Note also that the Substantia Nigra is one of the most energy-intensive parts of the subcortical brain, probably because it must manufacture and transport the dopamine for other parts of the basal ganglia, or because the Substantia Nigra must continuously fire some of its neurons roughly 25 times per second.
However, with the dopamine system there might be some general vulnerability. Autooxidation of dopamine seems to be a possible problem, in general a vulnerability to oxidative stress. But then after induced oxidative stress in the striatum neurons in the Sn die without signs of oxidative stress, though maybe because of fast clearance of such markers, as Smith and Cass 2007 reason.
The dopamine system might be a good candidate for fatique, indeed, and I completely agree that the article @pattismith provided is very interesting, including that only a portion of PwMS get a MS-fatique, though quite a percentage.
I finally noticed, that in my CFSME selenium may turn out to be most important along with low manganese. This buffles me a bit. Mn is of course well known for its participation in the mitochondrial MnSOD, which convertes superoxide anions to hydrogen peroxide, which is then further processed (in a clearing manner) by gluatahione peroxidase which uses selenium. Could it really be that such an important way can be influenced simply by nutrition? Or is it any receptor side to hydrogen peroxide that would be hypersenstive?
Its complicate pathways anyway, which might be seen in Rodriguez-Rocha et al 2013 who conclude that energy failure and not oxidativee stress - which they investigated - might be the problem (in PD). I think the clue was that stressors in the mt matrix could not be countered by the (mostly in the matrix located) MnSOD, but MnSOD had an effect on a stressor which has additional, other actions.
I think that rather in such area the problem is located, not really in any infection. TSPO has many actions, and is not well understood. This molecule seems to have been investigated also in the MS finding, as the authors only in the disucussion one time mentioned, if I got it rightly. There should be a wide range of interpretation, with TSPO.