The effect of vitamin A on the course of renal ablation nephropathy.

Abstract

Renal scarring due to pyelonephritis was shown to improve in rats given vitamin A. We evaluated the effect of vitamin A in a renal ablation nephropathy model. Four groups, each including 7 rats with 5/6 nephrectomy, were formed: group I (no vitamin A), group II (60 kIU vitamin A), group III (120 kIU vitamin A), and group IV (180 kIU vitamin A). Four sham-operated rats comprised the control group. After 6 weeks of 5/6 nephrectomy, the rats were sacrificed and serum creatinine, vitamin A, and beta-carotene levels were determined in addition to histopathological evaluation of the remnant kidneys. The tubulointerstitial and glomerular changes were graded as "0-3" and "0-5" respectively, in accordance with the severity of the lesions. Tubulointerstitial score (TIS), mean glomerulosclerosis score (MGS, arithmetical mean of the sclerosis scores of 100 glomeruli), and severity of glomerulosclerosis index (SGI, ratio of the number of glomeruli with grade > or = 3 sclerosis to the total number of glomeruli examined) were calculated for each rat. Serum creatinine levels were higher in the study groups than the control rats (P < 0.05), but there was no significant difference between the study groups (although the levels increased as the dose of vitamin A increased). Serum vitamin A levels were significantly higher in the groups given vitamin A than the control rats and group I (P < 0.05). In addition, serum vitamin A levels increased significantly in parallel to increasing doses of vitamin A (P < 0.05). Serum beta-carotene levels did not differ between the groups, except for group II, which had lower levels than controls (P = 0.01). MGS and SGI were significantly higher in the study groups than control rats (P < 0.05), but did not differ between the study groups. Study and control rats were not different with respect to TIS, but there was a difference between the control group and group III (P = 0.04). Group II had the lowest MGS, SGI, and TIS scores among the study groups. When all the rats were considered together, vitamin A levels did not correlate with the MGS and SGI, but correlated positively with the TIS (r = 0.391, P = 0.027). beta-Carotene levels also did not correlate with the MGS, SGI, and TIS. In conclusion, vitamin A administration did not significantly affect the clinical and pathological course of renal ablation nephropathy in rats. Furthermore, higher doses of vitamin A might even damage renal tissue.