Expression of genes for estrogen receptors α and β in human articular chondrocytes

Objective: To investigate the gene expression of estrogen receptor (ER) alpha and ER beta in human articular chondrocytes. Methods: 16 articular cartilage specimens were obtained from 15 patients during surgery. Three of the specimens were from men and 13 from women; three from hip joints and 13 from knee joints; four were normal and 12 showed osteoarthritic cartilage. Total RNA was extracted from the articular chondrocytes and the expression of both ER alpha and ER beta genes was investigated by the reverse transcription-polymerase chain reaction (RT-PCR) method. Results: Gene expressions of ER alpha were detected in all specimens and those of ER beta were found in 15 specimens by the RT-PCR method. There was a significant correlation between the amounts of ER alpha and ER beta. Expression levels of both genes were significantly higher in men than in women. There were no significant differences in the expression levels of both ER genes between the hip and knee joint sites, nor between normal and osteoarthritic tissues. Conclusion: This study is to our knowledge the first to demonstrate the gene expression of both ER alpha and ER beta in human articular chondrocytes. Since there are some functional differences between the two receptors, the effects of estrogen on cartilage metabolism should be elucidated by two different receptor mechanisms. (C) 1999 OsteoArthritis Research Society International.