尿道狭窄ラットにおけるMajor pelvic ganglion(MPG)ニューロンの形態学的変化とその可逆性についての検討

Abstract

下部尿路通過障害による末梢神経系の変化を明らかにする目的でラットの尿道狭窄モデルを作製し, MPGニューロンの形態学的変化を観察し, 同時に膀胱重量, 体重を測定した。1) mean areaは1週間狭窄群では狭窄解除後正常化したが, 狭窄が7週間以上におよぶと期間の長さとともに増大し, 解除後も正常化しなかった。2)膀胱重量は1週間狭窄群は解除後ほぼ正常化したが7週間狭窄群, 11週間狭窄群は解除後も正常化しなかった。3)尿道狭窄ラットのMPGニューロンの肥大化, 膀胱重量の変化は7週間以上の狭窄で不可逆的になる可能性が示唆された

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.