insulin and the brain

Paul L Pearson rambis at
Fri Aug 25 10:45:27 EST 1995

In <41ifg8$n0k at> sfm at (Stephen Matheson) writes:

>From article <41iaji$ccl at>,
>by Matt Jones <jonesmat at>:
>> In article <41hpov$mqk at> erasmus harland,
>> p.s.e.harland at writes:
>>>I am interested in brain metabolism, how does insulin function in 

>> My understanding was that insulin doesn't cross the blood/brain
>> barrier, and so doesn't have direct effects on neurons, but rather
>> indirect effects through altering the glucose levels in the blood
>> the goes to the brain. Is this completely wrong?

>I estimate it to be about 50% wrong :-).  While I'm pretty sure
>that insulin does not cross the BBB, that does *not* mean that
>it doesn't have direct effects on neurons.  There are 2 ways
>that insulin could have direct neuronal effects without
>breaching the BBB: 1) by affecting neurons that are outside
>the BBB; 2) via cellular synthesis and release within the
>brain.  The first is most definitely the case for various
>hypothalamic neurons.  The second is hinted at by reports of
>expression of insulin mRNA by CNS neurons and by demonstrations
>of mRNA expression and insulin secretion by some cultured
>Steve Matheson                      sfm at
>"...lips that speak knowledge are a rare jewel."  --Proverbs

I did a good chunk of my prelim. proposal on insulin in the brain.
Check out the review by Schwartz et al., Insulin in the Brain: A
Hormonal regulator of energy balance, Endocrine Reviews 13:387-414
(1992).  If this doesn't answer a lot of your questions, it should refer
you to the papers that do.

Insulin has a dramatic effect on the regulation of neuropeptide Y, and
thus food intake, in the arcuate nucleus.  I believe the Zucker fatty
rat is insulin insensitive in the arcuate, thus overexpressing NPY
resulting in carbohydrate hyperphagia.  This may also be the case for
the obese mouse model, if I remember correctly.


Paul L. "Pro" Pearson
President, Kurt Rambis Fan Club (unofficial)
Ames, IA Chapter

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