Novel Androgen Receptor Variant 45 in Brain Tissue

Purpose: A membrane associated androgen receptor has been implicated in the damaging effects of testosterone in neurodegenerative disorders, such as Parkinson’s disease. An androgen receptor variant (AR45) that has a C-terminus and a unique N-terminus has been found in peripheral tissues, such as the heart, skeletal muscle, uterus, and prostate, but has not been found in the brain. Recent findings have shown that a AR45 is present in the membrane fraction of a dopaminergic neuronal cell line (N27). Therefore, we wanted to determine if AR45 was present in cortical, hippocampal, and substantia nigral neurons that are lost during Alzheimer’s and Parkinson’s disease. Methods: In this study we used immunohistochemistry to determine the presence of AR45 presence in rat brain tissue. Tissue sections of 40 um were prepared using a cryostat. The sections were stained with primary antibodies specific for different androgen receptor sequences. The antibodies AR C-19 and AR N-20 were used to identify the C terminus and the N terminus, respectively. Results: Since AR-45 is lacking an N-terminus, we used N-20 antibody that binds to the N-terminus as a negative control. However, AR-45 does have a c-terminus, and thus we used the C-19 antibody as a marker for AR-45. C-19 immunofluorescence was present in the hippocampus, cortex, and substantia nigra. Interestingly, N-20 positive cells were not identified in the substantia nigra, indicating that only AR45 is present in these neurons. Conclusion: This is first study to show the presence of AR45-immunoreactive positive neurons in the brain. Now the receptor has been identified, more research is needed to determine the role of AR45 in neurodegenerative diseases.