TABLE 2.

Fructose exposures in animal models

Model-system	Dose	Exposure duration	Methods	Key findings	References
Reactive species formation
Male Wistar rats	High-fat diet and 5% fructose in drinking water per day	4 months	ROS in kidney measured DCFDA; MDA measured spectrophotometrically	ROS and malondialdehyde expression were elevated in the kidneys	Rosas-Villegas et al., 2017
Male C57BL/6 mice	10% fructose in drinking water per day	20 weeks	Total ROS activity assay kit	80% increase in ROS production; increased mitochondrial hydrogen peroxide production	Zhang et al., 2016
Male Sprague–Dawley rats	10% fructose in drinking water per day	8 weeks	Total ROS measured by DCFDA	Increased ROS, MDA, XO, iNOS, and hydrogen peroxide levels in rat livers	Zhang et al., 2015
Male HTG rats, male Wistar rats, and male Lewis rats	10% fructose in drinking water per day	3 weeks	Pentosidine measurement- fluorescence at 332ex/378em nm	Increased post-translational pentosidine levels in rat aorta and skin samples for all three strains of rats	Mikulikova et al., 2008
Male Wistar rats (mononuclear cells)	10% fructose in drinking water per day	12 weeks	ROS measured using flow cytometry to quantify the production of *O2−, H2O2, NO and *ONOO−/*OH−, with DHE, DCF, DAF-2 T in peripheral blood and bone-marrow mononuclear cells	Elevated level of ROS generation in peripheral blood mononuclear cells; no ROS increase in bone marrow mononuclear cells	Porto et al., 2015
Male Fischer rats	20% fructose in drinking water per day and high salt diet (8%) for last 10 weeks	20 weeks	ROS production quantified using DCFDA; SOD activity measured by autooxidation of pyrogallol; cat activity was measured spectrophotometrically	Salt-dependent hypertension and elevated oxidative stress; decrease in renal enzymatic SOD and catalase activity in the kidney	Dornas et al., 2017
Male and female Sprague–Dawley rats	20% fructose water solution per day	Dose received during gestation and lactation periods	OxiSelect in vitro ROS/RNS assay kit	1.5-fold increase in hippocampal LPO which is associated with elevated ROS	Yamada et al., 2019
Male Wistar rats	250 mL of 25% fructose drinking water per day with 40.6% fats	6 weeks	ROS levels measured by DCFDA	8-time increase in lipid peroxidation levels in mitochondria for fructose groups and high fat and fructose groups; no increases in ROS for fructose-treated groups	Garcia-Berumen et al., 2019
Male Sprague–Dawley rats	30 g of fructose per 100 g of chow (30% fructose)	8 weeks	DNA/RNA oxidative damage ELISA assay	8-OHdG levels were increased indicating elevated levels of oxidative stress	Cioffi et al., 2017
Male C57BL/6 mice	60% fructose diet per day	6, 10, and 20 weeks	Superoxide production determined through measurement of NADPH activity	Significant increase in superoxide production in mice during 6 weeks of intake; at 10 weeks, there was a 29% increase in superoxide production, and at 20 weeks, there was a 16% increase	Mellor et al., 2010
Male Wistar rats	Fructose content provides 60% of calories in diet per day	2 weeks	Measured through insulin resistance	Inhibited expression of catalase in the heart and liver; condition leads to a high vulnerability to elevated levels of oxidative stress in insulin resistance	Cavarape et al., 2001
Male spontaneously hypertensive rats	60% fructose	3 weeks	ROS by flow cytometry using the fluorescence dye DHE	There were high levels of ROS accumulation and lipid peroxidation in rostral ventrolateral medulla; development of brain oxidative stress can lead to hypertension	Wu et al. 2017
Male Wistar rats	60% fructose chow in diet per day	12, 16, 20, and 24 weeks	MDA measured spectrophotometrically	Increase in production of substances such as methylglyoxal, which leads to muscle oxidative stress; no significant increase in the levels of the peroxidation product malondialdehyde in the serum, left ventricular tissue, or in the cardiac level of the nitrooxidative marker 3-nitrotyrosine	Szucs et al. 2019
Mitochondrial and metabolic dysfunction
Male C57BL/6 mice	10% fructose in drinking water per day	20 weeks	Oxygen consumption rates monitored by a Seahorse XF24 oxygen flux analyzer; complex II enzyme activity measured using microplate assay kit	Cardiac hypertrophy, diastolic dysfunction, decreased complex II activity by 60%, and reduced state III and IV OCR; for complex I and II, rates of ATP synthesis decreased by 37% and 36% respectively	Zhang et al., 2016
Male Sprague–Dawley rats	10% fructose in drinking water per day	6 weeks	Respiratory measurements made using Oroboros system for permeabilized muscle fibers	In the extensor digitorum longus (EDL) muscle, there was a significant decrease in complex I respiration; respiratory activity for other complexes were similar; for the soleus muscle, OXPHOS capacity for complex II was much lower	Warren et al., 2014
