β-endorphin is an agonist of the opioid receptors. It is a short peptide, resulting from processing of the precursor proopiomelanocortin (POMC). In the present study, the in vitro effect of β-endorphin stimulation on human articular chondrocytes was investigated. The primary cultures of articular chondrocytes from knee joint cartilage obtained at total knee replacement of patients with osteoarthritis were treated with β-endorphin at a concentration of 600 ng/ml for 0.5, 1, and 3 hours. Total cell lysates were collected for western blotting to analyse the signal molecules. Following stimulation of β-endorphin for 30 min protein Erk 1/2 showed significantly increased phosphorylation (1.5±0.206), which was inhibited by U0126, a specific inhibitor of MEK. Returned to basal level following 1 and 2 hours stimulation was noted. This effect was abolished by EGTA, an extracellular calcium ion chelator. Increased Erk 1/2 phosphorylation in the short term stimulation of β-endorphin may be beneficial for chondrocyte activity. The subsequent effect on chondrocytes will be further carried out.
Disclosure: The authors declared no competing interests.