The authors suggest this could be due to the drug - use causing progressive damage of serotonin neurons. (everywomanover29.com)
What about users of other street drugs or even medications that may also damage serotonin neurons? (everywomanover29.com)
Prostaglandin signaling in serotonin neurons was not required for aversive responses to high temperatures, suggesting that this pain - aversive signaling pathway is specific to inflammatory pain. (sciencedaily.com)