Abstract
Previous studies showed an increased prevalence of cataracts in postmenopausal women. In this study, we investigated changes in the levels of calcium ion (Ca2+) and interleukin (IL)-18, which are factors in cataract development, in the lenses of ovariectomized (OVX) rats, a model of postmenopausal woman. Although the Ca2+ content in the blood of OVX rats increased 1 month after ovariectomy and subsequently decreased, the Ca2+ content in the lenses was unchanged in OVX rats 1–3 months after ovariectomy. The Ca2+-ATPase activity in the lenses of OVX rats peaked 1 month after ovariectomy, and the behavior of Ca2+-ATPase activity in lenses of OVX rats was similar to that of the Ca2+ concentration in the blood. It is possible that hypercalcemia increases the Ca2+ inflow into the lens; however, the enhanced Ca2+-ATPase activity prevents the Ca2+ 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.
