Degenerative changes of afferent neurons in the lumbosacral dorsal root ganglia following complete urethral obstruction in guinea pigs.

OBJECTIVE

The ultrastructural changes in the bladder afferent neurons were examined in the guinea pig following acute complete urethral obstruction.

MATERIAL AND

METHODS

Complete urethral ligation was carried out in nine guinea pigs under anaesthesia and the animals were sacrificed at 12, 24 and 48 h postoperatively. Three sham-operated animals were sacrificed at 48 h postoperatively as controls. The dorsal root ganglia (DRG) at L6, S1 and S2 spinal segments of the animals in each group were removed and processed for electron microscopic study.

RESULTS

In the control groups, all the DRG neurons at L6-S2 segments appeared normal. At 12 h after urethral ligation, a few neurons in the DRG at various segments showed signs of structural changes, notably the mitochondria. Mitochondrial swelling was more pronounced at 24 h, and by 48 h most of them became vacuolated and lysed. It was estimated by semiquantitative study that 18.6% and 22% of DRG neuronal profiles at 24 and 48 h, respectively, displayed severe mitochondrial swelling and vacuolation.

CONCLUSIONS

The observed degenerative changes in DRG neurons following complete urethral obstruction may be a cellular reaction in response to the axonal injury elicited by bladder overdistension. This may account for alterations in visceral sensation in patients with acute urinary retention.