Our previous studies have demonstrated that some male patients suffering from brachial plexus injury, particularly brachial plexus root avulsion, show
erectile dysfunction to varying degrees. However, the underlying mechanism remains poorly understood. In this study, we evaluated the erectile function after establishing brachial plexus root avulsion models with or without
spinal cord injury in rats. After these models were established, we administered
apomorphine (via a
subcutaneous injection in the neck) to observe changes in erectile function. Rats subjected to simple brachial plexus root avulsion or those subjected to brachial plexus root avulsion combined with
spinal cord injury had significantly fewer erections than those subjected to the
sham operation. Expression of
neuronal nitric oxide synthase did not change in brachial plexus root avulsion rats. However,
neuronal nitric oxide synthase expression was significantly decreased in brachial plexus root avulsion +
spinal cord injury rats. These findings suggest that a decrease in
neuronal nitric oxide synthase expression in the penis may play a role in
erectile dysfunction caused by the combination of brachial plexus root avulsion and
spinal cord injury.