Cadmium accumulation and metallothionein overexpression in internal spermatic vein of patients with varicocele.

To determine the possible molecular mechanism for the thickened wall in the internal spermatic vein (ISV) of patients with varicocele, we examined the cadmium (Cd) content and metallothionein (MT) expression in these diseased vessels. Previous studies have shown that Cd might play a role in the etiology of varicocele-associated infertility. MT, a metal-binding protein, protects against cell apoptosis during hypoxia. The study group consisted of 20 patients with grade 3 left varicocele. The control group consisted of 15 volunteers with left-sided indirect inguinal hernia. Through a left inguinal incision, a 1-cm section of the ISV was resected from each patient to measure the Cd and MT levels. The results were analyzed using Student's t test. The Cd content in the ISV was 59.84 +/- 5.7 ng/g in the control group and 192.1 +/- 24.2 ng/g in the varicocele group. The relative intensity of the MT band was 40.52 +/- 3.74 in the control group and 78.26 +/- 5.61 in the varicocele group. MT expression was greater in the varicocele group than in the control group, and its deposition in the vascular endothelial layer was predominant using immunohistochemistry staining and confocal laser scanning. The results of the present study have demonstrated a greater accumulation of Cd in the ISV of the varicocele group than in the control group. The high Cd content and hypoxic conditions would induce overexpression of MT in the diseased vessels to protect the vascular cells from apoptosis. This might be a mechanism for the thickened wall of the ISV in patients with varicocele.