Intrathecal morphine reduces allodynia after peripheral nerve injury in rats via activation of a spinal A1 adenosine receptor.
Zhang Y, Conklin DR, Li X, Eisenach JC. Intrathecal morphine reduces allodynia after peripheral nerve injury in rats via activation of a spinal A1 adenosine receptor. Anesthesiology. 2005 Feb; 102(2):416-20.