SEMA3A and Osteopenia: Previous studies have suggested that neurons-derived Sema3A is involved in bone development,20 while osteocytes-derived Sema3A is involved in maintaining bone homeostasis in aged mice.21 Another study indicated that deficiency of osteoblast-derived Sema3A led to osteopenia in long bones and lumbar spine.22 We observed increased expression of Sema3A in the trigeminal ganglion during OTM.