[Morphological change and reversibility of major pelvic ganglion neurons using rat model of partial urethral ligation].

We made partial urethral ligation in female Wistar rats to evaluate the morphological change and the reversibility of the major pelvic ganglion (MPG) neurons before and after partial urethral ligation. Thirty rats were divided into 4 groups; normal control group (N = 3), ligation group (N = 9), release of ligation group (N = 9), and sham-operated group (N = 9). WGA-HRP (horseradish peroxidase with lectin wheat germ agglutinin) was injected into the right side of the bladder 4 days before the MPG neurons were removed. MPG was examined by the axonal tracer method. Rats with partial urethral ligation for 1 week exhibited a significant increase in the size (419.1 +/- 146.0 microns2) of the mean area of MPG neurons as compared to the normal controls (318.0 +/- 118.6 microns2), but they showed a steady decrease in size (304.2 +/- 118.6 microns2) similar to that in the sham-operated group (310.2 +/- 116.3 microns2) 3 weeks after the removal of the ligation. The rats with partial urethral ligation for 7 weeks and 11 weeks also exhibited a significant increase in the mean area (7w; 484.1 +/- 192.6 microns2, 11w; 549.4 +/- 181.3 microns2), but they did not show complete recovery (7w; 383.3 +/- 159.6 microns2, 11w; 549.6 +/- 279.5 microns2) as compared to the sham-operated group (7w; 324.4 +/- 124.9 microns2, 11w; 345.9 +/- 121.7 microns2) after removal of ligation. Only the 1-week ligation group showed recovery in neuronal size. These findings imply that the neuronal hypertrophy might become irreversible when the period of partial urethral ligation persisted beyond 7 weeks.