Yeah I have used drugs that act on GABA briefly. I don’t think GABA is close at all in efficacy to Serotonin signaling in decreasing chronic high norepinephrine.

http://forum.mesomorphosis.com/mens-health-forum/adrenal-fatigue-getting-worse-134249714.html

“Increasing serotonin is useful since it quickly reduces the perception of stress. Blocking stress is the most predictable effect of an SSRI. This results in a reduction in anxiety, a reduction of overall stress signals (e.g. norepinephrine, ACTH) to the adrenal glands – giving the adrenal glands some breathing room to rest and recover. Over time, as the adrenal glands recover from fatigue, their improved output can reduce norepinephrine levels, helping restore dopamine production, and reduce depressive and anxiety symptoms. Brain function changes to a more non-depressed state. The reduction in norepinephrine and increase in serotonin helps reduce premature ejaculation – which tends to be caused by high norepinephrine levels (since a burst of norepinephrine triggers orgasm, high norepinephrine levels can cause one to be trigger happy so to speak).

Excessively increasing serotonin levels, however, will reduce dopamine production from dopamine neurons. This will further increase norepinephrine production from norepinephrine neurons – since a tract from the dopamine neurons helps control norepinephrine production. The reduction of dopamine and increase in norepinephrine creates a side effect called akathisia. Symptoms include agitation, restlessness, insomnia, anxiety, tension, irritability, fidgetiness, etc. At its worse, it leads to a feeling of wanting to jump out of one’s skin – leading sometimes to impulsive behaviors such as suicide. The increase in suicide risk from antidepressants lead to the FDA requiring warnings about this. Of course, they could not explain it as I have. I usually tell patients to reduce the dose themselves when they get akathisia – to prevent problems like suicide from even occurring.

In any case, serotoninergic medications are useful in the toolkit to help reduce adrenal fatigue. The key is the dose – a balance needs to be made. But they are also only one component of many that may be necessary to get as complete a treatment as one can for adrenal fatigue. And there are some people who cannot tolerate them at all – e.g. people with a family history of Parkinson’s Disease – where they may have lower than usual levels of dopamine production to begin with.”