Changes in Serum and Tissue Zinc Levels in Sex Hormone-Induced Prostatic Carcinogenesis in the Noble Rat

Abstract

We investigated the changes in serum and tissue zinc levels in the Noble rat prostate gland under different pathological conditions induced by the administration of a combination of testosterone and 17β-estradiol. The results showed that there were significant differences in serum zinc values between normal and hormone-treated rats with prostatic hyperplasia, dysplasia and prostatic carcinoma (p < 0.05), although there was no significant difference among rats with different forms of prostatic lesions (i.e. hyperplasia, dysplasia and prostatic adenocarcinoma). There was also a difference in zinc content between the lateral prostate (LP), ventral prostate (VP) and dorsal prostate (DP) in normal rats. The zinc levels of LP were several times greater than those of either VP or DP (p < 0.01). There was also a great difference in zinc levels between the normal and the hyperplastic/dysplastic and carcinomatous LP and VP (p < 0.05). The levels of zinc in both LP and VP were increased in hyperplasia/dysplasia and carcinoma. On the other hand, the zinc levels of LP were much higher than those of VP in hyperplasia/dysplasia and carcinoma (p < 0.01), which may be correlated with the incidence of prostate cancers in these lobes (i.e. higher in LP and much lower in VP). In contrast, in DP, the levels of zinc were not affected, which may be correlated with the very low incidence of carcinoma in this lobe. Our data suggest that the difference in zinc levels among these lobes reflect the heterogeneity in zinc content in various lobes of the rat prostate. The growth and development of prostatic lesions in LP and VP may be positively correlated with the significant increase in tissue zinc levels in these lobes. On the other hand, the lack of response of DP to carcinogenesis may be due to its relatively stable low zinc levels. It is suggested that tissue zinc content may be used as a marker for prostatic lesions, including hyperplasia, dysplasia and carcinoma, while serum zinc levels may be a useful indicator for abnormal prostatic growth.