Prozac and Neurogenisis

John H. john at faraway.com.au
Mon Sep 8 03:03:21 EST 2003



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"Matthew Kirkcaldie" <Matthew.Kirkcaldie at newcastle.edu.au> wrote in message
news:Matthew.Kirkcaldie-ACF06E.09025808092003 at seagoon.newcastle.edu.au...
> In article <3f598c5c at dnews.tpgi.com.au>,
>  "John H." <john at faraway.com.au> wrote:
>
> > As to ssris and neurogenesis, my spin on that is as serotonin levels
rise
> > the HPA axis is modified reducing cortisol levels, the dentate gyrus is
very
> > high in GC receptors and neural progenitor cells v. sensitive to
> > glucocorticoids. Thus the delay in ssri efficacy may relate to this slow
> > turning down of excessive cortisol production, which is one of the most
> > frequently reported aspects of depression.
>
> Interesting call - after all, we do know that stress decreases
> neurogenesis, and I recently saw a talk describing glucocorticoid
> mechanisms in hippocampus which were of possible relevance to your idea
> there.
>
> I still think there is a strong argument to be made in favour of the DG
> turnover contributing to behavioural integration, though - have a look
> at the Kempermann review from last year (if you can stomach the irksome
> computer analogies).

Yes, I think that is worth considering, the DG probably plays some part
here. I vaguely recall how progenitor cells did migrate to form new networks
in CA1 or 3, though how this observation was determined is beyond this
meagre mind (no lab experience). I also recall some studies from last year
demonstrating how cells forming in the DG or olfactory bulb actually
migrated well into the neocortex, and recently some other studies claiming
that in mice cell replacement can occur in the substantia nigra (or equiv,
my anatomy is bad ... ). It really is quite amazing to contemplate such a
migration in a mature brain, its dazzling enough in embryonic stage.

The other issue to consider is that the hippo is amongst the most vulnerable
of CNS regions: depression, ALZ, stress. V. high concentration of GC
receptors. Makes evolutionary sense at least.


>       Cheers,
>
>          Matthew.





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