SummaryThe objective of this study was to evaluate the effects of [D-Ala2, Nme-Phe4, Gly5-ol] enkephalin (DAMGO), a μ-opioid receptor agonist, and β-funaltrexamine (β-FNA), a μ-opioid receptor antagonist, on the biosynthetic capabilities of canine chondrocytes cultured in the presence of interleukin-1 β (IL-1 β). Articular chondrocytes were harvested from the humeral heads of three adult dogs and cultured in a three-dimensional (3-D) gel medium made from low-melting agarose and cell culture medium. Chondrocytes in 3-D culture were exposed to IL-1 β (0 or 20 ng/ml), DAMGO (0,0.1,1.0, or 10 μM), and β-FNA (0 or 10 μM) by addition to the liquid media in all possible combinations. On days five and 15 of 3-D culture, liquid medium samples were harvested for subsequent analysis of glycosaminogly- can (GAG), prostaglandin E2 (PGE2) and matrix metalloprotease-3 (MMP-3) content. On the same days, gel plugs were also harvested and evaluated for GAG content.Incubation with IL-1 β decreased the amount of GAG in the gel plugs and caused an increase in PGE2 production on days five and 15 of 3-D culture. Treatment with DAMGO or β-FNA did not significantly modulate PGE2 production, MMP-3 production, GAG loss to the medium or GAG content of the gel plugs on either day five or 15 of 3-D culture in the presence or absence of IL-1 β. We concluded that DAMGO and β-FNA had neither protective nor detrimental effects on the biosynthetic capabilities of chondrocytes in the presence or absence of IL-1 β.
Molecular dynamics simulations of the δ-opioid receptor agonist and antagonist to suggest conformational change from inactive to active states
