Binding sites of mu receptor increased when acupuncture analgesia was enhanced by droperidol: an autoradiographic study.

AIM

To study if mu receptor participates in the process of potentiation of droperidol (Dro) on acupuncture analgesia (AA).

METHODS

Autoradiographic technic was used. Ohmefentanyl, a highly selective ligand of mu receptors, was used in radio-receptor binding assay in Sprague-Dawley rat brain sections.

RESULTS

The binding sites of [beta-3H, p-benzoyl-3H]ohmefentanyl were increased greatly in many nuclei of rat brain after AA, and were further increased when AA was enhanced by Dro. Higher increase was seen in caudate nucleus, accumbens, periaqueductal gray (PAG), interpeduncular nucleus, amygdala (P < 0.01 vs rats treated with electroacupuncture alone); moderate increase was noted in thalamus, lateral area of hypothalamus, spinal dorsal horn (P < 0.01 or 0.05); slight increase appeared in septum, preoptic area, hippocampus, substantia nigra (P < 0.05).

CONCLUSION

Mu opioid receptors mediated the Dro-induced enhancement of AA.