Intrathecal lidocaine elevates prostaglandin E2 levels in cerebrospinal fluid: a microdialysis study in freely moving rats

Abstract

BackgroundIn this study, we have investigated whether intrathecal (i.t.) lidocaine administration is accompanied with changes of cerebrospinal fluid (CSF) prostaglandin E2 (PGE2) levels. MethodsRats were anaesthetized for i.t. implantation of a triple-lumen spinal loop dialysis catheter. CSF changes in PGE2 after i.t. injection of saline, 400, or 1000 μg of lidocaine were measured. The impact of i.t. pretreatment with 5 μg MK801 (N-methyl-d-aspartate glutamate antagonist) or 10 μg SC76309A (COX-2 inhibitor) was also investigated. CSF dialysates for measurement of PGE2 were collected for 4 h. During the whole procedure, motor and sensory blocks were evaluated. A separate group receiving i.t. lidocaine 400 μg (without dialysate sampling) was assessed for mechanical (Von Frey) and radiant heat pain. ResultsPGE2 levels increased to 400% of baseline and remained elevated for 90–120 min after i.t. lidocaine at both doses. Pretreatment with SC76309A and MK801 attenuated this increase. A 40 min period of enhanced pain response was observed after Von Frey filament stimulation during and after sensory and motor block recovery. ConclusionsI.T. lidocaine (400 or 1000 μg) increases PGE2 levels in the CSF for 90–120 min along with a transient period of mechanical hyperalgesia after sensory and motor block recovery.