insulin and the brain

[pat doyle]

In article <422nn3$nqi at whitbeck.ncl.ac.uk>, erasmus harland
<p.s.e.harland at ncl.ac.uk> wrote:

> thanks for your note/ I am working on insulin resistance. Presumably 
> glucose within the csf has to get into neurones, is there a specific 
> glucose transport protein for neurones, or is it the same mechanism for 
> entering muscles cells.  My hypothesis is than insulin resistance by 
> decreasing uptake into muscle, protects the brain from hypoglyaemia in 
> small for dates babies, who, when they are adults have  higher risk of 
> insulin resistance, hypertension and mortality from coronary heart 
> disease - the Barker hypothesis - or the thrifty genotype postulated by 
> Neel,

Brain has several specific types of glucose transporter :
GLUT 1 45 KDa astrocytes
GLUT 1 55 KDa capillaries and bbb     1 and 3 glucose transport 
GLUT 3 46 KDa neurones
GLUT 5 ? KDa  microglia - fructose transport
 

GLUT 1 and 3 are supposedly insulin insensitive.Penicaud et al have
localized GLUT 2 in hypothalamus - i.e. glucose sensor as in liver.We have
immunohistochemistry of GLUT 4  in hypothalamus (insulin responsive as in
muscle)....Good luck Pat Doyle.