Lidocaine/multivalent ion complex as a potential strategy for prolonged local anesthesia.

Local anesthetics are adopted in clinical practice to manage the perioperative and/or postoperative pain. However, their relatively short duration of action limit their ability to meet clinical needs. Herein, we prepared a lidocaine/multivalent ion complex (icLD) using aqueous solutions containing positively charged LD and a multivalent counter-ion as a system for producing prolonged anesthesia. The results of the in vitro and in vivo experiments indicated that the icLD facilitates prolonged LD release even without adjuvants and thus provides nerve blockade for a long duration of action (∼14h) without further increase in neurotoxicity than the LD itself. These findings suggested that the icLD could be a practical strategy for effectively controlling perioperative and/or postoperative pain in clinical practice.

Shengmai-san-mediated enhancement of regenerative responses of spinal cord axons after injury in rats.

Shengmai-san (SMS) is a traditional Chinese medicine used to treat diverse symptoms including cardiovascular and neurological disorders. Here we investigated the effects of SMS on regenerative responses of spinal cord axons in rats that were given contusion injury at the lower thoracic level. The injury cavity was confined to a restricted area by SMS treatment, and the signals of glial scar protein chondroitin sulphate proteoglycan (CSPG) and inflammatory cell marker protein CD11beta were heavily observed within the injury cavity in SMS-treated animals. Anterograde tracing of DiI-labeled corticospinal tract (CST) axons revealed increases in collateral arborization around and within the injury cavity and caudal elongation by SMS treatment. Furthermore, SMS treatment facilitated neurite elongation of dorsal root ganglion (DRG) sensory neurons that were co-cultured with non-neuronal cells prepared from injured spinal cord. Phospho-Erk1/2 was strongly induced in both spinal cord and motor cortical areas after spinal cord injury (SCI), and it was further unregulated in the motor cortex by SMS treatment. In contrast, upregulation of cell division cycle 2 (Cdc2) production by SMS treatment was limited to a local, SCI area. These data suggest that SMS may play an active role in regenerative responses and facilitate axonal regrowth after SCI.