DMT is naturally found in your body, and it shares a close resemblence to serotonin. New evidence suggests that like Thujone (Absinthe's active psychedelic), although closely resembling THC, does not attach to cannaboid receptors. Similarly it has been assumed that the role of DMT is based around the 5HT-2A receptor, new evidence has shown that it may indeed work in an anxiolyctic fashion on the brains trace amine receptors.
It's natural to your body, but so are endogenous opiates and cannabinoids, of course you're not really bron with delta 9 in your CB receptors, and I haven't found any information about the LD 50 of the chemical. When you think about it thought, just try to overdose and see if you can... I don't think it's possible, you'd be too fucked up.
LSD is more potent, although DMT has a much quicker onset, and other distinctive features.