Bone mass is determined by the balance of two opposing activities: bone removal by osteoclasts and bone formation by osteoblasts. Additionally, there are two types of bone tissue: cancellous bone makes up the spongy interior, while cortical bone forms the hard outer portion of the bone.
Estrogens help maintain both types of bone and the estrogen receptor ERα is known to regulate the maintenance of cancellous bone, but ERα's role in the maintenance of cortical bone is unclear. In the Journal of Clinical Investigation, researchers led by Stavros Manalogos at the University of Arkansas for Medical Sciences determined the role of ERα in mouse osteoblasts.
They found that ERα stimulated expansion in the outer, fibrous layer of the bone, known as the periosteum, and prevented removal of the cortical bone. These results demonstrate that ERα plays a context-dependent role in bone formation.
TITLE: Estrogen Receptor-α signaling in osteoblast progenitors stimulates cortical bone accrual