Functions of GABA in the body
GABA, the primary inhibitory neurotransmitter of the body is involved in functions of the brain such as behavior, mood, sleep, and cognition. GABA carries out its effects via receptors known as GABAA and GABAB receptors.
GABAA receptors exert a fast inhibitory effect and function by allowing chloride ions to move into the nerve cells. On the other hand, GABAB receptors have a slow inhibitory effect and act by reducing the entry of calcium ions into the neurons.
Disordered functioning of the GABAergic system has been found in some diseases:
- Epilepsy: Low levels of GABA in the body lead to an imbalance in the excitatory-inhibitory system of the brain. Brain cells have reduced inhibitory signals making them persist in an excitatory state. As a result of this hyperactivity, seizures could occur.
- Sleep disorders: GABA plays a key role in regulating the sleep cycle, hence altered GABA neurotransmission could manifest as insomnia.
- Generalized anxiety: Reduced GABA levels lead to a feeling of anxiousness because of the loss of inhibition on the nerve cells.
- Schizophrenia: Though the exact pathway by which schizophrenia occurs is not fully understood, one of the hypotheses maintains that GABAergic system dysfunction is a likely cause. This hypothesis is supported by the effectiveness of drugs that promote GABA receptor functions in this condition.
- Depression: Reduced levels of GABA neurotransmitters have been reported in patients with depression.
- Alcohol use disorder: Alcohol works on the brain by acting on GABA receptors and enhancing their function. However, prolonged intake of alcohol leads to tolerance and alters the function of GABA receptors, causing dependence.
GABA is also found in other organs of the body, such as the pancreas. Its role in pancreatic function has recently gained a lot of interest. Preliminary studies conducted on animal models have shown that GABA helps pancreatic cells to regenerate.
It also helps in controlling the release of insulin from the beta cells of the pancreas as well as the release of glucagon from the alpha cells. These two hormones, insulin, and glucagon, are essential for glucose metabolism in the body.
Furthermore, GABA has been shown to prevent inflammatory and autoimmune responses that destroy the cells of the pancreas, which are both central events leading to diabetes. When taken orally, GABA decreases glucose levels by improving insulin secretion in patients with diabetes. Its safety for use in humans has also been proven.
Other beneficial effects of GABA in diabetes include reducing insulin resistance, improving glucose tolerance, and preserving the insulin-producing cells of the pancreas. While research is still underway, the use of GABA for the management of diabetes appears favorable.
Some dietary sources of GABA include tomatoes, broccoli, potatoes, and cabbage. GABA is also available as a dietary supplement.
Take home points
- Glutamate and GABA are essential neurotransmitters in the body. Glutamate controls excitatory impulses, while GABA regulates inhibitory impulses.
- Glutamate plays an essential role in the gut-brain axis and can be used to improve gastric motility.
- GABA helps maintain brain functions such as behavior, sleep, and cognition.
- GABA has anti-diabetic properties, namely – regulating insulin secretion, regenerating insulin-secreting cells of the pancreas, and reducing glucose levels.
Al-Kuraishy HM, Hussian NR, Al-Naimi MS, Al-Gareeb AI, Al-Mamorri F, Al-Buhadily AK. The Potential Role of Pancreatic γ-Aminobutyric Acid (GABA) in Diabetes Mellitus: A Critical Reappraisal. Int J Prev Med. 2021 Feb 24;12:19. doi: 10.4103/ijpvm.IJPVM_278_19.
Baj A, Moro E, Bistoletti M, Orlandi V, Crema F, Giaroni C. Glutamatergic Signaling Along The Microbiota-Gut-Brain Axis. Int J Mol Sci. 2019 Mar 25;20(6):1482. doi: 10.3390/ijms20061482.
Liu Y, Weng W, Wang S, Long R, Li H, Li H, Li T, Wu M. Effect of γ-Aminobutyric Acid-Chitosan Nanoparticles on Glucose Homeostasis in Mice. ACS Omega. 2018 Mar 31;3(3):2492-2497. doi: 10.1021/acsomega.7b01988.
Mittal R, Debs LH, Patel AP, Nguyen D, Patel K, O'Connor G, Grati M, Mittal J, Yan D, Eshraghi AA, Deo SK, Daunert S, Liu XZ. Neurotransmitters: The Critical Modulators Regulating Gut-Brain Axis. J Cell Physiol. 2017 Sep;232(9):2359-2372. doi: 10.1002/jcp.25518.
Ochoa-de la Paz LD, Gulias-Canizo R, Ruiz-Leyja ED, Sanchez-Castillo H, Parodi J. The Role of GABA Neurotransmitter In The Human Central Nervous System, Physiology, And Pathophysiology. Revista Mexicana de Neurociencia 2-21;22(2)
Teramoto H, Shimizu T, Yogo H, Nishimiya Y, Hori S, Kosugi T, Nakayama S. Gastric emptying and duodenal motility upon intake of a liquid meal with monosodium glutamate in healthy subjects. Physiol Rep. 2014 Jan 6;2(1):e00187. doi: 10.1002/phy2.187.
Tsurugizawa T, Torii K. Physiological roles of glutamate signaling in gut and brain function. Biol Pharm Bull. 2010;33(11):1796-9. doi: 10.1248/bpb.33.1796.