Injection of ropivacaine into the subarachnoid changes the ultrastructure and proteome of the rat spinal cord

1. In the present study, we investigated the impact of 1.0% ropivacaine on the ultrastructure and proteome of the rat spinal cord. 2. Rats received three injections (90-min intervals, 0.2 mL/kg) of 0.9% NaCl, 0.5% ropivacaine or 1.0% ropivacaine via an implanted intrathecal catheter. Transmission electron microscopy was performed to exam the ultrastructure of the spinal cord. Two-dimensional electrophoresis followed by mass spectrometry identification were carried out to investigate the proteome. 3. In the rats administered 1.0% ropivacaine, deformed organelles, detached myelinated nerve fiber layer, and incomplete inner and outer shaft membranes were observed in the spinal cord and posterior root shrunken nuclei. Furthermore, in the rat spinal cord 1.0% ropivacaine induced the down-regulation of voltage-dependent anion channel 2 (VDAC2) and mitochondrial pyruvate dehydrogenase subunit alpha (ODPA), the upregulation of myelin basic protein (MBP), the disappearance of myelin transcription factor 1 (MYT1) and the appearance of heat shock protein 25 (HSP25). Little change was observed in the 0.5% ropivacaine or control groups. 4. Our results suggest that 1.0% ropivacaine treatment led to neurotoxicity, as shown by ultrastructural and proteomic changes in the rat spinal cord. Specific proteins were identified that are implicated in 1.0% ropivacaine-induced neurotoxicity.