Male Wistar rats	250 mL of 25% fructose drinking water per day	6 weeks	Mitochondrial respiration obtained by determining the oxygen consumption rate of isolated mitochondria using a Clark-type electrode coupled to a YSI 5300A biological oxygen monitor	Mitochondrial respiratory rate in state 3 decreased in the fructose group by 1.6-fold; 1.8-fold increase in state 4 respiration; complex I activity decreased ~2.3-fold in mitochondria for the high fructose group	Garcia-Berumen et al., 2019
Male Sprague–Dawley rats	30 g of fructose per 100 g of chow (30% fructose)	8 weeks	mtDNA damage measured using qPCR; changes in mitochondrial biogenesis monitored through the expression of Pcg1α, Nrf1, and Tfam	Increase in mtDNA damage in the liver of rats; 22% decrease in mtDNA fragments; mitochondrial copy number was reduced by approximately 56%; reduced mitochondrial biogenesis	Cioffi et al., 2017
Male and female Sprague–Dawley rats	20% fructose water solution per day	Dose received during gestation and lactation periods	Mitochondria oxygen consumption rate- MitoXpress oxygen consumption assay; mtDNA damage assessed using qPCR	Reduction mitochondrial OCR; no change in mtDNA amount	Yamada et al., 2019
Transcriptional changes
Male Wistar rats	High-fat diet and 5% fructose in drinking water per day	4 months	Protein expression measured by immunoblotting	Increased protein expression of inflammatory markers Tlr-4, Nf-κb; Tnfα/β, and Mcp1	Rosas-Villegas et al., 2017
Kupffer cells from male Sprague–Dawley rats	10% fructose in drinking water per day	8 weeks	mRNA expression measured using qPCR	Increase in Txnip, Nlrp3 levels in Kupffer cells, and aggravate oxidative stress in livers; in vitro fructose exposure did not change levels of Txnip, Nlrp3, and no ROS overproduction; increased co-localization of Nlrp3;	Zhang et al., 2015
Male Sprague–Dawley rats	30 g of fructose per 100 g of chow (30% fructose)	8 weeks	mRNA expression measured using qPCR; protein expression measured by immunoblotting	Pgc1α, Nrf1, and Tfam reduced expression by 19%, 41%, and 43% respectively	Cioffi et al., 2017
Male C57BL/6 mice	10% fructose in drinking water per day	20 weeks	mRNA expression measured using qPCR; protein expression measured by immunoblotting	Decreased CFTR expression and induced ROS and oxidative stress	Zhang et al., 2016
Male Sprague–Dawley rats	10% fructose in drinking water per day	6 weeks	Protein expression measured by immunoblotting	Decline in Pgc-1α protein levels in both EDL and soleus muscles; increased Sirt3 protein levels in the soleus, and decline in the EDL; no changes in thioredoxin reductase-2 protein levels in the soleus, but there was a decrease in the EDL muscle	Warren et al., 2014
Male Wistar rats	10% fructose in drinking water per day	12 weeks	Annexin V-FITC apoptosis detection kit; cytokines measured in the plasma by flow cytometry using a Cytometric bead Array – Mouse inflammation kit	Elevated rates of apoptosis; Il-6 and Il-12p70 were higher	Porto et al., 2015
Male and female Wistar rats	10% fructose in drinking water per day	24 weeks	mRNA expression measured using qPCR	Increased expression of Irβ, Irs-1, Irs-2, Akt, Pi3k, eNOS, mTor, Ppary, Nrf2, and eNOS; induction of proinflammatory markers, iNOS, Tnfα, Il-1β, Il-18, MDA, and ALT, as well as anti-inflammatory factors Il-10, and Nrf2 in adipose tissues of male and female rats	Pektas et al., 2016
Male and female Sprague–Dawley rats	20% fructose water solution per day	Dose received during gestation and lactation periods	mRNA expression measured using qPCR; protein expression measured by immunoblotting	Decreased Ucp5 and Tfam; the amount of genomic Nadh dehydrogenase 1, 2, and 3 did not change; no alterations in mitochondrial complex protein expression	Yamada et al., 2019
Male Wistar rats	Fructose content provides 60% of calories in diet per day	2 weeks	mRNA expression assessed by northern blot	Decreased expression of Cat and Sod1 in the liver and Cat in the heart; reductions in catalase (cat) and cu-ZnSOD1 activity were detected in skeletal muscle and adipose tissues	Cavarape et al., 2001
Male C57BL/6 mice	60% fructose diet per day	6, 10, and 20 weeks	mRNA expression measured using qPCR	No effect on thioredoxin-2 gene expression level; at 6 weeks of exposure, β-myosin gene expression remained unchanged; at 10 weeks, non-significant mRNA expression levels of β-myosin, and NADPH oxidase subunit, Nox2 by 16.8-fold; at 20 weeks, gene expression levels of β-myosin was lowered, and Nox2 was similar for the control and fructose-treated groups	Mellor et al., 2010
Male Wistar rats	60% fructose chow in diet per day	24 weeks	mRNA expression measured using qPCR; myosin 6 protein level determined by proteomics	Myosin 6 protein level was increased after fructose intake; Elovl6 and Myh6 also increased; Creatine kinase, creatine kinase-MB, and lactate dehydrogenase levels were not significantly different; 45% decrease in cardiolipin	Szucs et al. 2019
Spontaneously hypertensive rats	60% fructose	12 weeks	Protein expression measured by immunoblotting	NADPH oxidase subunit gp91phox and angiotensin II type I receptor levels increased in the RVLM neuron and there was a decrease in extracellular SOD expression	Wu et al. 2017