Morphine, but not methadone, inhibits microsomal prostaglandin E synthase-1 and prostaglandin-endoperoxide synthase 2 in lipopolysaccharide-stimulated horse synoviocytes.

The research investigates the effects of morphine and methadone, types of opioids, on inflammation in horse joint cells, finding that morphine, but not methadone, can reduce an increase in inflammatory markers.

Objective and Background Information

• The primary aim of the study was to explore the impact of two opioids, namely morphine and methadone, on inflammation in lipopolysaccharide-stimulated synoviocytes, which are cells resident in joints, by focusing on microsomal prostaglandin E synthase-1 (mPGES-1) and prostaglandin-endoperoxide synthase 2 (PTGS2) expression.
• As a backdrop to the research, the authors mention that osteoarthritis is among the main locomotor disorders in horses and is commonly treated with nonsteroidal anti-inflammatory drugs. However, recent studies pointed to the potential effectiveness of opioids in anti-inflammatory and analgesic roles.

Methodology

• Synoviocytes were extracted from the distal limb joints of deceased animals for use in the study.
• Using a cell viability assay with crystal violet dye, the researchers checked the cytotoxic effects of lipopolysaccharide (LPS), morphine, and methadone.
• The treatment groups were arranged as follows: synoviocytes treated with only LPS, LPS plus morphine, or LPS plus methadone, for 3, 6, and 12 hours. Afterwards, the levels of mPGES-1 and PTGS2 expression were evaluated using a real-time polymerase chain reaction (PCR) procedure.

Findings

• Results from the cell viability assay showed that both LPS and morphine did not affect the viability of the synoviocytes, even at high concentrations.
• LPS treatment caused an increase in the expression of both mPGES-1 and PTGS2, the molecules implicated in inflammation.
• Morphine was found to inhibit the increase of both mPGES-1 and PTGS2 expression in LPS-stimulated synoviocytes.
• On the other hand, methadone did not have an inhibitory effect on the expression of mPGES-1 or PTGS2.

Implications

• The study’s findings imply that morphine could demonstrate an anti-inflammatory effect since it inhibited the boost in mPGES-1 and PTGS2 expression in inflamed synoviocytes.
• Based on these results, morphine could potentially be useful in treating osteoarthritis, although further studies are needed to confirm this therapeutic role.