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Chondrocytic monoamine oxidase activity in the development of natural murine osteoarthritis
M G Chambers1, M K Jasani, L Bitensky
1Unit of Cellular Pharmacology and Toxicology, Robens Institute of Health and Safety, University of Surrey, Guildford, UK.
Abstract:
Most of the male STR/ORT mice develop osteoarthritis (OA) involving the medial tibial plateau. A peculiarity of two chondroprotective drugs is the presence of a nitrogen atom so that cleavage of the molecule could generate a molecule that might act as an inhibitor of monoamine oxidase (MAO). Direct examination showed abnormal localization of MAO in the potentially osteoarthritic cartilage indicating possible abnormal response to catecholamines. In normal cartilage, the direct effect of excessive concentration of adrenaline caused considerable oedema, as measured by microscopic interferometry. It is therefore suggested that the excess of water found in the matrix of osteoarthritic cartilage may be related to disturbance of the MAO activity.
Insights
Osteoarthritis (OA) in mice may involve abnormal monoamine oxidase (MAO) activity in cartilage. This disturbance could relate to excess water content in osteoarthritic cartilage, impacting catecholamine response.
Area of Science:
- Biochemistry
- Orthopedics
- Pharmacology
Background:
- Male STR/ORT mice spontaneously develop osteoarthritis (OA), primarily affecting the medial tibial plateau.
- Certain chondroprotective drugs contain a nitrogen atom, suggesting potential cleavage into monoamine oxidase (MAO) inhibitors.
- Abnormal MAO localization in osteoarthritic cartilage suggests a possible link to catecholamine metabolism.
Purpose of the Study:
- To investigate the role of monoamine oxidase (MAO) in the development of osteoarthritis (OA).
- To explore the potential connection between MAO activity, catecholamine response, and cartilage water content in OA.
Main Methods:
- Direct examination of MAO localization in osteoarthritic cartilage.
- Microscopic interferometry to measure cartilage swelling (edema) in response to adrenaline.
- Analysis of potential MAO inhibition by drug metabolites.
Main Results:
- Abnormal localization of MAO was observed in cartilage prone to OA.
- Excessive adrenaline concentrations induced significant edema in normal cartilage.
- A correlation between disturbed MAO activity and excess water in osteoarthritic cartilage matrix is suggested.
Conclusions:
- Disturbed monoamine oxidase (MAO) activity may contribute to osteoarthritis (OA) pathogenesis.
- Abnormal MAO localization and function could underlie the altered water content observed in OA cartilage.
- Further research into MAO's role may reveal novel therapeutic targets for OA.