCR. Results are given as means and SEM in arbituary units (a.u.) and expressed a percentage of a reference sample. Significant differences were analysed using a Mann-Whitney U-test (p < 0.05).

Maternal NR over the final month of gestation had no effect upon lamb body or liver weight at 1 day of age. However, NR offspring sampled at 30 days had a higher liver to body weight ratio compared to controls (C 0.061 plus/minus 0.01; NR 0.76 plus/minus 0.01 g/kg, p = 0.034). Hepatic IGF-IR (C 74.43 plus/minus 12.8; NR 36.9 plus/minus 10.0 a.u.) and IGF-IIR (C 124.1 plus/minus 26.8; NR 48.0 plus/minus 15.3 a.u.) mRNA abundance was significantly down-regulated in NR offspring at 1 day (p < 0.05) but not 30 days of age.

Nutritional down-regulation of IGF-IR and IGF-IIR at 1 day of age occurred in the absence of changes in lamb body or liver weight. However, altered IGF receptor levels may have contributed to the increased liver size relative to whole body weight observed in NR offspring at one month of age.

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