title: Responsiveness of gene expression markers of osteoblastic and osteoclastic activity to calcitonin in the appendicular and axial skeleton of the rat in vivo.
abstract: We have previously shown that calcitonin (CT), an inhibitor of bone resorption, increases vertebral, but not femoral bone density in the rat. To address the physiologic responses associated with these effects on bone mineral density (BMD), we assessed mRNA transcripts reflecting activities of osteoblasts (type I collagen, osteocalcin, osteopontin, and alkaline phosphatase), osteoclasts [tartrate-resistant acid phosphatase (TRAP)], and cell proliferation (histone H4) in the spine and femur of these rats. CT increased spine BMD while increasing type I collagen and decreasing TRAP and histone mRNAs. In the femur, where CT had no effect on BMD, it decreased type I collagen and histone H4 mRNA but did not affect TRAP. CT had no effect on the gene expression of osteocalcin, osteopontin, or alkaline phosphatase at either site. The results indicate that selective alterations in gene expression, as reflected by steady state mRNA levels, are consistent with the changes observed by BMD measurement, and can more clearly define the specific contribution from osteoblast and osteoclast activity. This study demonstrates a heterogeneity in response of the axial and appendicular skeleton to CT, reflected by alterations in gene expression that provide a basis for understanding the observed BMD responses to various pharmacologic interventions.
authors.affiliation: Department of Orthopedics, University of Massachusetts Medical Center, Worcester 01655.
authors.forename: L G
authors.initials: LG
authors.lastname: Jenis
authors.forename: B
authors.initials: B
authors.lastname: Ongphiphadhanakul
authors.forename: L E
authors.initials: LE
authors.lastname: Braverman
authors.forename: G S
authors.initials: GS
authors.lastname: Stein
authors.forename: J B
authors.initials: JB
authors.lastname: Lian
authors.forename: R
authors.initials: R
authors.lastname: Lew
authors.forename: D T
authors.initials: DT
authors.lastname: Baran
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D002116:Calcitonin / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D003094:Collagen / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D005269:Femur / Q000737:chemistry / Q000166:cytology / Q000196:embryology; D005786:Gene Expression Regulation / Q000187:drug effects; D006023:Glycoproteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D006632:Histamine / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D008297:Male; D010006:Osteoblasts / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D015675:Osteocalcin / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D010010:Osteoclasts / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013131:Spine / Q000737:chemistry / Q000166:cytology / Q000196:embryology
chemical_list: D006023:Glycoproteins; D012333:RNA, Messenger; C024229:osteopoietin; D015675:Osteocalcin; D006632:Histamine; D002116:Calcitonin; D003094:Collagen; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase