Short-Term Diet Restriction but Not Alternate Day Fasting Prevents Cisplatin-Induced Nephrotoxicity in Mice

Beneficial effects of time and energy restriction diets on the development of experimental acute kidney injury in Rat: Bax/Bcl-2 and histopathological evaluation

People's lifestyles and, especially, their eating habits affect their health and the functioning of the organs in their bodies, including the kidneys. One's diet influences the cells' responses to stressful conditions such as acute kidney injury (AKI). This study aims to determine the preconditioning effects of four different diets: energy restriction (ER) diet, time restriction (TR) eating, intermittent fasting (IF), and high-fat diet (HF) on histopathological indices of the kidney as well as the molecules involved in apoptosis during AKI. Adult male rats underwent ER, TR, IF, and HF diets for eight weeks. Then, AKI was induced, and renal function indices, histopathological indices, and molecules involved in apoptosis were measured. In animals with AKI, urinary albumin excretion, serum urea, creatinine and, Bax/Bcl-2 ratio increased in the kidney, while renal eGFR decreased. ER and TR diets improved renal parameters and prevented an increase in the Bax/Bcl-2 ratio. The IF diet improved renal parameters but had no effect on the Bax/Bcl-2 ratio. On the other hand, the HF diet worsened renal function and increased the Bax/Bcl-2 ratio. Histopathological examination also showed improved kidney conditions in the ER and TR groups and more damage in the HF group. This study demonstrated that ER and TR diets have renoprotective effects on AKI and possibly cause the resistance of kidney cells to damage by reducing the Bax/Bcl-2 ratio and improving apoptotic conditions.

Short-term control of diet affects cisplatin-induced acute kidney injury through modulation of mitochondrial dynamics and mitochondrial GSH

Obesity affects acute kidney injury (AKI) induced by various clinical settings, including transplantation and cisplatin-cancer therapy. However, the effect of short-term food intake change remains to be defined. Here, we investigated the effects of short-term high-fat diet intake and food restriction on cisplatin-induced AKI. Mice were fed either a high-fat diet (HFD) or a low-fat diet (LFD) for 11 days or were not fed for 40 hh (fasting), before cisplatin administration. Cisplatin-induced functional and structural damages to kidneys in both HFD- and LFD-fed mice, with greater damages in HFD-fed mice than LFD-fed mice. HFD decreased mitochondrial total glutathione (tGSH) level, along with increases in the plasma and kidney cholesterol levels. Cisplatin caused the increase of kidney cholesterol levels and oxidative stress, along with the decrease of mitochondrial tGSH levels. In addition, cisplatin-induced mitochondrial damage and apoptosis of tubular cells in both HFD- and LFD-fed mice. An increase of Fis1 (mitochondria fission 1 protein), whereas a decrease of Opa1 (mitochondria fusion 1 protein) occurred by cisplatin. These cisplatin effects were greater in HFD-fed mice than in LFD-fed mice. Administration of mitochondria-specific antioxidant treatment during HFD feeding inhibited these cisplatin-induced changes. Fasting for 40 h also significantly reduced the cisplatin-induced changes mentioned above. These data demonstrate that short-term HFD intake worsens cisplatin-induced oxidative stress by the reduction of mitochondrial tGSH, resulting in increased cisplatin-induced nephrotoxicity. These data newly indicate that the control of calorie intake, even for a short period, affects kidney susceptibility to injury. Although most studies described the effects of a long-term high-fat diet on the kidneys, in this study, we found that even if a high-fat diet was consumed for a short-term, physiological changes and mitochondria tGSH decrease in the kidneys, and consequently increased cisplatin-nephrotoxic susceptibility. These data suggest the association of calorie intake with kidney susceptibility to cisplatin.

Effects of caloric and time restriction diets on kidney health in rat model of postmenopausal acute kidney injury: An apoptosis and histopathological study

Objectives

Lifestyle and eating habits affect the health and function of the body's organs, including the kidneys. The current study was carried out to determine the effects of two types of diet programs, including time restriction (TR) and calorie restriction (CR) on the histopathological changes and apoptotic molecules during acute kidney injury (AKI) in postmenopausal rats.

Materials and Methods

In this study the female rats were divided into two groups of ovariectomized (OVX) and ovary-intact (sham), then they were placed on TR and CR diets for 8 weeks; afterward, AKI was induced by injection of glycerol. Functional indices, histopathological changes, Bax, and Bcl2 were measured before and after AKI.

Results

After AKI, creatinine, serum urea, urinary albumin excretion, kidney tissue Bax, and Bax/Bcl2 ratio increased, while glomerular filtration rate (GFR) and kidney tissue Bcl2 decreased compared with before AKI. Histopathological indices (inflammation, cellular necrosis, cell vacuolization, tubular dilatation, intratubular cast, and congestion) also confirmed renal injury. TR and CR diets improved renal injury indices and prevented an increase in the Bax/Bcl2 ratio. However, in some indices, the effects of two diets on OVX animals were not observed. In addition, none of the diets could decrease kidney weight/body weight ratio (KW/BW). The histopathological finding also showed improvement of renal status in both groups, especially in the CR diet.

Conclusion

The results indicated that TR and CR diets had renoprotective effects against AKI by reducing the Bax/Bcl2 ratio and improving apoptosis. The effects of CR were more than TR.

Dietary Restriction for Kidney Protection: Decline in Nephroprotective Mechanisms During Aging

Dietary restriction (DR) is believed to be one of the most promising approaches to extend life span of different animal species and to delay deleterious age-related physiological alterations and diseases. Among others, DR was shown to ameliorate acute kidney injury (AKI) and chronic kidney disease (CKD). However, to date, a comprehensive analysis of the mechanisms of the protective effect of DR specifically in kidney pathologies has not been carried out. The protective properties of DR are mediated by a range of signaling pathways associated with adaptation to reduced nutrient intake. The adaptation is accompanied by a number of metabolic changes, such as autophagy activation, metabolic shifts toward lipid utilization and ketone bodies production, improvement of mitochondria functioning, and decreased oxidative stress. However, some studies indicated that with age, the gain of DR-mediated positive remodeling gradually decreases. This may be an obstacle if we seek to translate the DR approach into a clinic for the treatment of kidney diseases as most patients with AKI and CKD are elderly. It is well known that aging is accompanied by impairments in a huge variety of organs and systems, such as hormonal regulation, stress sensing, autophagy and proteasomal activity, gene expression, and epigenome profile, increased damage to macromolecules and organelles including mitochondria. All these age-associated changes might be the reasons for the reduced protective potential of the DR during aging. We summarized the available mechanisms of DR-mediated nephroprotection and described ways to improve the effectiveness of this approach for an aged kidney.

Nutritional Preconditioning in Cancer Treatment in Relation to DNA Damage and Aging

Dietary restriction (DR) is the most successful nutritional intervention for extending lifespan and preserving health in numerous species. Reducing food intake triggers a protective response that shifts energy resources from growth to maintenance and resilience mechanisms. This so-called survival response has been shown to particularly increase life- and health span and decrease DNA damage in DNA repair-deficient mice exhibiting accelerated aging. Accumulation of DNA damage is the main cause of aging, but also of cancer. Moreover, radiotherapies and most chemotherapies are based on damaging DNA, consistent with their ability to induce toxicity and accelerate aging. Since fasting and DR decrease DNA damage and its effects, nutritional preconditioning holds promise for improving (cancer) therapy and preventing short- and long-term side effects of anticancer treatments. This review provides an overview of the link between aging and cancer, highlights important preclinical studies applying such nutritional preconditioning, and summarizes the first clinical trials implementing nutritional preconditioning in cancer treatment.