腎主骨 骨生髓

腎藏精，主生長、發育、生殖，主納氣、水液，主骨生髓，通於腦，其華在髮，開竅於耳及二陰。腎臟虧損，精少而天癸竭，是衰老的根本。臨床可見精神不振、頭暈、手足不溫、內分泌減少、性慾漸消、月經減退、耳鳴耳聾、夜尿、小便不暢等。老人筋骨萎縮，故可見體態鬆垮、牙齒鬆脫、腰膝萎軟、背彎傴僂，步履不穩，關節失靈，行動艱難。腎虛鬚髮失榮，則變脆變灰，稀疏，甚至脫光。

 

Endocrine Regulation of Male Fertility by the Skeleton

Franck Oury, Grzegorz Sumara, Olga Sumara, Mathieu Ferron, Haixin Chang, Charles E. Smith, Louis Hermo, Susan Suarez, Bryan L. Roth, Patricia Ducy, Gerard Karsenty

Cell, Volume 144, Issue 5, p796–809, 4 March 2011

Highlights
Bone regulates male fertility
Osteoblast-derived osteocalcin enhances testosterone production by Leydig cells
Osteocalcin signals through a G protein-coupled receptor, Gprc6a, in Leydig cells

Summary
Interactions between bone and the reproductive system have until now been thought to be limited to the regulation of bone remodeling by the gonads. We now show that, in males, bone acts as a regulator of fertility. Using coculture assays, we demonstrate that osteoblasts are able to induce testosterone production by the testes, though they fail to influence estrogen production by the ovaries. Analyses of cell-specific loss- and gain-of-function models reveal that the osteoblast-derived hormone osteocalcin performs this endocrine function. By binding to a G protein-coupled receptor expressed in the Leydig cells of the testes, osteocalcin regulates in a CREB-dependent manner the expression of enzymes that is required for testosterone synthesis, promoting germ cell survival. This study expands the physiological repertoire of osteocalcin and provides the first evidence that the skeleton is an endocrine regulator of reproduction.