Lidocaine Prevents Referred Hyperalgesia Associated With Cystitis

Aims: Lidocaine produces analgesia by inhibiting excitation of nerve endings or blocking impulse conduction in peripheral nerves. This study was performed to determine whether intrathecal or intravesical administration of lidocaine prior, or subsequent, to induction of chemical cystitis in rats would block referred mechanical hyperalgesia. Methods: Intrathecal or intravesical lidocaine was administered 15 (intrathecal) or 30 (intravesical) min before intravesical instillation of saline or 1 mM acrolein (400 mu l) or 4 hr after saline or acrolein instillation in female Wistar rats. Mechanical sensitivity of hind paws was determined at 24 hr prior to any treatment (baseline) and, 4, 24, and 48 hr after intravesical instillation of acrolein or saline. Also, nerve growth factor (NGF) content was measured in bladder and dorsal root ganglia (DRG). Results: Pre-treatment with intrathecal or intravesical lidocaine attenuated acrolein-induced referred mechanical hyperalgesia of the hind paws. Lidocaine administered after acrolein instillation did not alter referred hyperalgesia. Lidocaine treatment prior to or after induction of cystitis reduced NGF content in the bladder. Conclusions: These results indicate that pre-treatment with lidocaine attenuates referred hyperalgesia associated with cystitis. Lidocaine treatment 4 hr after induction of cystitis failed to prevent referred hyperalgesia despite a similar decrease in bladder NGF. Neurourol. Urodynam. 28:455-460, 2009. (C) 2009 Wiley-Liss, Inc.