Pain reduction by electrical stimulation of your central grey matter in humans and its reversal by naloxone. Very little is known regarding how these stimuli activate nociceptors. The nociceptive nerve endings are so modest and scattered that they're hard to obtain, let alone examine. However, there are some studies https://www.proleviate.com/post/conolidine-blocks-ackr3-pain-receptors-in-what-way