Quercetin as a nephroprotector after warm ischemia: histomorphometric evaluation in a rodent model

Purpose:

To quantitatively evaluate the possible long-term protective effects of quercetin during renal warm ischemia.

Materials and Methods:

Male rats were allocated into 4 groups: sham (S), sham quercetin (SQ), ischemia (I), and ischemia quercetin (IQ). Groups SQ and IQ received quercetin (50mg/kg) before and after surgery. Groups I and IQ had their left renal vessels clamped for 60 minutes. All animals were euthanized four weeks after the procedure, and serum urea and creatinine levels were measured. Renal weight and volume, cortex-non-cortex area ratio (C-NC), cortical volume (CV), glomerular volumetric density (Vv[glom]), volume-weighted glomerular volume (VWGV) and number of glomeruli per kidney (N[glom]) were evaluated by stereological methods. Results were considered statistically significant when p <0.05.

Results:

Serum urea levels in group I increased by 10.4% in relation to group S, but no differences were observed among the other groups. The C-NC of group I was lower than those of all other groups, and group IQ had similar results to sham groups. The Vv[glom] and N[glom] of group I were lower than those of group S (33.7% and 28.3%, respectively) and group IQ had no significant difference compared to the S group.

Conclusions:

Quercetin was effective as a nephroprotective agent in preventing the glomerular loss observed when the kidney was subjected to warm ischemia. This suggests that this flavonoid may be used preventively in kidney surgery, when warm ischemia is necessary, such as partial nephrectomy.

Histomorphometric and biochemical data of rat kidney submitted to warm ischemia associated with resveratrol treatment

The data presented here come from the article "Histomorphometric evaluation of the rat kidney submitted to warm ischemia and the protective effect of resveratrol" [1]. Rats of Wistar lineage (n = 39; 9 weeks of age) were obtained and apportioned into 4 groups at random. Both groups Sham (S) and Sham Resveratrol (SR) were submitted to open laparotomy and dissection of the left renal pedicle, the same as groups Ischemia (I) and Ischemia Resveratrol (IR), being the last two also submitted to 1 h left warm renal ischemia. SR and IR were treated with 30 mg/kg of resveratrol intraperitoneally 1 h before the surgical procedure, while S and I received saline injections. Rats were killed a month after surgery by anesthetic overdose. A blood sample was collected by cardiac puncture for determination of serum urea and creatinine serum by biochemical analysis at automated enzymatic method. Kidneys were weighted, Sherle´s method was used for measurement of their volume and then both were fixated in buffered formalin for 48 h. Cortex-non-cortex areas ratio (C-NC) was assessed by Cavalieri's method using a stereoscope. The product of multiplying the renal volume by the C-NC is the cortical volume (CV). Left kidneys fragments were processed for histology resulting in slides that were stained with haematoxylin and eosin. For histomorphometric analyses, 25 random cortical fields were photographed at 200x magnification using a camera attached to a light microscope. The estimation of glomerular volumetric density (Vv [Glom]), indication of proportional volume occupied by glomeruli in the cortex, was performed by the point-counting method. The point-sampled intercepts method was used to estimate the volume-weighted mean glomerular volume (VWGV). Total number of glomeruli per kidney (N [Glom]) estimation was achieved through the formula CVxVv [Glom]/VWGV. All the data were tabulated in spreadsheets. The quantitative results were compared by one-way ANOVA with Tukey's post-test using GraphPad Prism software. All results were considered significant when the value of p <0.05.

Histomorphometric evaluation of the rat kidney submitted to warm ischemia and the protective effect of resveratrol

BACKGROUND

The objective of this study is to quantitatively evaluate the protective effects of resveratrol for using during renal warm ischemia.

METHODS

Rats were allocated into 4 groups: Sham, Sham Resveratrol, Ischemia, Ischemia Resveratrol. Sham Resveratrol and Ischemia Resveratrol received resveratrol before surgery. Ischemia and Ischemia Resveratrol had renal vessels clamped. Animals were euthanized four weeks after. Serum urea and creatinine were measured. Renal weight and volume, cortex-non-cortex areas ratio, cortical volume, glomerular volumetric density, volume-weighted mean glomerular volume and number of glomeruli per kidney were evaluated.

RESULTS

Serum urea in Ischemia increased by 10.4% compared to Sham and no differences were observed among Ischemia Resveratrol and sham groups. The glomerular volumetric density and number of glomeruli of Ischemia were lower than Sham but Ischemia Resveratrol had no difference compared to sham groups.

CONCLUSIONS

Preoperative administration of resveratrol has renoprotective effects, preventing the glomerular number reduction observed in warm ischemia.