6 replies to this topic

[ikaros]

A lot of stores sell so called Gaba in a powder form. As far as I have understood Gaba by itself doesn't cross the blood-brain barrier. Are those products bogus?

[graatch]

kek

http://www.mindandmu...php/t22453.html

trouble
Mar 6 2006, 08:35 PM
It's not so much that GABA doesn't cross the BBB into the brain, but that it is one of the key gatekeepers, along with taurine and alanine, in control of who crosses and in maintenance of brain hydration and ions.

Homocysteine in microvascular endothelial cell barrier permeability. Tyagi SC, Lominadze D, Roberts AM. Cell Biochem Biophys. 43(1):37-44 (2005).

Redox stress activates the endothelium and upregulates matrix metalloproteinases (MMPs), which degrade the matrix and lead to blood-endothelial barrier leakage. Interestingly, elevated levels of plasma homocysteine (Hcy) are associated with vascular dementia, seizure, stroke, and Alzheimer disease. Hcy competes with the gamma-aminobutyric acid (GABA)-A/B receptors and behave like an excitatory neurotransmitter. GABA stimulates the inhibitory neurotransmitter GABA-A/B receptor and decreases arterial blood pressure. However, the neural mechanisms of microvascular remodeling in hyperhomocysteinemia are unclear. This review addresses the idea that Hcy induces microvascular permeability by attenuating the GABA-A/B receptors and increasing redox stress, which activates a disintegrin and metalloproteinase that suppresses tissue inhibitors of metalloproteinase. This process causes disruption of the matrix in the blood-brain barrier. Understanding the mechanism of Hcy-mediated changes in permeability of the blood-brain barrier and extracellular matrix that can alter the neuronal environment in cerebral-vascular dementia is of great importance in developing treatments for this disease.



Efflux of a suppressive neurotransmitter, GABA, across the blood-brain barrier. Kakee A, Takanaga H, Terasaki T, Naito M, Tsuruo T, Sugiyama Y.
J Neurochem. 2001 Oct;79(1):110-8.

Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan.

In this study, GABA efflux transport from brain to blood was estimated by using the brain efflux index (BEI) method. [3H]GABA microinjected into parietal cortex area 2 (Par2) of the rat brain was eliminated from the brain with an apparent elimination half-life of 16.9 min. The blood-brain barrier (BBB) efflux clearance of [3H]GABA was at least 0.153 mL/min/g brain, which was calculated from the elimination rate constant (7.14 x 10(-2) x min(-1)) and the distribution volume in the brain (2.14 mL/g brain). Direct comparison of the apparent BBB influx clearance [3H]GABA (9.29 microL/min/g brain) and the apparent efflux clearance (153 microL/min/g brain) indicated that the efflux clearance was at least 16-fold greater than the influx clearance. In order to reduce the effect of metabolism in the neuronal cells following intracerebral microinjection, we determined the apparent efflux of [3H]GABA in the presence of nipecotic acid, a GABA transport inhibitor in parenchymal cells, using the BEI method. Under such conditions, the elimination of [3H]GABA across the BBB showed saturation and inhibition by probenecid in the presence of nipecotic acid. Furthermore, the uptake of [3H]GABA by MBEC4 cells was inhibited by GABA, taurine, beta-alanine and nipecotic acid in a concentration-dependent manner. It is likely that GABA inhibits the first step in the abluminal membrane uptake by brain endothelial cells, and that probenecid selectively inhibits the luminal membrane efflux transport process from the brain capillary endothelial cells based on the in vivo and in vitro evidence. The BBB acts as the efflux pump for GABA to reduce the brain interstitial fluid concentration.

[graatch]

I definitely feel a nice ... cooling-down when I take GABA at 500-2000mg in anxious or burnt-out states. 3-4 times a day. Exceeding the dosages makes me flushed.

Paradoxically to what your regular Braverman junky might expect, it makes it more difficult to sleep IME and I don't take it after 6pm.

[mbrutis]

I definitely feel a nice ... cooling-down when I take GABA at 500-2000mg in anxious or burnt-out states.  3-4 times a day.  Exceeding the dosages makes me flushed.

Paradoxically to what your regular Braverman junky might expect, it makes it more difficult to sleep IME and I don't take it after 6pm.

Holy cow, makes me sleep like a baby. I take just enough to get a good flush going, which is short lasting, then the race to find a horizontal surface begins.

Also notice a difference when I don't take it before bed on a workout day when I push a large muscle group like legs. Marked increase in soreness the next morning if I forget my GABA & Magnesium.

[mike250]

I haven't felt anything from it really. I prefer L-theanine

[mbrutis]

I haven't felt anything from it really. I prefer L-theanine

Love 'em both. Too close to bedtime though, and theanine keeps me thinking a bit too much.

[mike250]

where do you get your L-theanine from? I bought capsules from natural factors but it gave me a weird reaction and then recently bought some powder off unique nutrition. L-theanine + ALCAR is an awesome combo.