GENDER DIFFERENCES IN AUTOTOMY FOLLOWING SCIATIC CRYONEUROLYSIS IN THE RAT

Gender differences reported in nociceptive and nerve injury research s hould be considered before conclusions about basic pathologic mechanis ms are drawn. Holtzman male rats are routinely used in the mononeuropa thy model produced by a peripheral nerve freeze lesion, sciatic cryone urolysis (SCN). SCN reproducibly results in abnormal behaviors which i nclude autotomy, the gnawing and scratching of the affected hindpaw. I n the present studies, the incidence and severity of autotomy 1 to 21 days following SCN was compared in male and female Holtzman rats. Fema le Holtzman rats displayed a decreased incidence and severity of autot omy 7 days and beyond following SCN. This disparity was statistically different at 14 days (p < 0.01) and at 21 days (p < 0.05) by Newman-Ke uls test. Morphometric comparison of the sciatic nerve at the lesion s ite in male and female rats 14 days post-SCN (time of peak autotomy be havior in this model) displayed differences in the fascicular percenta ge of edema (p < 0.01) and remyelinating axons (p < 0.05) between gend ers using Student's t-test. However, these percentage values did not c orrelate with either the incidence or severity of autotomy scores for those animals. Therefore, biochemical differences at and/or proximal t o the peripheral nerve freeze lesion may be responsible for mechanisms which generate or relate to autotomy.