Early renal parenchymal histological changes in an experimental model of vesico-ureteral reflux and the role of apoptosis.

OBJECTIVES

To observe early renal parenchymal cellular changes in an experimental model of vesico-ureteral reflux (VUR) and to show whether the apoptotic pathway plays a role in these cellular changes.

MATERIAL AND

METHODS

Fourteen New Zealand breed rabbits were used and were divided into two equal groups (control and experimental groups). Urine samples were obtained in a sterile manner and cultured. In the study group, reflux was created in the right kidneys surgically. Renal scintigraphy and voiding cystourethrography (VCUG) were performed in both groups on Day 17. The kidneys were examined in terms of histology, apoptotic activity and caspase activity.

RESULTS

No growth was observed in urine cultures in either group. VUR was manifested in only two rabbits in the experimental group on VCUG. On renal scintigraphy, no renal scarring was observed in either of the groups and renal uptake values were in the normal range. There was a greater increase in collagen in the right kidneys in the experimental group than in the control group and apoptotic activity was significantly increased in the study group: 0% in the control group, 10.8%+/-0.7% in the experimental group (p<0.001). Caspase-6 activity was strongly positive and caspase-8 and -9 activities were moderately positive in the right kidneys of the experimental group. Caspase-6 activity was moderately positive, and caspase-8 and -9 activities were weakly positive in the contralateral kidneys of the experimental group. Caspase activities in the control group were negative (p<0.001).

CONCLUSIONS

In this experimental model of VUR, apoptotic activity was initiated via the caspase-8 and -9 pathway and collagen tissue increased in the renal parenchyma where reflux occurred. The balance of apoptotic activity may play a key role in the occurrence of reflux nephropathy.