Objective:To investigate the effects of serotonin of different doses on cortical and trabecular bone parameters of female mice. Methods:Wild-type (wt)C57BL/6 female mice with 2-month-old were injected with serotonin of different doses (0,5,10,20,50 and 100 mg/kg)subcutaneously (s.c.)daily for 3 months. Micro-CT (μCT)was used to quantitatively analyze bone parameters of the fifth lumbar bodies,distal femurs and midshafts of the femurs of each group of mice. Results:Compared to the control groups mice,the 10-100 mg/kg groups had significantly reduced trabecular numbers,trabecular bone volume and surface density,and increased trabecular separation,leading to a decrease of trabecular bone mineral density and bone mineral capacity. Mice in the 50-100 mg/kg groups caused significantly decreased cortical bone mineral capacity secondary to reduced cortical thickness and cortical bone volume density. Conclusion:Serotonin has a significantly negative regulation on bone metabolism in mice.