Dietary lipids affect growth, body composition, digestive enzyme activities and mRNA levels of somatic growth-regulating genes in pejerrey (Odontesthes bonariensis)

GOMEZ-REQUENI P; BEDOLLA-CÁZARES F; TOLEDO-CUEVAS M; CANOSA LF

Barcelona

Congreso; 17 International Congress of Comparative Endocrinology; 2013

This study aimed to determine the growth performance, body composition, digestive enzyme activities and mRNA levels of growth hormone receptors (GHRs), insulin-like growth factors (IGFs) and muscle growth biomarkers myostatin (MSTN) and myogenin (MyoG) in pejerrey (Odontesthes bonariensis). Juvenile pejerrey were fed with graded levels of dietary lipids (L):6%, 10% and 25%. Following a 14-week trial, body weight and weight-gain were higher with L10 and L25. Body lipids reserves increased along with dietary lipids, while nitrogen and energy retentions were higher in L10 and L15. Muscle fatty acid composition was differentially regulated by the diets with the exception of EPA, DHA and n-3 PUFA content. The total activity of neutral lipase was stimulated in the L25 group whereas the specific activity of pancreatic lipase decreased in this same group. L6 treatment showed the lowest total activity of alkaline proteases, and the L10 group showed the highest total activity of trypsin. The specific activity of amylase decreased in the L25 group. Liver IGF-I mRNA levels decreased in groups L10 and L25. Muscle IGF-I gene expression slightly increased in groups L10 and L25 whereas GHR-I decreased in the L10 group. GHR-II, IGF-II and MyoG mRNA levels increased in the L6 goup. In the adipose tissue, a decrease of IGF-I mRNA levels was evident in the L10 group, whereas GHR-I, IGF-II and GHR-II mRNA levels were not modified. All together, it seems clear that 25% of dietary lipids does not have additional stimulatory effects on the digestive proteases activity compared to 10%, but negatively affects pancreatic lipase and trypsin activities. Moreover, the L10 group shows a particularly fine tuning of the GH/IGF system, suggesting that 10% of dietary lipids would be enough to support the growth of pejerrey in captivity. Grants: PICT10-1493, PIP0271 to FC and 2007-83920 CONACyT, 2012 CIC-UMSNH to MT-C.