Pain reduction by electrical stimulation from the central grey make any difference in human beings and its reversal by naloxone. Absolutely nothing is understood about how these stimuli activate nociceptors. The nociceptive nerve endings are so modest and scattered that they are tricky to locate, not to mention analyze. https://finnczsiz.livebloggs.com/35981408/what-are-pain-receptors-no-further-a-mystery