[Distribution of rats' pelvic muscles motoneurons innervated by artificial somatic-autonomic reflex arc]

To investigate the distribution of rats' pelvic muscles motoneurons innervated by artificial somatic-autonomic reflex are.

Thirty-five SD rats were randomly divided into normal group (n = 10) and model group (n= 25). The rats in the normal group were given no treatment. In the normal group, the artificial somatic-autonomic reflex arc was established. Six months after establishing the model, external urethral sphincter (EUS), ischiocavernosus (IC), bulbocavernosus (BS) and external anal sphincter (EAS) of the rats in normal group (n = 10) and of the rats in model group A (n = 20) were injected with fluoro-gold (FG). The reversal neural tracing was done. FG positive neural cells were observed by fluorescent microscope. Malt agglutinator binding horseradish peroxidase (WGA-HRP) was injected into L4 spinal cord of the rats in model group B (n = 5) as the anterograde tracer. After being treated with TMB-HRP reaction, the axon endings in the neuromuscular junction in pelvic striated muscles (EUS, IC, BS, EAS) were investigated with light microscopes.

In normal group, EUS and IC injections resulted in transport of FG to neurons in the dorsolateral nucleus (DL) of the ventral horn of the L5-S1, and BS and EAS in the dorsomedial nucleus (DM) of ventral horn in the L5-S1. In the model group A, EUS, IC, BS and EAS injections resulted in transport of FG to neurons in the left ventral horn in the L4. In model group B, after WGA-HRP was injected into the L4 left ventral horn, HRP positive axon terminals were observed in the EUS, IC, BS and EAS.

In the normal rats, the pelvic striated muscles motoneurons locate in the ventral horn of L5-S1. In the model rats, the pelvic striated muscles motoneurons innervated by artificial somatic-autonomic reflex arc locate in the ventral horn of the L4. After the artificial somatic-autonomic reflex arc is established, the isomerous nerve fiber innervates EUS, IC, BS and EAS.