Meeting Abstract

P1.89  Tuesday, Jan. 4  LOCOMOTOR STRESS AND MINERAL MOBILIZATION FROM THE MATERNAL SKELETON HOOD, Wendy R; Auburn University wrhood@auburn.edu

During reproduction, female mammals support the ossification of their offspring’s skeletons by supplementing dietary mineral with mineral mobilized from their own bone. The relative contribution of mothers likely rises with litter size, so constraints on the availability of minerals such as calcium may impact offspring development. The skeletal system alters rates of bone deposition in response to relative change in mechanical stress. Thus, I predicted that high locomotor stress, as expected for wild mice, would counter loss of bone mineral and ultimately reduce mineral transferred to offspring. I compared bone mineralization parameters between mice in cages that require the following degrees of skeletal stress and energy expenditure (EE) associated with acquiring food: A) high stress, high EE associated with climbing a 60 cm tower, B) low stress, high EE associated with running a 100 cm tunnel and C) low stress, low EE associated with living a standard mouse box. I found no difference between groups in the mineral content of mother’s femur at peak lactation. However, the femurs of females in the climbing group did display a change in bone architecture with climbing females displaying an increase in trabecular bone density and number of trabeculae and a decrease in cortical bone surface area. Thus, the results of this investigation suggest that high stress locomotion does not overcome the stimulation to mobilize bone to support offspring development. Instead, locomotor stress may improve the strength of maternal bone associated with an increase in number of osseous struts that help the bone to withstand mechanical stress.