has a brief explanation of LDN action based on previous work by Dr. Zagon and may also be what happens with low-dose DM. It goes something like this:
The small dose of of this opioid antagonist blocks certain opioid receptors for a short period of time just before the period of sleep in which the endorphins such as methionine enkephalin are produced by the adrenal and pituitary glands. This short inhibition stimulates increased production of endorphins and their opioid receptors in the brain.

If you want to read the actual text, here is the link to the site.
http://www.lowdosenaltrexone.org/index.htm
Since the endorphins and enkephalins are our natural "feel good" hormones, and are involved in regulating a varitey of cells of the immune system such as brain microglia, this combination of effects may be at the bottom of both Steve's lift in mood and the neuroprotection we are hoping for.
Robert