Both of the first two studies used continuous dosing of rapamycin, which we already know can cause problems by inhibiting mTORc2. Intermittent dosing, as performed in this study:
Intermittent Administration of Rapamycin Extends the Life Span of Female C57BL/6J Mice
https://academic.oup...1/7/876/2605199
and by most people who are trying this on themselves, seems to largely avoid this problem, and perhaps also the toxicity found in those studies.
The last study doesn't say that the detrimental results of the first two necessarily would be ameliorated by metformin. It's studying damaged caused by physical stress.
Slow down cowboy and read my part before you get excited: "The main thing I'm getting from this and similar studies is that you should not start while young or try to conceive while on rapamycin; and, you should not dose continuously and have plenty of breaks unless you are treating a disease and are willing to face possible detrimental side effects."
"[W]hich we already know can cause problems by inhibiting mTORc2;" and yet I see PLENTY of people reporting mTORc2 side effects by trying to push to and hold the edge. mTORc2 isn't a switch, it is some kind of gradient just like the putative 50% mTOR1 suppression at 5mg raising 10%ish per mg.
Long term edge riding is not necessarily safe from some level of mTOR1c interference nor would it effect everyone the same. We should not be afraid to discuss the serious consequences if you get it wrong, especially for "younger" people.
Further, cataracts and testicular degeneration are no joke (we've already had people report eye issues and reduce sex drive here); and people with autoimmune issues can also get triggered by the immune boost. Finally just because it piles on everything, covid can raise antinuclear antibodies (possible the source of long covid), as can age, so there may be more of us with mild autoimmune issues than we know.
I've been following your high on / long off regimen with great interest since the body handles acute insults much better than chronic ones. Your noticing that effects lasted long after the dose had cleared tracks with some of the single dose papers. Have you had an ANA blood test and if so, have there been any changes?
I'm wondering if rapamycin does an ISR reset similar to ISRIB and possible quercetin. (I won't go into it but very exciting work: Drug Reverses Age-Related Mental Decline Within Days - UCSF)
The last study is Rifampicin not Rapamycin (don't mix the two - sorry for the typo) but should be of interest to some one with cognitive issues, like say PA.
As for Metformin (aka Goat's rue if you can't get it otherwise) again, please actually read what I said before going off.
I never said Metformin would "ameliorate" anything in the first two studies. What I said was: "Metformin does seem to be synergetic (I'd love to see a test of rapamycin and berberine) and help with glucose rise from side effect level dosing."