The influence of irradiation on the potential chondroprotective effect of aqueous extract of propolis in rats.

PURPOSE

Cartilage degradation usually results as a consequence of inflammatory processes in the joints. To study this phenomenon experimentally, adjuvant-induced arthritis (AIA) was used as a model of chronic inflammation under the influence of irradiation. The potential chondroprotective effect of 13% aqueous extract of propolis (AEP) in arthritic rats was investigated.

MATERIALS AND METHODS

The influence of whole body irradiation on the arthritic inflammatory response was investigated by subjecting rats to a Gamma source before the induction of arthritis. 13% AEP was injected intraperitoneally in a dose of 5 ml/kg and diclofenac was used as reference non-steroidal anti-inflammatory drug (NSAID) in a dose of 3 mg/kg. The chosen parameters for cartilage integrity were glycosaminoglycan (GAG), hydroxyproline contents in cartilage and cartilage oligomeric matrix protein (COMP) in serum. The serum levels of tumour necrosis factor-alpha (TNF-α), nitric oxide (NO) and the oxidative stress biomarkers such as blood glutathione (GSH) and plasma malondialdehyde (MDA) levels.

RESULTS

Induction of arthritis led to a reduction in GAG and hydroxyproline content of femoral cartilage and a corresponding rise in COMP in serum. Previous exposure to irradiation resulted in a milder reduction of GAG and hydroxyproline and a lesser rise in COMP. Treatment of arthritic irradiated and non-irradiated rats with 13% AEP markedly prevented the breakdown of cartilage in a much more effective manner than diclofenac. Both AEP and diclofenac were equipotent in reducing the level of TNF-α and were able to normalize NO and the oxidative stress biomarkers in non-irradiated and irradiated arthritic rats.

CONCLUSION

The ability of propolis to protect cartilage degradation could therefore prove of value in the treatment of chronic arthritic diseases, offering an advantage over some NSAID, particularly those with a potential detrimental effect on cartilage integrity.