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Osteoblastic cells mediate osteoclastic responsiveness to parathyroid hormone
Endocrinology
|February 1, 1986
Summary
Parathyroid hormone (PTH) stimulates osteoclastic bone resorption indirectly. Osteoblasts mediate this effect, as PTH alone did not increase resorption, but significantly increased it when osteoblasts were present.
Area of Science:
- Bone biology
- Endocrinology
- Cell biology
Background:
- Osteoblastic lineage cells may mediate parathyroid hormone (PTH)-induced bone resorption.
- The precise mechanism of PTH action on bone cells requires further elucidation.
Purpose of the Study:
- To investigate the role of osteoblastic lineage cells in mediating PTH-induced osteoclastic bone resorption.
- To determine if PTH directly affects osteoclasts or acts indirectly via osteoblasts.
Main Methods:
- Osteoclasts were isolated from neonatal rat long bones.
- Osteoclasts were cultured on human cortical bone slices, both alone and co-cultured with osteoblasts.
- Bone resorption was quantified using scanning electron microscopy and morphometric analysis.
Main Results:
- PTH did not affect bone resorption by isolated osteoclasts.
- Co-culture with osteoblasts (including osteosarcoma cells) led to a 2- to 4-fold increase in PTH-induced bone resorption.
- Osteoblastic cells alone did not cause significant bone resorption.
Conclusions:
- PTH primarily acts on osteoblasts, not directly on osteoclasts.
- Osteoblasts, when stimulated by PTH, induce osteoclastic bone resorption.
- This study clarifies the indirect mechanism of PTH action in bone remodeling.