What Is the GABA Neurotransmitter?

-aminobutyric acid (CAS number: 1492-24-6) alias 4-aminobutyric acid (GABA) has a relative molecular weight of 103.1, and is a four-carbon, non-protein amino acid. It is widespread in microorganisms. ^[1]

Although the European Food Safety Authority (EFSA) allows the addition of GABA to foods, the upper limit of the dietary intake of GABA is 550mg / d, but its main functional characteristics need to be confirmed by rigorous population test results. US Food and Drug Administration

There are many discoveries in GABA automatic plants and microorganisms. Among them, it was first found in potato tubers in 1949, and found in the mammalian central system in 1950. It is also considered to be mammals, insects or some Neuroinhibitors in the parasitic worm nervous system have an important effect on the degree of excitability of neurons. ^[2]

In 1993, some scholars successfully developed GABA through chemical synthesis for the first time. Since then related research has become increasingly abundant. GABA can be developed as a drug or health food with significant pharmacological effects, and has a very promising future. In order to obtain more GABA, researchers have started various attempts and achieved many results. ^[2]

There are two GABA synthesis and transformation pathways in plants: one is the synthesis of GABA by glutamic acid via glutamic acid decarboxylase (GAD), which is called GABA shunt; the other is GABA shunt; One is the conversion of polyamine degradation products to form GABA, known as the polyamine degradation pathway (see the figure on the right for details) ^[1]

In microorganisms, GABA metabolism is completed through the GABA branch. Using the higher GAD activity in the microorganism, Glu is decarboxylated to form GABA. Then under the action of GABA-T and SSADH, GABA enters the downstream decomposition process to generate succinic semialdehyde , Succinic acid participates in the physiological metabolism of microorganisms. The microbial enrichment of GABA is achieved by optimizing the culture medium and improving the strain to make it have higher GAD activity, increase the GABA synthesis rate, and reduce the decomposition rate. A large number of studies have proved that GAD exists in prokaryotic to eukaryotic microorganisms. In addition, the use of GAD in microorganisms to form GABA is not limited by resources, environment and space, and has significant advantages compared with other methods. ^[1]

GABA has special medicinal value, and its treatment of epilepsy has been one of the hot spots in recent years. In several years of research on anti-neuropathic pain, most synthetic GABA triazole derivatives have been found to have antiepileptic, paroxysmal, and antihyperalgesic effects. The GAD activity of patients with epilepsy and non-epileptic patients was found to be lower than that of non-epileptic patients. Later studies also found that GABA release and GABA storage mechanism are closely related to epilepsy. And the weakening of GABA inhibition can lead to seizures. Drugs that increase GABA metabolism have shown initial success in treating epilepsy. At present, the cause of epilepsy is thought to be that the balance between nerve self-excitation and inhibition is disrupted, and GABA plays an important role in this. The subpopulation of GAD neurons in patients with epilepsy is susceptible to damage during the onset, leading to a decrease in GABAergic neurons, while other neurons will upregulate GAD expression to maintain this balance. ^[7]

GABA has long been thought to be involved in a variety of plant stress and defense systems. GABA increases with the stimulation of plants, and is considered to be an effective mechanism in plants in response to various external changes, internal stimuli, and ionic environment factors such as pH, temperature, and external natural enemy stimuli. GABA can also regulate the internal environment of plants such as antioxidant, ripening, fresh-keeping plants and so on. In recent years, GABA has also been found in plants as a signaling molecule to transmit expanded information in plants. GABA has been found in soybean, Arabidopsis, jasmine, strawberry and other plants. Low concentration of GABA helps plant growth and development, and high concentration will have the opposite effect. ^[7]

Under the continuous research of GABA, researchers have learned that GABA has many pharmacological activities. Therefore, research on the preparation and extraction of GABA has been paid more and more attention by scientists at home and abroad, so that the development of GABA in the food field has also become an important direction. ^[2] Especially in Japan, because of its successful development of germinated brown rice rich in GABA, other related GABA-containing products have been vigorously developed, and have been widely praised by people. GABA is now widely used in food, medicine, health products and seasonings, and can be adapted to different ages and population structures. ^[2]