Steroid hormone production via the adrenal cortex, gonads, and placenta (so-called
glandular steroidogenesis) is responsible for the endocrine control of the body’s
homeostasis and is organized by a feedback regulatory mechanism based on the hypothalamus–pituitary–steroidogenic
gland axis. On the other hand, recently discovered extraglandular steroidogenesis
occurring locally in different tissues is instead linked to paracrine or autocrine
signaling, and it is independent of the control by the hypothalamus and pituitary
glands. Bone cells, such as bone-forming osteoblasts, osteoblast-derived osteocytes,
and bone-resorbing osteoclasts, respond to steroid hormones produced by both glandular
and extraglandular steroidogenesis. Recently, new techniques to identify steroid hormones,
as well as synthetic steroids and steroidogenesis inhibitors, have been introduced,
which greatly empowered steroid hormone research. Based on recent literature and new
advances in the field, here we review the local role of steroid hormones in regulating
bone homeostasis and skeletal lesion formation. The novel idea of extraglandular steroidogenesis
occurring within the skeletal system raises the possibility of the development of
new therapies for the treatment of bone diseases.
