title: Osteocalcin induces growth hormone/insulin-like growth factor-1 system by promoting testosterone synthesis in male mice.
abstract: Osteocalcin has been shown to enhance testosterone production in men. In the present study, we investigated the effects of osteocalcin on testosterone and on induction of the growth hormone/insulin-like growth factor-1 axis. Osteocalcin injection stimulated growth, which could be inhibited by castration. In addition, osteocalcin induced testosterone secretion in testes both in vivo and in vitro. Using real-time polymerase chain reaction and Western blotting, we showed that growth hormone expression was significantly increased in the pituitary after osteocalcin injection (p<0.05). Growth hormone expression in CLU401 mouse pituitary cells was also significantly stimulated (p<0.05) by osteocalcin-induced MA-10 cells. Osteocalcin injection also promoted hepatic expression of growth hormone receptor and insulin-like growth factor-1 (p<0.05), as demonstrated by real-time polymerase chain reaction and Western blotting. Similarly, osteocalcin-induced MA-10 cells promoted growth hormone receptor and insulin-like growth factor-1 expression in NCTC1469 cells. These results suggest that the growth-stimulating activities of osteocalcin are mediated by testicular testosterone secretion, and thus provide valuable information regarding the regulatory effects of osteocalcin expression on the growth hormone/insulin-like growth factor-1 axis via reproductive activities.
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central-South University, Changsha, Hunan, P. R. China.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central-South University, Changsha, Hunan, P. R. China.
authors.forename: K
authors.initials: K
authors.lastname: Li
mesh_terms: D000818:Animals; D002460:Cell Line; D013006:Growth Hormone / Q000378:metabolism*; D048788:Growth and Development / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D015675:Osteocalcin / Q000008:administration & dosage / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011986:Receptors, Somatotropin / Q000378:metabolism; D013737:Testis / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000096:biosynthesis* / Q000097:blood
chemical_list: D011986:Receptors, Somatotropin; D015675:Osteocalcin; D013739:Testosterone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone