Cadmium (Cd) is a heavy metal with public health importance because it is known to present environmental and occupational hazards and a threatening to public health. Cd has negative effects on the liver, kidney, and male fertility. However, relatively little is known about the molecular toxicology of Cd in the epithelial cells of the male reproductive system. Thus, we studied the effects of Cd on the critical metal binging protein, metallothionein-1 (MT-1), in the epididymis of the intact rat. CdCl2 (2 mg/kg/day) was administered for 10 days via minisomotic pumps implanted subcutaneously in mature male rats, and the rats were then sacrificed and their tissues , including the kidney and epididymis, were quickly frozen and examined via immunohistochemistry for MT-1, vacuolar H+ - ATPase (V-ATPase) at confocal microscopic level or MT-1 (Western blot). We observed a significant upregulation of MT-1 expression in kidney proximal tubules by immunofluorescence and Western blot. MT-1 was positive over most of the basal cells (BC) along the epididymal duct and part of the clear cells (CC) in the caudal duct that co-localized with V-ATPase, a CCs marker. MT-1 expression was upregulated in distal caudal CCs after Cd treatment. However, the overall MT-1 expression assayed by Western blot in the epididymal duct decreased after treatment. This study indicated the validity of Cd administration via subcutaneous minipump. MT-1 was upregulated in caudal CCs after Cd treatment. The MT-1 change deserves further investigation
