Metabolic memory determines gene expression in liver and adipose tissue of undernourished ewes

Abstract

The aim of this work was to determine the effects of undernutrition on gene expression in liver and adipose tissue, and on the hepatic concentration of insulin like growth factor 1 (IGF1) and insulin, in pregnant ewes with different initial body condition score (iBCS). Thirty-six Rasa Aragonesa ewes were divided into 2 groups with different BCS: BCS > 2.75 (n = 19; high, H) and BCS < 2.25 (n = 17; low, L), and were randomly assigned to two nutritional treatments: 1.5 (control, C) or 0.5 (undernourished, U) times the daily maintenance requirements. Thus, the final four groups were: high-iBCS control (HC, n = 9), high-iBCS undernourished (HU, n = 10), low-iBCS control (LC, n = 9) and low-iBCS undernourished (LU, n = 8). High-iBCS ewes presented greater liver IGF1 mRNA expression (P < 0.05), which is consistent with higher liver IGF1 and insulin concentrations (P = 0.10 and P < 0.05, respectively), and with greater liver growth hormone receptor (GHR) gene expression (P < 0.05). These data, and the trend for more leptin receptor type b (LEPR-b) mRNA in high-iBCS ewes (P = 0.09) suggest a better anabolic status. Furthermore, undernourished ewes presented lower hepatic insulin like growth factor binding protein 3 (IGFBP3) gene expression (P = 0.05), suggesting a shift in the availability of IGFs in plasma and therefore, in their action in target tissues. In the adipose tissue, U ewes presented lower GHR mRNA expression than C animals (P < 0.05), being greatest in the high-iBCS control group. As expected, leptin (LEP) gene expression in adipose tissue was greater in high-iBCS than in low-iBCS ewes (P < 0.05). Nevertheless, the most interesting finding was the organ-specific pattern of LEPR-b gene expression: in contrast to the liver, the greatest adipose tissue LEPR-b gene expression was observed in the low-iBCS undernourished ewes (P < 0.05). In summary, the present study demonstrates that the initial body condition score evokes different, even contrasting, responses in key metabolic organs (i.e., liver and adipose tissue) of control and undernourished ewes.