Okay but the question was never if subcutaneous injections of capsaicin produce a pain reaction, nor how the effects of neonatal exposure to capsaicin effect the development of a rats life (even if there are impacts on the sensitivity of a response in TRPV1 as a result, your second link pretty clearly establishes that that is not a strong indicator of pain response to capsaicin in rodents). Neither of those have to do with the consumption of capsaicin, though the second article is pretty interesting! It doesn’t establish a relationship between baseline “rodents” and TRPV1 response though, nor does it make any claims about severity of response or exposure sensitivity (which are not the goals of the paper), but that may be because the only english copy I can find of the article is a fairly abbreviated version of the full chinese text (and I uh… do not read written chinese very well at all, let alone discussions of technical biology).