Protection Of Testosterone On Lumbosacral Cord Anterior Horn Motor Neurons

Spinal cord injury (SCI) often leads to lifelong disability of the patient, resulting in suffering of the patient and burden of the family and society. At present there is still no effective therapy. Therefore it is difficult and important to study the pathology and therapy of SCI. In fact the repair of the spinal cord injury aims at preventing the motor neurons from degeneration, in order to keep or recover its function as possible as we can. Testosterone is one kind of sex hormone which could be secreted by the mammalian own. In the recent years, its neuroprotective function is gradually revealed. Here we investigated the protective effect of testosterone on the lumbosacral cord anterior horn motor neurons. We hope the research could give some reference to the therapy of spinal cord injury. Firstly we traced the anterior horn motor neurons whose axons formed the sciatic nerve with 8 % Evans Blue in C57BL/6Slac mice. They were located in the specific lumbosacral cord segments. Then C57BL/6Slac mice were castrated. 1 week later we reconstructed the unilateral sciatic nerve cutting model, the unilateral lumbosacral cord compression model and the unilateral lumbosacral cord incision model. Each animal model was randomly divided into 2 groups: the sesame oil control group and the testosterone experimental group which were given subcutaneous injection of sesame oil or testosterone immediately after the nerve injury operation. The drugs were injected every other day. 2 weeks later the mice were perfused and fixed with saline and paraformaldehyde. The certain lumbosacral cords were taken for slicing. The number and soma area of the anterior horn motor neurons in the lumbosacral cord were then measured on Nissl stained sections.Whatever the motor neurons suffered from the axon or cell body injury on three different nerve injury animal models, the results were the same. In the testosterone group the motor neurons appeared healthier than that in the sesame oil control group. The neurons were plumper and showed more processes. Their number and average soma size were significantly larger than that in the sesame oil control.In conclusion, the findings suggested that testosterone had a significant protection on the motor neurons after injury. Testosterone could not only improve the survival rate of the motor neurons, but also prevented the cell body from atrophy after nerve injury. Therefore, testosterone plays a protective role to the remaining nervous tissue after injury, which is good for the recovery of the motor function. Maybe it could provide a new way to cure the spinal cord injury clinically.