Background
Testosterone is reported to have neuroprotective effect in various neurological diseases. Recently, the mechanism involved in nitric oxide (NO)-mediated motor neuron death is under extensive investigation. The Cu/Znsuperoxide dismutase (SOD1) mutations has been implicated in selective motor neuron death of amyotrophic lateral sclerosis (ALS) and it is said to play an important role in NO-mediated motor neuron death. However, neuroprotective effect of testosterone on motor neuron exposed to NO has rarely been studied.
Methods
Motor neuron-neuroblastoma hybrid cells expressing wild-type or mutant (G93A or A4V) SOD gene were treated with 200 μΜ S-nitrosoglutathione. After 24 hr, cell viability was measured by MTT assay. To see the neuroprotective effect of testosterone, pretreatment with 1 nM testosterone was done 1 hr before S-nitroglutathione treatment. To study the mechanism of protective effect, 20 μΜ flutamide (androgen receptor antagonist) was also pretreated with testosterone 1 hr before S-nitroglutathione treatment.
Results
S-nitrosoglutathione showed significant neurotoxic effect in all three cell lines. Percentage of cell death was somewhat different in each cell line. 1 nM testosterone showed neuroprotective effect in G93A and wild-type cell line. In A4V cell line, testosterone did not showed neuroprotective effect. The neuroprotective effect of testosterone was reversed by 20 μΜ flutamide.
Conclusions
These results indicate that testosterone induces neuroprotection in NOmediated motor neuron death directly through the androgen receptor. This neuroprotective effect of testosterone varies according to the types of SOD1 gene mutation. These data suggest that testosterone may be of therapeutic value against ALS.
