Is D-aspartic Acid an Excitotoxin?

I am asking out of mild curiosity and my terribly limited understanding of biological chemistry.

I have read quite a bit on people taking it as a supplement to increase testosterone although in vitro studies are small. I have also read of some using it as a nootropic, but their explanation of the benefits are hazy. I don’t see there being enough evidence yet to support its use for anything, but still I wonder; is d-aspartic acid an excitotoxin?

What ramifcations are these bodybuilders facing by taking this as a supplement on a daily basis? The initial study using Dadavit included B12 - is there any chemical reason for this? Thanks for the info!