Affiliation(s)
1. Laboratory of Animal Endocrinology and Metabolism, Veterinary Faculty, University of La República, Lasplaces 1550, Montevideo 11600, Uruguay
2. Department of Animal Production and Grazing, Agronomy Faculty, University of La República, Garzón 780, Montevideo 12900, Uruguay
3. Aragon Environmental Research Institute, Department of Animal Production and Food Science, University of Zaragoza, Miguel Servet 177, Zaragoza 50013, Spain
ABSTRACT
The liver is one of the
most important visceral organs, which represents a large contribution to whole animal
energy expenditure and the major synthetic site of insulin-like growth factor-1 (IGF-1) peptide.
Decreased plane of nutrition acts by reducing the metabolic rate and mass of metabolic
tissues, such as liver. Also, undernutrition results in the reduced circulating
IGF-1 concentrations, due to the uncoupled growth hormone-IGF (GH-IGF) axis. This study
investigated whether a 22-day period of undernutrition (half maintenance) could
affect liver mass and IGF-1 protein and gene expression. Sixteen pregnant ewes
fed all (n = 9) or half (n = 7) of their maintenance
energy requirements were slaughtered on day 7 of pregnancy (oestrus = day 0). Body and
liver mass, IGF-1 plasmatic concentrations and liver IGF-1 mRNA and protein
expression were determined. Liver mass and the proportion of liver mass to empty
body weight were lower in underfed animals. While IGF-1 plasmatic
concentrations were lower in undernourished ewes, no differences in liver mRNA
expression were found. This is the first time that differences in immunohistochemistry
intensity and total content are reported in sheep. In
summary, the decreased plasma IGF-1 concentrations induced by undernutrition in
ewes was not associated with its reduced hepatic mRNA or protein expression,
but to a decrease in liver mass.
KEYWORDS
Undernutrition, insulin-like
growth factor-1, liver mass, sheep.
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