title: Bone metabolism in ovariectomized rats with induced hyperthyroidism: the effect of estrogen replacement.
abstract: We aimed to investigate whether or not the estrogen is playing any role in the effect of thyroid hormones on bone metabolism. The rats were divided into five groups. In the first group L-thyroxine-induced hyperthyroid rats were ovariectomized (OVX) while the OVX rats were administered L-thyroxine in the second group. 17beta-Estradiol (E2) was replaced in OVX rats in Group III. L-thyroxine and E2 were simultaneously administered to OVX rats in Group IV. The fifth group received sham operation. Blood samples taken from the tail vein of rats were analyzed for plasma T3, T4, TSH and serum interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)alpha, calcium (Ca), phosphorous (P), parathyroid [corrected] hormone (PTH), alkaline phosphatase (t-ALP), bone-specific alkaline phosphatase (b-ALP) and E2. The levels of cytokines, t-ALP and b-ALP increased but PTH decreased, while there was no change in Ca and P levels in L-thyroxine-administrated rats. However, the levels of cytokines, Ca, P, PTH, t-ALP and b-ALP did not change in L-thyroxine-administered OVX rats. In OVX rats, the cytokines, t-ALP and b-ALP increased while Ca, P remained the same, but PTH decreased. L-thyroxine administration to OVX rats did not change the cytokines, Ca, P, PTH, t-ALP and b-ALP levels. The replacement of E2 in OVX rats decreased the cytokines, t-ALP and b-ALP values, increased PTH levels while there was no change in Ca and P. L-thyroxine and E2 administration to OVX rats increased the cytokines, t-ALP and b-ALP levels and decreased PTH, but Ca and P remained the same. In sham-operated rats, there was no change in all parameters compared to initial values. This study suggests that estrogen may play a role in the effects of thyroid hormones on bone metabolism.
authors.affiliation: Yildiz Technical University, Acts and Science Faculty, Department of Chemistry, Istanbul, Turkey.
authors.forename: Volkan
authors.initials: V
authors.lastname: Sozer
authors.forename: Hafize
authors.initials: H
authors.lastname: Uzun
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Guner
authors.forename: Seval
authors.initials: S
authors.lastname: Aydin
authors.forename: Rifat
authors.initials: R
authors.lastname: Yucel
authors.forename: Yesari
authors.initials: Y
authors.lastname: Karter
authors.forename: Cahit
authors.initials: C
authors.lastname: Simsek
authors.forename: Safiye
authors.initials: S
authors.lastname: Kaya
authors.forename: Gunnur
authors.initials: G
authors.lastname: Yigit
authors.forename: Gonul
authors.initials: G
authors.lastname: Simsek
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000378:metabolism*; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000502:physiology*; D005260:Female; D006980:Hyperthyroidism / Q000378:metabolism*; D053583:Interleukin-1beta / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D010024:Osteoporosis / Q000378:metabolism; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D013974:Thyroxine / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D004967:Estrogens; D053583:Interleukin-1beta; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D013974:Thyroxine