The effect of calcium status on the immune function of ovariectomized rats

Abstract

Mineral supplements are helpful for strong bones and the immune system plays an important role in postmenopausal stimulation of bone loss. This study examined the effect of calcium‐deficiency diet on immune functions and cell viability in ovariectomized rats (OVX). The treatments were as follows: Group 1, sham/AIN‐93M diet(0.5% Ca diet); Group 2, low‐Ca diet (0.25% Ca);Group 3, OVX/AIN‐93M diet; and Group 4, OVX/low‐Ca diet (0.25% Ca). The treated rats were sacrificed after 10 wks. In vitro lymphocyte proliferative responses and NK cell activity were measured in pooled spleen from each group. The mitogenic activity of lymphocytes in the spleen was slightly reduced in low‐Ca diet group. Ovariectomy caused a little decrease in the tumoricidal activity of NK cells, whereas low‐Ca diet resulted in the increase of tumoricidal acitivity. Ovariectomy caused the decrease of reactive oxygen species and NO production by macrophages. In contrast, low‐Ca diet induced the increase of tumoricidal activity. Moreover, ovariectormy marginally increased cell viability, whereas cell viability was reduced in group receiving low‐dose Ca supplement. Cell death was more pronounced in OVX on low Ca diet. Overall, our data suggest that calcium status of the animal has a differential effect on the function of immune cells. (This work was supported by grant No. RTI05‐01‐02 from the Regional Technology Innovation Program of MOCIE)