It has been traditionally thought that exogenous GABA (i.e., taken as a supplement) does not cross the blood–brain barrier, but data obtained from more recent research (2010s) in rats describes the notion as being unclear.

It was thought that a developmental switch in the molecular machinery controlling the concentration of chloride inside the cell changes the functional role of GABA between neonatal and adult stages.

GABAergic interneurons mature faster in the hippocampus and the GABA machinery appears earlier than glutamatergic transmission.

[15] GABA regulates the proliferation of neural progenitor cells,[16][17] the migration[18] and differentiation[19][20] the elongation of neurites[21] and the formation of synapses.

GABA can influence the development of neural progenitor cells via brain-derived neurotrophic factor (BDNF) expression.

[23] GABA activates the GABAA receptor, causing cell cycle arrest in the S-phase, limiting growth.

[24] Besides the nervous system, GABA is also produced at relatively high levels in the insulin-producing beta cells (β-cells) of the pancreas.

[30] Alongside GABAergic mechanisms, GABA has also been detected in other peripheral tissues including intestines, stomach, fallopian tubes, uterus, ovaries, testicles, kidneys, urinary bladder, the lungs and liver, albeit at much lower levels than in neurons or β-cells.

In the gas phase, a highly folded conformation is strongly favored due to the electrostatic attraction between the two functional groups.

[43] In 1950, Washington University School of Medicine researchers Eugene Roberts and Sam Frankel used newly-developed techniques of chromatography to analyze protein-free extracts of mammalian brain and discovered that GABA is produced from the glutamic acid and accumulates in the mammalian central nervous system.

[56] At least one study suggests that orally administered GABA increases the amount of human growth hormone (HGH).

[57] 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.

[56] Consequently, considering the potential biphasic effects of GABA on growth hormone production, as well as other safety concerns, its usage is not recommended during pregnancy and lactation.

[59] It is thus suspected that GABA is involved in the synthesis of melatonin and thus might exert regulatory effects on sleep and reproductive functions.

[nb 1] GABAergic pro-drugs include chloral hydrate, which is metabolised to trichloroethanol,[75] which then acts via the GABAA receptor.

[76] The plant kava contains GABAergic compounds, including kavain, dihydrokavain, methysticin, dihydromethysticin and yangonin.