| Project/Area Number |
13671168
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Endocrinology
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| Research Institution | University of Occupational and Environmental Health |
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Principal Investigator |
OKADA Yosuke school of medicine, first department of internal medicine, assistant professor, 医学部, 講師 (80333243)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Yoshiya school of medicine, first department of internal medicine, Professor, 医学部, 教授 (30248562)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2002: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2001: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | cyclooxygenase-2 / bone metabolism / osteoblast |
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| Research Abstract |
Studies on mice with disruption of the cyclooxygenase-2 (COX-2) gene have shown that prostaglandins produced by COX-2 are critical for the maximal stimulation of osteoclast differentiation. The current study examined the role of COX-2 in osteoblastic differentiation. Endogenous PGE_2 production was markedly decreased in marrow stromal cell (MSC) cultures from 5-6 wk old mice with disruption of both COX-2 alleles (COX-2^<-/->) compared to cultures from wild type littermates (COX-2^<+/+>). MSC cultures from COX-2^<-/-> mice had decreased alkaline phosphatase (ALP) staining and activity, osteocalcin mRNA expression, and von Kossa staining compared to COX-2^<+/+> cultures. Addition of PGE_2 to COX-2^<-/-> MSC cultures reversed differences in differentiation between COX-2^<+/+> and COX-2^<-/-> cultures. In MSC cultures from mice with only one COX-2 gene disrupted (COX-2^<+/-> mice), PGE_2 production and ALP staining were decreased compared to COX-2^<+/+> cultures. Hence, COX-2^<+/-> mice might be used as models to study COX-2 deficiency in adult mice, thereby avoiding potentially confounding effects of renal abnormalities in COX-2^<-/-> mice on bone metabolism. In vivo, there was a 9% decrease in tibial bone mineral content (BMC) in 3 mo old COX-2^<-/-> and COX-2^<+/-> mice compared to COX-2^<+/+> mice and a 10% decrease in femoral BMC in COX-2^<-/-> mice compared to COX-2^<+/+> mice. Dynamic histomorphometric analyses comparing COX-2^<+/-> mice with COX-2^<+/+> mice suggested decreased bone formation in COX-2^<+/-> mice. We conclude that the absence of COX-2 expression markedly impairs osteoblastic differentiation in vitro and may decrease bone formation more than resorption in vivo.
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