Role of DLC2 and RhoA/ROCK pathway in formalin induced inflammatory pain in mice

This study investigated the role of DLC2 and its downstream cascade of RhoA/ROCK in formalin-induced inflammatory pain using DLC2-knockout (DLC2-/-) mice and compared them with DLC2 wild-type (DLC2+/+) mice. Mechanical allodynia and thermal hyperalgesia were evaluated using von Frey filament aesthesiometer and Hargreaves test, respectively. The spinal cord dorsal horn (L3-L5) was selected for molecular and cellular identification by Western blot and immunofluorescence. DLC2-/- mice showed increased mechanical allodynia and thermal hyperalgesia. Expression of ROCK1, ROCK2 and IL-1β was significantly higher in DLC2-/- mice. Intrathecal administration of RhoA inhibitor (C3 exoenzyme) or ROCK inhibitor (Y27632) significantly attenuated formalin-induced inflammatory hyperalgesia in DLC2-/- mice. ROCK2 and IL-1β expression were reduced by C3 exoenzyme or Y27632. Spinal p38 activation was also inhibited by C3 exoenzyme or Y27632. Double-labelling immunofluorescence demonstrated co-localization of DLC2 with spinal dorsal microglia. The number of activated microglia in the spinal dorsal horn was significantly higher in DLC2-/- mice, but was reduced by Y27632. These findings indicate that DLC2 deficiency increased formalin-induced inflammatory hyperalgesia through regulating RhoA/ROCK2, and IL-1β may be a downstream effector. Our results also suggest that RhoA/ROCK enhanced p38 activation plays an important role in formalin-induced inflammatory pain. The finding that DLC2 attenuated...
Source: Neuroscience Letters - Category: Neuroscience Source Type: research