Involvement of renal gamma-glutamyltranspeptidase in differences in the renal uptake of mercuric mercury by male and female mice of various strains and ages

Involvement of renal gamma-glutamyltranspeptidase (gamma-GTP) in difference s in the renal uptake of Hg2+ by male and female mice of various ages was e xamined using five strains of mice, namely, BALB/cA, C57BL/6N, CBA/JN, C3H/ HeN and ICR. We observed strain-related and gender-related differences in t he renal accumulation of Hg2+ 30 min after the administration of mercuric c hloride (1 mu mol/kg, s.c.). Renal gamma-GTP activity also varied among the tested strains, and the activity in males was about twice that in females, A significant correlation was recognized between renal gamma-GTP activity and the renal accumulation of Hg2+. Both renal uptake of Hg2+ and renal gam ma-GTP activity increased gradually with age in male ICR mice from 2 to 8 w eeks after birth but remained relatively constant in ICR females. Significa nt gender-related differences in both renal accumulation of Hg2+ and gamma- GTP activity were observed 4 weeks after birth and thereafter. Castration o f male ICR mice decreased both renal accumulation of Hg2+ and gamma-GTP act ivity to the levels in females, Injection of testosterone increased both re nal accumulation of Hg2+ and gamma-GTP activity in castrated male mice and in normal female mice to the levels in control male mice. These results sug gest that strain-related, gender-related and age-related differences in the renal accumulation of Hg2+ in mice might be due to differences in renal ga mma-GTP activity and, furthermore, that renal gamma-GTP activity might be c ontrolled, at least to some extent, by testosterone.