The effect of the partial obstruction site of the renal vein on testis and kidney in rats: is the traditional animal model suitable for varicocele research?

Abstract

Purpose: We investigated the influence of the location of the partial renal vein obstruction on the left kidney, the bilateral testes, and cauda epididymal sperm quality and determined whether this animal model is suitable for varicocele study.

Materials and methods: A total of 25 adult male Sprague-Dawley rats were assigned to three groups: group 1 (experimental varicocele by partial ligation medial to the internal spermatic vein for 8 weeks, n=8), group 2 (partial ligation lateral to the internal spermatic vein for 8 weeks, n=10), and group 3 (sham operation for 8 weeks, n=7). Rats in groups 1, 2, and 3 underwent a left nephrectomy and bilateral orchiectomy at 8 weeks after the operation. Histological changes and Johnsen score in both testes were analyzed. Fibrotic changes in the left kidney were assessed by quantitative image analysis. Numbers of sperm and proportions of motile sperm in the cauda epididymides were determined.

Results: Significant histological abnormalities and Johnsen score changes were observed in the testes in group 1. Renal fibrosis did not differ significantly among the groups. The proportions of motile sperm were significantly lower bilaterally in group 1 than in groups 2 and 3. However, the mean bilateral epididymal sperm count in group 1 was not significantly lower than in groups 2 and 3.

Conclusions: Our results showed that experimental varicocele in the rat, induced by partial ligation medial to the internal spermatic vein, influences epididymal sperm quality without harmful effects on the left kidney. The present study certifies that this traditional animal model is suitable for varicocele research.

Keywords: Animal models; Physiopathology; Rats; Varicocele.

FIG. 1

Schematic illustration showing the different site of partial ligation of the left renal vein. (A) Group 1, partial ligation medial to the internal spermatic vein (B) Group 2, partial ligation lateral to the internal spermatic vein.

FIG. 2

Dilatation of the internal spermatic vein after partial ligation of the left renal vein medial to the internal spermatic vein insertion site (arrow).

FIG. 3

H&E stain of the left testis (×20 objective). (A) Group 1: Histological changes such as reduced spermatogenesis, germ cell desquamation, and increased congestion are observed. (B) Group 2: normal seminiferous tubules and interstitial spaces are observed. (C) Group 3: normal seminiferous tubules and interstitial spaces are observed.

FIG. 4

Masson's trichrome stain of the left kidney (×10 objective). (A) Group 1, (B) Group 2, (C) Group 3. The structures of the glomerulus and of the proximal and distal tubules were well preserved regardless of the operation type.