Dietary strontium increases bone mineral density in intact zebrafish (Danio rerio): A potential model system for bone research

Zebrafish (Danio rerio) skeletal bone possesses properties similar to human bone, which suggests that they may be used as a model to study mineralization characteristics of the human Haversian system, as well as human bone diseases. One prerequisite for the use of zebrafish as an alternative osteoporotic bone model is to determine whether their bone displays functional plasticity similar to that observed in other bone models. Strontium citrate was supplemented into a laboratory-prepared diet (45% crude protein) to produce dietary strontium levels of 0%, 0.63%, 1.26%, 1.89%, and 2.43% and fed ad libitum twice daily for 12 weeks to 28-day-old intact zebrafish. Length was determined at 4-week intervals, and both weight and length were recorded at 12 weeks. At 12 weeks, seven zebrafish from each dietary level were analyzed for total bone mineral density by microcomputed tomography. Dietary strontium citrate supplementation significantly (p < 0.05) increased zebrafish whole-body and spinal column bone mineral density. In addition, trace amounts of strontium were incorporated into the scale matrix in those zebrafish that consumed strontium-supplemented diets. These findings suggest that zebrafish bone displays plasticity similar to that reported for other bone models (i.e., rat, mouse, and monkey) that received supplements of strontium compounds and zebrafish should be viewed as an increasingly valuable bone model.