Effect of starvation on activities and mRNA expression of lipoprotein lipase and hormone-sensitive lipase in tilapia (Oreochromis niloticus × O. areus)

Abstract

A 4-week study was conducted to determine the effect of starvation on activities and mRNA expression of lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) in hybrid tilapia (Oreochromis niloticus x O. areus). The tissue samples were sampled once a week. Results showed that body weight (BW) and hepatosomatic index (HSI) were decreased significantly (P < 0.05) during starvation. The percentages of crude fat and crude protein in the whole body and the fat content in muscle decreased significantly (P < 0.05), while the rate of moisture and crude ash increased significantly (P < 0.05). The response of LPL, HSL activities and mRNA expression in tissues was tissue dependent. The activities of LPL and HSL in muscle at day 7 were elevated by 2.5 times (P < 0.05) and 11.8 times (P < 0.05) of the value at day 0, respectively, and both then decreased to pre-starvation levels at day 14 and finally stabilized at a certain level afterward. LPL and HSL mRNA abundance in muscle remained relatively stable between 0 and 14 day; then, a significant increase was seen after 14 days. In the liver, LPL activity maintained a significantly increasing trend during starvation, while HSL activity rose dramatically at day 7 of starvation by 2.35 times (P < 0.05) and finally stabilized at a certain level. The mRNA abundance of liver LPL increased significantly during the whole process of starvation (P < 0.05), whereas the mRNA abundance of liver HSL decreased significantly at day 7 of starvation, elevating significantly afterward (P < 0.05).

Changes in activities and mRNA expression of lipoprotein lipase and fatty acid synthetase in large yellow croaker,Larimichthys crocea(Richardson), during fasting

“…Similar findings were reported in tilapia ( Oreochromis niloticus × O. aureus ) (Han et al . ). Muscle fat content was the most important attribute of flesh quality (Johansson, Kiessling, Kiessling & Berglund ).…”

“…Fasting also regulated the enzyme activities (Furné, García‐Gallego, Carmen Hidalgo, Morales, Domezain, Domezain & Sanz ; Abolfathi, Hajimoradloo, Ghorbani & Zamani ) and gene expressions in different tissues of fish (Han et al . ; Tian, Wen, Zeng, Jiang, Wu, Liu & Yang ). However, the mechanism of lipid metabolism has not yet fully elucidated in large yellow croaker when faced with fasting.…”

“…; Albalat, Saera‐Vila, Capilla, Gutiérrez, Pérez‐Sánchez & Navarro ), fasting (Han et al . ; Tian et al . ), re‐feeding (Oku et al .…”

Adropin induction of lipoprotein lipase expression in tilapia hepatocytes

“…In these experiments, the increase in LPL production also occurred with parallel rises in LPL gene expression, suggesting that adropin can not only induce LPL release but also trigger LPL synthesis via up-regulation of LPL gene expression. Previous studies pointed to the effect of LPL on lipid metabolism in tilapia (Oreochromis niloticus) in which hepatic LPL gene expression levels were synchronously increased after fasting (Han et al 2011, Tian et al 2013, and further, there was a negative correlation between TG levels and LPL levels (Tian et al 2013), suggesting LPL is an important lipolytic factor in tilapia. In mice, hepatic adropin gene expression is regulated by liver X receptor (LXR)-a (Kumar et al 2008), which is a nuclear receptor involved in cholesterol and triglyceride metabolism (Kalaany & Mangelsdorf 2006).…”

“…Liver LPL targets circulating TG to the liver and increases ketone body production, which can be used as energy as an alternative to glucose (Merkel et al 2002). The regulations of LPL expression in fish were reported to be affected by various factors, including, but not limited to, hormones (Albalat et al 2007, fasting (Oku et al 2006, Han et al 2011) and feeding conditions (Oku et al 2006, Benedito-Palos et al 2013. Additional studies of LPL expression in the piscine liver will further our understanding of the mechanisms controlling hepatic lipid regulation and the formation of fatty liver.…”