Horm Metab Res 2014; 46(11): 768-773
DOI: 10.1055/s-0034-1371869
Endocrine Research
© Georg Thieme Verlag KG Stuttgart · New York

Osteocalcin Induces Growth Hormone/Insulin-Like Growth Factor-1 System by Promoting Testosterone Synthesis in Male Mice

Y. Li
1   Department of Orthopedics, Xiangya Hospital, Central-South University, Changsha, Hunan, P. R. China
,
K. Li
1   Department of Orthopedics, Xiangya Hospital, Central-South University, Changsha, Hunan, P. R. China
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Publikationsverlauf

received 28. November 2013

accepted 06. März 2014

Publikationsdatum:
01. April 2014 (online)

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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.