NPY and osteoporosis: TRAP is a classic marker of osteoclasts that enhances bone resorption activity (49); Npy, a multifunctional neuropeptide, not only promotes adipogenesis and inhibits osteogenic differentiation of mesenchymal stem cells but is also upregulated during aging and osteoporosis, while Npy deficiency in bone cells is associated with a high bone mass phenotype (50, 51); Clc-7 is a critical chloride channel located in the ruffled border of osteoclasts, essential for bone resorption (52).