Dear Sheldon and all,
I highly doubt that anyone can tell you the neuroendocrine system plays little role in human aging. Studies that prevented aging (by preventing the continuous nuclear presence of NF-kB) in the hypothalamus actually increased lifespan by some twenty-odd percent. That brain region has a major high level body clock with subordinate tissue clocks in train to it (the superchiasmatic nucleus). Now the effect of this interference with normal aging, the effect of this hypothalamic aging on other tissue resulted at least in part from the decreased secretion of gonandotrophin releasing hormone. When that ‘hormone’ was provided to aging animals, the lifespan increased by twenty-something percent. Preventing NF-kB entry into the nucleus or provision of neuroendocrine signaling molecules delayed tissue aging, but I guess didn’t eliminate it as the animals eventually died. Similar experiments with mouse skin – again preventing the continuous NF-kB activation (nuclear translocation) required for aging – brought the skin back to youthful condition.) Now can we say for certainty the same wouldn’t apply to humans? ( I don’t think so – and it’s not hard, I think, to devise experiments – even on humans). Anyway I don’t believe that aging occurs an the level of the organs even the brain, or at the level of the cell – I think we see that these levels interact with each other. We see it in this instance – cellular changes allowing the NF-kB transcription factor into the nucleus, producing changes in hormone levels producing changes in tissues with must ultimately be resolved as changes to cells.