Effects of high fat diet on kidney lipid content and the Na,K-ATPase activity

Abstract

It is widely known that high fat diet (HFD) can contribute to the advent of health problems. Recent studies have indicated that obesity imposes a hemodynamic overload to the kidneys. In order to further investigate such injuries, two groups of six Swiss mice each were fed with a controlled AIN93G diet or a high fat (AIN93G modified) diet for eight weeks. Blood samples were collected to determine the hormonal, lipid profile, glucose, urea, and creatinine levels. Histopathological and immunohistochemical analysis were carried out to analysis the kidney damage. Fractions of renal membranes were prepared to assess the Na,K-ATPase activity, lipid peroxidation, total cholesterol, and phospholipid content. The results indicated that the blood lipid profile, urea and creatinine was not altered by the HFD. On the other hand, it was observed in HFD diet mice elevated glucose blood levels along with an augment on insulin and a decrease on corticosterone release. HFD provoked a reduction in the diameter of the convoluted tubules and cell volume in Bowman's capsule and an increased number of positive cells with Na,K-ATPase, but reduced the Na,K-ATPase activity and the cholesterol content in the kidney cell membrane but favored the lipid peroxidation.

Evaluation of the effect of cafeteria diet on the kidney Na,K‐ATPase activity, and oxidative stress

“…We previously evaluated Na,K‐ATPase activity in the right and left kidney of Swiss male rats submitted to an HFD for 8 weeks, with a significant decrease in enzyme activity in both the right and left kidney in the group treated with high‐fat diet in relation to the control group, which received a standard diet. Thus, this decrease may be related to an increase of insulin causing internalization of Na,K‐ATPase …”

“…We also observed lower total cholesterol content in the right and left kidney membranes of rats submitted to HFD in relation to the standard diet group. ROS, as a result of the ingestion of HFD, modifies the cell membrane lipid content and may be a factor for the reduction of cholesterol content in the membrane …”

“…Thus, this decrease may be related to an increase of insulin causing internalization of Na,K-ATPase. 16 According to Kennedy et al, 36 there is a correlation between HFD and Na,K-ATPase activity due to the interaction between the enzyme, which undergoes endocytosis in hyperlipidemic states, and CD36, a key receptor in the metabolism of glucose and fatty acids. The study reports that products generated in hyperlipidemic states are able to activate CD36 and Na,K-ATPase, leading to the production of ROS, proposing that both act synergistically, potentiating an inflammatory cycle in the cells of the proximal renal tubule.…”

“…In an earlier work by our group, we observed that weight gain is prompted by a diet rich in lipids, with renal cellular morphology alterations and no effects on the blood levels of creatinine and urea. Na,K‐ATPase, an important enzyme for renal function, increases its expression in mouse kidneys and decreases its activity upon HFD . However, it is still unclear whether it is the high lipids in the diet or the increase in calories that leads to the modulation observed.…”

“…Na,K-ATPase, an important enzyme for renal function, increases its expression in mouse kidneys and decreases its activity upon HFD. 16 However, it is still unclear whether it is the high lipids in the diet or the increase in calories that leads to the modulation observed.…”