• Li-Ya Qiao and Melisa A Gulick.
• Department of Physiology, Box 980551, Virginia Commonwealth University, Richmond, VA 23298-0551, USA. lqiao2@vcu.edu
• Am. J. Physiol. Regul. Integr. Comp. Physiol. 2007 Mar 1; 292 (3): R1368-75.

AbstractChronic inflammation of the urinary bladder generates hyperalgesia and allodynia. Growing evidence suggests a role of ERK in mediating somatic and visceral pain processing. In the present studies, we characterized and compared the activation of two ERK isoforms, ERK1/2 and ERK5, in micturition pathways, including the urinary bladder, lumbosacral dorsal root ganglia (DRG), and spinal cord in adult female and male rats before and after cyclophosphamide (CYP)-induced bladder inflammation. Results showed differential activation of ERK1/2 and ERK5 in these regions following cystitis. The level of phospho-ERK1/2 but not phospho-ERK5 was increased in the urinary bladder; the level of phospho-ERK5 but not phospho-ERK1/2 was increased in DRG; and the level of phospho-ERK1/2 but not phospho-ERK5 was increased in lumbar spinal cord following cystitis compared with control. Cystitis-induced upregulation of phospho-ERK1/2 and phospho-ERK5 was time dependent and showed similar patterns in female and male rats. The level of phospho-ERK1/2 in bladder was increased at 2 and 8 h after CYP injection; the level of phospho-ERK5 in DRG was increased at 8 and 48 h after CYP injection; and the level of phospho-ERK1/2 in lumbar spinal cord was increased at 48 h after CYP injection. The result that phospho-ERK5 was exclusively increased in DRG neurons, while phospho-ERK1/2 was increased in the spinal cord and the urinary bladder after cystitis, suggests a region-specific effect of neurotrophins on micturition pathways following bladder inflammation.

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