Abstract
BackgroundCanola oil shortens the life span of stroke-prone spontaneously hypertensive (SHRSP) rats compared with rats fed soybean oil when given as the sole dietary lipid source. One possible mechanism leading to the damage and deterioration of organs due to canola oil ingestion is oxidative stress. This study investigated the effect of canola oil intake on oxidative stress in this animal model.MethodMale SHRSP rats, were fed a defatted control diet containing 10% wt/wt soybean oil or a defatted treatment diet containing 10% wt/wt canola oil, and given water containing 1% NaCl. Blood pressure was measured weekly. Blood was collected prior to beginning the diets and at the end of completion of the study for analysis of red blood cell (RBC) antioxidant enzymes, RBC and plasma malondialdehyde (MDA), plasma 8-isoprostane and plasma lipids.ResultsCanola oil ingestion significantly decreased the life span of SHRSP rats compared with soybean oil, 85.8 ± 1.1 and 98.3 ± 3.4 days, respectively. Systolic blood pressure increased over time with a significant difference between the diets at the 6th week of feeding. Canola oil ingestion significantly reduced RBC superoxide dismutase, glutathione peroxidase and catalase activities, total cholesterol and low-density lipoprotein cholesterol compared with soybean oil. There were no significant differences in RBC MDA concentration between canola oil fed and soybean oil fed rats. In contrast, plasma MDA and 8-isoprostane concentration was significantly lower in the canola oil group compared to the soybean oil group.ConclusionIn conclusion, canola oil ingestion shortens the life span of SHRSP rats and leads to changes in oxidative status, despite an improvement in the plasma lipids.
Highlights
This study aimed to determine if 25 days of canola oil intake in the absence of excess dietary salt or together with salt loading affects antioxidant and oxidative stress markers in the circulation
Our previous study showed that canola oil intake reduced the antioxidant activities of red blood cell (RBC) superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase compared to soybean oil in SHRSP rats following NaCl loading at the end of their life span [8]
The present study has showed that p22phox and NOX2 mRNA expression was reduced in the canola oil group with the presence of salt, indicating that ·O2ˉ generated from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase may be decreased
Summary
This study aimed to determine if 25 days of canola oil intake in the absence of excess dietary salt or together with salt loading affects antioxidant and oxidative stress markers in the circulation. Our previous study showed that canola oil intake reduced the antioxidant activities of red blood cell (RBC) superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase compared to soybean oil in SHRSP rats following NaCl loading at the end of their life span [8]. Evidence has shown that in canola oil fed spontaneously hypertensive rats (SHR) there was an increase in RBC glutathione and glutathione reductase, with a decrease in the activity of RBC GPx. in the hepatic cytosol, the activity of SOD and catalase were significantly reduced [11]. Similar results were found in a study by Ohara et al [12], in which the activities of catalase, GPx and glutathione reductase were decreased in the liver of canola oil fed WistarKyoto (WKY) rats Taken together these results indicate that canola oil ingestion affects antioxidant enzyme activity in different tissues
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