尿道狭窄ラットにおけるMajor pelvic ganglionニューロンの形態および膀胱の組織学的構築の変化についての検討

Abstract

ラットの尿道狭窄モデルを作製し, ニューロンの形態学的変化, 膀胱の組織学的変化を観察し比較検討した。1)膀胱重量は1週間狭窄群は解除後ほぼ正常化したが, 4, 7, 11, 20週間狭窄群は解除後, 正常化しなかった。2) 1～4週間の尿道狭窄で, MPGニューロンの形態は狭窄解除6週間以内で可逆的であった。膀胱平滑筋/結合組織の比率(ADsc値)は狭窄後増大したが, 狭窄解除後は平滑筋の縮小, 線維成分の増加を認めた。3)狭窄期間が7週間以上におよぶと, MPGニューロンの形態は狭窄解除6週間後も不可逆的であった。ADsc値も正常化を認めなかった

Ninety six rats were divided into 4 groups (normal control group (N = 4), ligation group (N = 20), ligation-removed group (N = 36), and sham surgery group (N = 36)). The neuronal size of the 4-week ligated rats returned to normal 6 weeks after removal of the ligation. Rats ligated for 7, 11 and 20 weeks also exhibited a significant increase in the mean area but they could not make a complete recovery after removal of ligation for 6 weeks. Only the rats in the 1- and 4-week ligation groups could recover their neuronal size. Area densities of smooth muscle: connective tissue (ADsc ratio) was calculated using Elastica van Gieson staining sections of bladder strips. When ligation was removed, the ratio dropped and became nearly equal to the value of the sham surgery group. Only the 7-week group showed a lower ADsc ratio than the sham surgery group after the ligation was removed. These findings suggest that the reversibility of neuronal hypertrophy might become irreversible when the period of partial urethral ligation persisted beyond 7 weeks. Irreversible hypertrophy of major pelvic ganglion (MPG) neurons might be greatly related with the irreversibly enlarged fibrous bladder which could not show the same ADsc ratio as was seen in the sham surgery groups.