Dietary intake of rapeseed oil as the sole fat nutrient in wistar rats - Lack of increase in plasma lipids and renal lesions -

Abstract

INTRODUCTIONLow erucic acid rapeseed (canola) oil (CO) has been reported to shorten survival times in stroke-prone spontaneously hypertensive rats (SHRSP), compared with rats given soybean oil (SO), when each oil was added at 10 w/w% to standard rat chow (Huang et al., , 1997Miyazaki et al., 1998). Previous studies suggested that CO ingestion shortens the life of SHRSP via an acceleration of hypertension-related conditions, including elevation of blood pressure and tissue lesions in the kidney and heart (Naito et al., 2003;Ohara et al., 2006). On the other hand, it was found that CO ingestion elevated blood pressure and plasma lipids and caused vascular lesions not only in SHRSP but in spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats (Naito et al., 2000a(Naito et al., , 2000b. However, such unfavorable effects have been found exclusively in SHRSP and its closely related strains, and there have been no reports on CO-induced effects using rats of other strains. Therefore, the present study examined whether or not such unfavorable effects of CO are restricted to SHRSP and its related strains. For this purpose Wistar rats, the strain from which WKY rats, SHR and SHRSP were derived, were fed a diet containing 10 w/w% CO as the sole fat nutrient for 10 weeks, and the resulting changes in clinical signs were compared with those in control rats fed SO instead of CO. MATERIALS AND METHODS Animals and breedingSixteen male Wistar rats, 4 weeks old, were purchased ABSTRACT -Dietary rapeseed (canola) oil (CO) given as the only fat nutrient shortens life in strokeprone spontaneously hypertensive rats (SHRSP), compared with SHRSP given soybean oil (SO) instead of CO. CO ingestion increases plasma lipids and causes renal lesions in SHRSP and in spontaneously hypertensive rats (SHR), and increases plasma lipids also in Wistar Kyoto (WKY) rats, a normotensive counterpart of SHR. This study examined whether or not such unfavorable effects of CO are restricted to these closely related strains. For this purpose Wistar rats, the strain from which these strains were derived, were fed a diet containing 10% CO or SO as the sole fat nutrient for 10 weeks, and changes in clinical signs, urinalysis, blood biochemistry and pathology were compared. CO ingestion did not induce Na + , compared with the SO group. Thus, the unfavorable effects of CO ingestion appear to be restricted to SHRSP and its closely related strains. The role of increased aldosterone and Na + in the unfavorable events caused by CO in SHRSP, SHR and WKY rats, and any factors which could induce such increases in aldosterone and Na + , remain to be elucidated.

Rapeseed oil-rich diet alters hepatic mitochondrial membrane lipid composition and disrupts bioenergetics

“…In the present work, Wistar-Han rats fed a 20 % rapeseed oil diet for 33 days did not show altered biochemical plasma markers or internal lesions, in agreement with previous studies (Ohara et al 2008). Extra attention was given to the hearts of these animals, which showed increased weight in relation to total animal weight (Table S3).…”

Testosterone-lowering activity of canola and hydrogenated soybean oil in the stroke-prone spontaneously hypertensive rat

“…If such a condition were ubiquitous in organs other than the testis, it is possible that dietary hydrogenated soybean oil and canola oil would cause a relative predomination of mineralocorticoid synthesis over sex hormone synthesis. In this context, it should be noted that in Wistar rats fed a canola oil diet, the serum aldosterone level was significantly higher, by 30%, than in those fed a soybean oil diet (Ohara et al, 2008) and that a similar change was also found in SHRSP given canola oil . Aldosterone plays a crucial role in the cause and exacerbation of vascular injury accompanied with hypertension (Schiffrin, 2006).…”

Rapeseed (canola) oil aggravates metabolic syndrome-like conditions in male but not in female stroke-prone spontaneously hypertensive rats (SHRSP)

“…Previously it was found that the plasma aldosterone level was significantly higher in male Wistar rats fed a CAN diet for 10 weeks than in animals fed a SOY diet [ 50 ]. Moreover, it was also found that testosterone levels in the testis and plasma in SHRSP were significantly decreased after ingestion of a CAN diet for 12 weeks, compared to the control animals given a SOY diet [ 12 ].…”