Photo;By Danny Hope from Brighton & Hove, UK (My Right Eye Uploaded by Pieter Kuiper)
[CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
Thus the twin toxic hypers of modern excess sugar consumption,
hyperglycaemia and hyperinsulinism, separately and synergistically
suppress and inhibit glucose transport into the brain via suppression
of the cerebral glucose pump – the
glutamate/glutamine cycle, known
as the iPump. Neither fats nor proteins play any part in this pathological process – indeed fats play
a positive role in cerebral glucose
metabolism via leptin, adiponectin
and fibroblast growth factor 9 (FGF
9).
34
The Hungry Retina
and Dementia
The human retina consumes even
greater energy on a cell for cell
basis than does the human brain,
which is why it is the most vulnerable tissue in any decrement in
energy supply. We know this from
any attack of hypoglycaemia; the
retina cells are the first cerebral
energy cells to respond – vision
is blurred and stars appear in the
visual field. Modern humans are
subject not to chronic energy deficits but to chronic energy overload in the circulation, and here
again we observe that the first
tissue to register the suppression of the retinal glucose pump are the retinal
glial cells; glutamate, the
cerebral (retinal) hunger
signal, is not converted to
glutamine, and glutamate
is the most excitotoxic
amino acid in the brain;
excess accumulation of toxic
glutamate and damage to the
retina is expressed many years
before visual loss manifests.