Ferrini F, Trang T, Mattioli TA, Laffray S, Del’Guidice T, Lorenzo LE, Castonguay A, Doyon N, Zhang W, Godin AG, Mohr D, Beggs S, Vandal K, Beaulieu JM, Cahill CM, Salter MW, De Koninck Y (2013) Morphine hyperalgesia gated through microglia-mediated disruption of neuronal Cl(-) homeostasis. Nat Neurosci 16(2):183-192. doi: 10.1038/nn.3295
Summary: Although morphine is the drug of choice in dealing with chronic pain, it paradoxically can produce a hyperalgesic state. The authors examined the issue from several different angles. One method was to eliminate spinal microglia of rats through the intrathecal application of 16-32 μg of Mac-1-SAP (Cat. #IT-33). 20 μg of saporin (Cat. #PR-01) was used as a control. It was found that P2X4 receptors expressed by microglia were necessary for the development of morphine hyperalgesia, but not morphine tolerance.