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The effect of ovariectomy and ovarian steroid treatment on growth hormone and insulin‐like growth factor‐I levels in the rat femur
Author(s) -
Suliman Isam A.,
ElBakri Nahid K.,
Adem Abdu,
Mustafa Amged,
Lindgren J Urban
Publication year - 2001
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1016/s0736-0266(01)00058-4
Subject(s) - endocrinology , medicine , ovariectomized rat , insulin like growth factor , estrogen , femur , radioimmunoassay , growth factor , hormone , receptor , surgery
Growth hormone (GH) and insulin‐like growth factor‐I (IGF‐I) are known to play an important role in bone metabolism. The regulation of plasma levels of GH and IGF‐I by ovarian steroids is well known, however, their effect on local GH and IGF‐I is still unclear. In this study, we investigated the effect of ovariectomy and ovarian steroid treatment on the femur GH and IGF‐I levels as well as on bone density in the rat. Nine month‐old rats were ovariectomized (OVX) or sham‐operated (SHAM) and 9 weeks after the surgery they were treated with daily s.c. injections of either 17β‐estradiol (OVX + E), progesterone (OVX + P), or vehicle (OVX + V) for another 10 weeks. GH and IGF‐I levels in the femur extracts were measured by specific radioimmunoassay (RIA). Ovariectomy decreased GH and had no effect on IGF‐I levels. Estradiol treatment increased femur GH and IGF‐I levels compared to SHAM rats. Progesterone restored GH and increased IGF‐I levels. Ovariectomy decreased, estrogen restored and progesterone partially restored femur bone density. Our results demonstrate that ovariectomy and ovarian steroids modulate the levels of GH and IGF‐I in the bone of aged OVX rats. However, these effects appear to be limited to supraphysiological concentrations of estradiol and progesterone. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.