Previous studies showed an increased prevalence of
cataracts in postmenopausal women. In this study, we investigated changes in the levels of
calcium ion (Ca(2+)) and
interleukin (IL)-18, which are factors in
cataract development, in the
lenses of ovariectomized (OVX) rats, a model of postmenopausal woman. Although the Ca(2+) content in the blood of OVX rats increased 1 month after
ovariectomy and subsequently decreased, the Ca(2+) content in the
lenses was unchanged in OVX rats 1-3 months after
ovariectomy. The Ca(2+)-
ATPase activity in the
lenses of OVX rats peaked 1 month after
ovariectomy, and the behavior of Ca(2+)-
ATPase activity in
lenses of OVX rats was similar to that of the Ca(2+) concentration in the blood. It is possible that
hypercalcemia increases the Ca(2+) inflow into the lens; however, the enhanced Ca(2+)-
ATPase activity prevents the Ca(2+) level from rising. On the other hand, we found that the levels of both
IL-18 and
interferon (IFN)-γ in the
lenses of OVX rats were significantly increased as compared with the
lenses of
sham (control) rats during the period 1-3 months after surgery. These results suggest that the expression of IFN-γ via
IL-18 in the
lenses of OVX rats is induced by
ovariectomy, and that excessive
IL-18 and IFN-γ production in the
lenses may be related to
cataract development in postmenopausal women. These findings support those of previous studies that assessed lens opacification in postmenopausal women.