ADRB2 and mucopolysaccharidosis: Although hyperactivation of sympathetic tone stimulates bone resorption and bone loss via Adrb2 signaling in osteoblasts, clinical findings of blockade of β-adrenergic receptors to prevent bone destruction are still contradictory.70–72 Intriguingly, RU486 treatment rescued the significantly decreased NE levels in the serum and femoral head to a relative normal level in MPS-treated-mice, which facilitated the skeleton and endothelial homeostasis in femoral head.