Fasting and sampling time affect liver gene expression of high-fat diet-fed mice

Abstract

Several physiological and biological variables are known to affect peroxisome proliferator-activated receptor (PPAR)-adependent signaling pathway and plasma biochemical profiles. However, less is known about the effect of these variables on high-fat diet-fed mice. In a 5-week study, C57BL/6 mice were divided into control (C) and high-fat diet-fed (H) groups, whereby before dissection, each group was subdivided into non-fasted (nC and nH) and a 15-h fasted mice (fC and fH) killed in the early light cycle, and a 15-h fasted mice (eC and eH) killed in the late phase of the light cycle. Liver and blood from the vena cava were collected. Non-fasted nC and nH mice have a marginal difference in their body weight gain, whereas significant differences were found for fasted mice. In nH mice, PPAR-a, acyl-CoA oxidase and insulin-like growth factor-binding protein expressions were significantly elevated, in contrast to fatty acid synthase (Fasn), stearoyl CoA-desaturase (SCD)-1, and elongase (ELOVL)-6 expressions. Fasn was profoundly induced in fH mice, while decreased sterol regulatory-binding protein-1 and SCD-1 were found only in eH mice. Different from the gene expression profiles, plasma total cholesterol level of the eH mice was higher than controls, whereas nH mice have increased plasma non-esterified fatty acids. Only glucose level of the fH mice was higher than that observed for controls. Results showed that fasting and sampling time have significantly affected liver gene expression and plasma biochemical indices of the high-fat diet-treated mice. An overlook in these aspects can cause serious discrepancies in the experimental data and their interpretations.

Thousands of oscillating LncRNAs in the mouse testis

“…Intriguingly, although the 12-time-point dataset and six-time-point control dataset shared the same 5964 lncRNAs, the number of rhythmically expressed lncRNAs in each dataset differs significantly. In particular, the 12-point-time dataset has 44 more rhythmically expressed lncRNAs than the six-time-point control dataset, which could be due to the differing sampling strategies [62] , [63] . However, 46 lncRNAs are rhythmically expressed under both the 12-time-point and six-time-point conditions ( Supplementary Tables 25 and 26 ).…”

“…Sixth, despite the 12-time-point dataset and six-point control dataset sharing the same number of 5964 lncRNAs, we identified 44 more rhythmically expressed in the 12-time-point dataset than in the six-point control dataset. As differing sampling strategies [62] , [63] can affect the expression profiles, additional studies are required to validate the effects of sampling on the outcomes of the rhythmicity analysis. Seventh, although the computational tools helped predict GO and KEGG pathway annotations of these rhythmically expressed mouse testicular lncRNAs, these predictions require experimental validations.…”