Abstract
The present study was undertaken to investigate the correlation between clinical pain and the level of β-endorphin in blood plasma. We measured the concentration of β-endorphin and cortisol in blood plasma of patients with oro-facial pain.
The β-endorphin levels of patients were higher than the levels of healthy volunteers (control group), but it was not significant, whereas, the cortisol levels of patients were significantly higher than control levels. Patients classified as having postoperative pain were found to have significantly higher β-endorphin levels than the control group, but the cortisol levels did not change. The β-endorphin levels in patients with trigeminal neuralgia were lower and the cortisol levels significantly higher than those of the control group. Patients with oro-facial pain were classified into acute and chronic pain group. In the acute pain group, β-endorphin levels were significantly higher than in the control group but the levels in the chronic pain group did not change.
There was a correlation between the clinical pain score and plasma β-endorphin level in the acute pain group but not in the chronic pain group. These results suggest that plasma, β-endorphin increases in case of the transient pain and decreases in case of the continuous pain. Further studies, however, will be necessary to discover whether plasma β-endorphin can play any role in the pain control mechanism.