Strain differences in peripheral-nerve regeneration in rats

Currently, several strains of rats are used for studies of peripheral-nerve injury and repair. The purpose of this study was to determine if significa nt differences in regeneration between strains exist that might influence c omparison of results and interpretation of scientific conclusions. One outb red (Sprague-Dawley) and four inbred stains (ACI, Wistar-Furth, Lewis, Brow n-Norway) were studied. Animals were randomized to one of two experimental conditions, undergoing either posterior tibial nerve transection and repair , or Silastic conduit repair of the posterior tibial nerve (n=6/group). End point evaluations at 6 and 13 weeks included histomorphometry and walking-t rack analysis. Evidence of excellent regeneration was noted in all rat strains undergoing primary repair. Generally, no statistically significant differences between strains were noted, regardless of endpoint evaluation used in the primary repair group. Nerve regeneration across the conduits was either poor or not present at 6 weeks, with no regeneration at all noted in any animals in th e ACI and Brown-Norway groups, and regeneration in only one or two animals in the other strains. At 13 weeks, between three and five animals in each s train showed regeneration, but functional recovery was poor. Overall, few d ifferences in peripheral-nerve recovery appear to exist between rat strains . It seems that uniform conclusions may be drawn regardless of strain used.