title: Effects of estrogen replacement on insulin-like growth factor I concentrations in serum and bone tissue and on interleukin 1 secretion from spleen macrophages in oophorectomized rats.
abstract: Oophorectomy (OOX) has been known to increase bone turnover, but its precise mechanism is not fully understood. In order to further investigate the mechanism, we determined insulinlike growth factor I (IGF-I) concentrations in serum and bone tissue and interleukin 1 (IL-1) release from spleen macrophages in oophorectomized rats because it has been demonstrated that IGF-I stimulates bone formation and IL-1 stimulates bone resorption. Female 8-week-old Wistar rats were divided into four groups: (1) control, (2) OOX, (3) OOX given estradiol, and (4) control given estradiol. Ten micrograms/kg of 17 beta-estradiol was given daily by subcutaneous injection. After 5 weeks of treatment, IGF-I concentrations in the extract from right femur and in serum were determined by specific radioimmunoassay. IL-1 activity released from lipopolysaccharide (LPS)-stimulated spleen macrophages was determined by bioassay. IGF-I contents in the femur and IGF-I concentrations in serum in oophorectomized rats were significantly higher than those in control rats. Treatment by estradiol inhibited the increase in IGF-I concentrations both in femur and in serum. IL-1 release from LPS-stimulated spleen macrophages in oophorectomized rats was increased, and treatment by estradiol also inhibited the stimulated IL-1 release. The ash weights and the calcium contents of left femur in oophorectomized rats were lower than those in control rats. These results suggest that both IGF-I and IL-1 may be involved in the mechanism of the regulation of bone turnover in oophorectomized rats.
authors.affiliation: Department of Geriatrics, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Sato
authors.forename: Y
authors.initials: Y
authors.lastname: Ouchi
authors.forename: A
authors.initials: A
authors.lastname: Masuyama
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Hosoi
authors.forename: Y
authors.initials: Y
authors.lastname: Okamoto
authors.forename: N
authors.initials: N
authors.lastname: Sasaki
authors.forename: M
authors.initials: M
authors.lastname: Shiraki
authors.forename: H
authors.initials: H
authors.lastname: Orimo
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D001846:Bone Development / Q000502:physiology; D001842:Bone and Bones / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000032:analysis; D002478:Cells, Cultured; D004958:Estradiol / Q000097:blood / Q000494:pharmacology; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005269:Femur / Q000737:chemistry / Q000378:metabolism; D007279:Injections, Subcutaneous; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism* / Q000502:physiology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D015675:Osteocalcin / Q000097:blood; D010052:Ovariectomy; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D013154:Spleen / Q000166:cytology*
chemical_list: D004967:Estrogens; D007375:Interleukin-1; D015675:Osteocalcin; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D002118:Calcium