Concurrent bullatine A enhances morphine antinociception and inhibits morphine antinociceptive tolerance by indirect activation of spinal κ-opioid receptors
Acute bullatine A and dynorphin A additively enhance morphine antinociception. Chronic bullatine A and dynorphin A induce no antinociceptive tolerance. Concurrent bullatine A and dynorphin A inhibit morphine antinociceptive tolerance. Bullatine A antinociception/anti-tolerance are mediated by spinal microglial dynorphin secretion. Our data provide basis for concurrent use of aconitines and morphine in analgesia.