<P> GABA transaminase enzyme catalyzes the conversion of 4 - aminobutanoic acid (GABA) and 2 - oxoglutarate (α - ketoglutarate) into succinic semialdehyde and glutamate . Succinic semialdehyde is then oxidized into succinic acid by succinic semialdehyde dehydrogenase and as such enters the citric acid cycle as a usable source of energy . </P> <P> Drugs that act as allosteric modulators of GABA receptors (known as GABA analogues or GABAergic drugs), or increase the available amount of GABA, typically have relaxing, anti-anxiety, and anti-convulsive effects . Many of the substances below are known to cause anterograde amnesia and retrograde amnesia . </P> <P> In general, GABA does not cross the blood--brain barrier, although certain areas of the brain that have no effective blood--brain barrier, such as the periventricular nucleus, can be reached by drugs such as systemically injected GABA . At least one study suggests that orally administered GABA increases the amount of human growth hormone (HGH). GABA directly injected to the brain has been reported to have both stimulatory and inhibitory effects on the production of growth hormone, depending on the physiology of the individual . Certain pro-drugs of GABA (ex . picamilon) have been developed to permeate the blood--brain barrier, then separate into GABA and the carrier molecule once inside the brain . This allows for a direct increase of GABA levels throughout all areas of the brain, in a manner following the distribution pattern of the pro-drug prior to metabolism . </P> <P> GABA enhanced the catabolism of serotonin into N - acetylserotonin (the precursor of melatonin) in rats . It is thus suspected that GABA is involved in the synthesis of melatonin and thus might exert regulatory effects on sleep and reproductive functions. (1) </P>

A type of drug that works by enhancing the action of the neurotransmitter gaba