Novel Biomarker Establishment for Evaluation of Excessive Fructose Consumption Using a Rat Model

Abstract

Background/Aim: The habitual consumption of excessive fructose is associated with the onset and progression of lifestyle-related diseases, such as nonalcoholic fatty liver disease (NAFLD). In this study, we investigated the physiological changes observed when consuming a diet containing excessive fructose on the viewpoints of hepatotoxicity biological markers using a rat model and explored the biomarker candidates that could detect the effects of excessive fructose intake at an early stage. Materials and Methods: Male rats were fed 63% high fructose diet (HFrD) ad libitum and their blood samples were collected before and at 1, 2, 3, and 4 weeks after allocation. The plasma biochemical parameters, hepatotoxic enzyme activities including alkaline phosphatase (ALP) isozymes were analyzed. Results: HFrD consumption for 4-weeks created NAFLD-like symptoms, including elevated plasma lipid parameters and hepatotoxicity markers, as well as fat accumulation in the liver compared with rats consuming a control diet. Alanine aminotransferase (ALT) and glutamate dehydrogenase (GLDH) were increased from the 3 rd and 2 nd weeks, respectively, but no changes were observed on ALP activity. However, the daily consumption of the HFrD increased the plasma activities of liver-type ALP isozyme, and decreased plasma small intestinaltype ALP isozyme soon after the start of feeding. Conclusion: ALP isozyme analysis in combination with GLDH and ALT activities in the plasma samples could be a useful tool to detect the physiological changes induced by excessive fructose intake at an early stage of the development of NAFLD.

Active-phase Plasma Alkaline Phosphatase Isozyme Activity Is a Sensitive Biomarker for Excessive Fructose Intake

“…Given that NAFLD is asymptomatic (24), we must take appropriate action to ensure that individuals avoid daily excessive fructose intake, and develop effective tools to diagnose daily excessive fructose intake. Our previous study demonstrated that four weeks of HFrD consumption in rats caused hepatic hypertrophy with lipid accumulation, as well as a significant increase in L-ALP activity and a significant decrease in I-ALP in the blood (11). I-ALP activity decreased from the first week of HFrD in vivo 37: 1967-1974 (2023) 1970…”

“…Animals and housing environments. In our previous study in sixweek-old rats, we measured the activity of ALP isozymes in blood collected during the light period (sleep phase) after four weeks of HFrD feeding (11). The purpose of this study was to evaluate whether variations in ALP isozyme activity occurred between the light (sleep) and dark (active) periods after 1 week of consuming a HFrD.…”

“…Experimental design. After four weeks of acclimatization, two groups of male rats aged six weeks, which had been handled daily at ZT2-4 or ZT14-16, were randomly divided into two groups, as previously described (11): one group continued consuming the CD, and the other began consuming a 63% HFrD (D21012001, Research Diets, Inc.). The detailed composition of the CD and HFrD is shown in Table I.…”

“…To the best of our knowledge, there is no optimal method to identify fructose overdose prior to the onset of NAFLD. Therefore, in our previous study, we evaluated and compared the physiological changes that occurred in rats fed an excessively high-fructose diet (HFrD) versus a control diet for four weeks, with a focus on hepatotoxicity biomarkers (11). We found that the activities of two alkaline phosphatase (ALP) isozymes, liver-type-ALP (L-ALP) and small intestinal-type ALP (I-ALP), were useful indicators for detecting physiological changes caused by excessive fructose consumption in the early stages of NAFLD and, ultimately, the development of metabolic syndrome.…”

“…In the present study, we used the rat model described in our previous study (11) to evaluate blood parameters collected during the sleep and active phases after one week of excessive fructose intake.…”