Fig 1.
Paw withdrawal latency behavioral changes in response to thermal stimulation after sciatic nerve block with various medications.
* indicates P<0.05 when compared with other groups. # indicates P<0.05 when compared with baseline control. The data were reported as mean ± SEM. NS, normal saline; Bup, bupivacaine; Dexa, dexamethasone; i.m., intramuscularly.
Fig 2.
Motor recovery of mouse sciatic nerve block with various medication.
* indicates P<0.05 when compared with other groups. # indicates P<0.05 when compared with baseline control. The data were reported as mean ± SEM. NS, normal saline; Bup, bupivacaine; Dexa, dexamethasone; i.m., intramuscularly.
Fig 3.
Microscopic changes of sciatic nerves after sciatic nerve block.
3A. istomorphological changes of paraffin-embedded sciatic nerves on day 2 and day 7 after injection (400×, toluidine blue staining). Nerves appeared normal on day 2 and day 7 after injection in most groups, while nerves in the bupivacaine treated group (red box) showed fiber degeneration with vague myelin sheath appearance (arrows) at 2 days after injection; 3B. Percentage of demyelinated axons in sections (n = 5 per group). The percentage of unmyelinated axons in bupivacaine group was significant higher on post-injection day 2 than on day 7 (*P<0.05), while no significant difference was observed in other groups. NS, normal saline; Bup, bupivacaine; Dexa, dexamethasone. Sale bar is at 10μm.
Fig 4.
Caspase-3 expression in sciatic nerves.
4A. Immunohistochemical assays for cleaved caspase-3 staining (200×, nucleus counterstained with hematoxylin). There was no significant caspase expression in sciatic nerve axoplasm in all groups; 4B. Caspase-3 expression in positive control tissue (red arrows) (hippocampal neurons, 200×); 4C. Percentage of nucleus in sciatic nerves. The percentage of nucleus staining (blue arrows) in sciatic nerve was significant higher in bupivacaine treated mice on day 2 than day 7 (red box, *P<0.05), while no significant difference was found in other groups. 4D. Caspase-3 expression in mouse sciatic nerve after bupivacaine and high-dose dexamethasone block (400×). NS, normal saline; Bup, bupivacaine; Dexa, dexamethasone. Scale bar: 45 μm (black color),10 μm (red color).
Fig 5.
S-100 expression in sciatic nerves.
5A. S-100 protein immunostaining in sciatic nerves (200×); 5B. Immunoreactivity of S-100 expression in different treatment groups on day 2 and day 7. Bupivacaine with or without intramuscular dexamethasone treatment group showed significantly lower S-100 expression on day 2 (red box) than that on day 7 (*P<0.05), while S-100 was expressed significantly higher when treated with perineural bupivacaine and high-dose dexamethasone than treated with perineural bupivacaine and low-dose of dexamethasone (#P<0.05); 5C. Immunohistochemical assay for S-100 protein staining (deep brown, black arrows) in each group was primarily localized in the myelin sheath (400×, counterstained with hematoxylin). NS, normal saline; Bup, bupivacaine; Dexa, dexamethasone. Scale bar: 45 μm (black color),10 μm (red color).