<b>Löysinpä aiheeseen liittyen ihan mielenkiintoisen keskustelunpätkän:</b>
> >> Is there any evidence that taking GABA orally actually gets GABA
> >> to the brain; that is does it cross the Blood Brain Barrier.
> >> Once in the brain - does the brain respond to it the way it
> >> responds to the Benzodiazepines?
>
> j> no. it's inactive orally. There have been many studies which show
> this
> j> clearly.
>
> Can you reference some of these studies for me? No WWW please. Email,
> gopher, ftp, FidoNet, etc. is OK.
Conventional wisdom is that GABA, an amino acid, like other amino acids,
does not cross
the blood brain barrier. Therefore, it is ?difficult if not impossible
to increase brain
concentrations of GABA by peripheral administration.?*. So to get an
overall
increase in GABA in the brain by consuming oral GABA or even injecting
GABA
IV will not change brain levels of GABA.
*Ref: ?The Biochemical Basis of Neuropharmacology? by Cooper, Bloom and
Roth
p 135 (1991 edition)
However , I found a reference by Cavagnini F et al. (J Clin Endo Metab
51(4):789-92, 1980 Oct)
who discovered that levels of growth hormone were affected by a 5 g oral
dose of GABA.
It is not exactly known how this happens because GABA does not freely
pass into the brain.
They state that because the blood brain barrier is weak in the
hypothalamus, that
this is why GH levels are effected. GH is under hypothalamic control.
There are some regions of the pituitary-hypothalamus where
the BBB is absent because neurosecretary hormones (large proteins) need
to
be passed into circulation.
So here we see a localized effect of GABA on the hypothalamus. They
don't claim
any passage into the brain.
The following paper was also discovered:
?The Elevation of cerebral levels of nonessential amino acids by
administration
of large doses? by Toth and Lajtha (Neurochemical Research
6(12):1309-17,1981 Dec)
In a nutshell: animals were force-fed intragastrically taurine, aspartic
acid, glutamic acid,
glycine and GABA. Which resulted in a great increase in plasma levels
which in turn caused
significant increases brain levels. They said that ?even slowly
penetrating amino acid levels
can be increased in brain after parenteral administration of large
doses?.\
I did not read this study since it is a totally artificial situation.
The amount
of GABA consumed by a person to equal these force-fed quantities would
be
likely be astronomical.
To annswer the original question, No,
In a normal healthy person, consuming GABA orally will not result in a
benzodiazepine-like
effect.
--
John T. Robicheau JTRst4+@Pitt.edu
University of Pittsburgh School of Pharmacy
Registered Pharmacist (VA Health System) PhD Candidate
