The Mechanical Antiallodynic Effect of Intrathecal Lamotrigine in Rats with Spinal Nerve Ligation / 대한통증학회지

ABSTRACT

BACKGROUND: A nerve ligation injury may produce a tactile allodynia. The effects of intrathecally delivered lamotrigine on allodynia induced due to fifth and sixth lumbar spinal nerves ligation in rats, using lumbar intrathecal catheters were examined. METHODS: Sprague-Dawley rats (body weight 160-180 g) were prepared by tightly ligating the fifth and sixth left lumbar spinal nerves, with the implantation of a chronic intrathecal catheter for drug administration. Mechanical allodynia and allodynic threshold were measured using von Frey filaments and the updown method, respectively. After the baseline hind paw withdrawal thresholds had been obtained, lamotrigine (10, 30, 100 and 300microgram) was administered intrathecally. Thereafter, the dose-response curves and 50% effective dose (ED50) were obtained. Motor dysfunction was assessed by observing the righting/stepping reflex responses and abnormal weight bearing. RESULTS: Intrathecal administration of lamotrigine produced a dose-dependent antiallodynic action (ED50 = 61.7microgram). Mild motor weakness was observed with 300microgram lamotrigine, but no severe motor impairment was found. CONCLUSIONS: It is suggested that intrathecal lamotrigine could produce moderate antagonism of mechanical allodynia at the spinal level in a rat neuropathic pain model with minimal motor weakness.