F. Frank LeFever <flefever at ix.netcom.com> wrote in article
<5dbkeg$i1g at dfw-ixnews11.ix.netcom.com>...
> A few years ago, Don Stein reported that intracerebral administratioon
> of NGF improved pperformance of rats with cerebral lesions, but not
> normal rats; indeed, may have impaired performance of normal rats.
This has been shown in several studies since then. It seems that while NGF
improves performance in impaired animals (e.g. aged rats, rates with
cerebral lesions etc.), it has the opposite effects when administered to
young or intact animals.
NGF is vital for the development and survival of basal forebrain
cholinergic neurons. When administered intraventricularly or
intracerebrally (or even systematically, as reported by Backman et al.
(1996) J. Neurosci. 16, 5437) it prevents cholinergic neuron loss; it also
induces increases in the complexity and vastness of the dendritic fields of
these neurons. NGF administration to young adult animals may trigger
sprouting of intact cholinergic fibers, which leads to undesirable
modification of basal forebrain cholinergic system function and results in
behavioral impairments. For example see:
Crutcher KA, Saffran BN (1990) Soc Neurosci Abstr 16:993
Saffran, Crutcher (1990) Brain Res 525:11.
Hope this helps.
Aristotle University Faculty of Medicine