INTERMITTENT FASTING MODULATES KIDNEY FUNCTION IN FEMALE RATS

Dietary restrictions have been gaining interest among large populations worldwide. In particular, some reports have shown the beneficial effects of intermittent fasting (IF) protocols on different neurological and cardiovascular diseases. However, the effects on the kidneys are still poorly understood. We aimed to verify the potential impact of IF on renal function. Female Wistar rats (8-10 weeks old) were randomly divided into two experimental groups: 1) CONT (control group, n=4) – with free access to chow; and 2) IF (intermittent fasting group, n=5) - rats subjected to the IF protocol [fasting: 18h (from “zeitgeber time” (ZT)=8 up to ZT=24)/ feeding: 6h (from ZT=1 up to ZT=7)] for 4 weeks. During the feeding period, the rats had free access to chow (CEUA-UFMG#13-2023). Once a week, the rats were housed in metabolic cages (during the feeding period) to measure chow and water intakes, as well as to collect urine for biochemical analysis. Compared to the CONT group, the IF group showed a reduction in body weight (BW, 15%), which was observed despite an increase in water intake (3.0-fold) and food intake (6.0-fold). The IF group also presented a reduction in urinary volume (64%, mL/6h/kg BW) after 2 weeks of diet restriction. No significant alterations were observed in urinary creatinine concentrations. Interestingly, urinary glucose mass was reduced (44%) in the IF group. However, proteinuria and UPCr (the ratio between urinary proteins and creatinine) were increased (1.8-fold and 1.6-fold, respectively). A positive Pearson correlation was found between BW and glycosuria (r=0.4906/R²=0.2407/P=0.001), while an inverse Pearson correlation was found between BW and proteinuria (r=-0.7169/R²=0.5140/P<0.0001). Our preliminary findings suggest that the 4-week IF protocol modulates renal function, especially the mechanisms involved in renal proteins and glucose handling.