Dynamic interactions between the nervous system, hormones and the immune system are normally on-going but in diabetes the balance is disturbed. The two studies published in EBioMedicine highlight the importance of the neurotransmitter gamma-aminobutyric acid (GABA) in both Type 1 and Type 2 diabetes.
GABA is synthesized by an enzyme called GAD from the amino acid glutamate in nerve cells but also, importantly, in the insulin-producing beta cells in pancreatic islets. GAD has two forms, GAD65 and GAD67. In type 1 diabetes, beta cells are destroyed while type 2 diabetes is associated with impaired beta cell function and insulin resistance.
Patients with type 1 diabetes often have antibodies to GAD65. However, there has been no strong link between GABA and type 2 diabetes until recently when it was shown that GABA is important for maintaining and potentially also in the making of new beta cells.
The two current studies, now published in EBioMedicine, reinforce the image of GABA's importance, for both types of diabetes. The scientists used ion channels that GABA opens, the GABAA receptors, as a biological sensor for GABA, and were able to determine the effective, physiological GABA concentration levels in human pancreatic islets. They also showed that these ion channels became more sensitive to GABA in type 2 diabetes and that GABA helps regulate insulin secretion (Article 1).
Authors show that 100–1000 nM GABA elicit the maximal opening frequency of the single-channels. In saturating GABA, the channels desensitized and stopped working.
GABA modulated insulin exocytosis and glucose-stimulated insulin secretion. GABAA receptor currents were enhanced by the benzodiazepine diazepam, the anesthetic propofol and the incretin glucagon-like peptide-1 (GLP-1) but not affected by the hypnotic zolpidem. In type 2 diabetes (T2D) islets, single-channel analysis revealed higher GABA affinity of the receptors.
The scientists then isolated immune cells from human blood and studied the effects GABA had on these cells. They show that GABA inhibited the cells and reduced the secretion of a large number of inflammatory molecules (Article 2).
The anti-inflammatory effect of GABA may be vital in the pancreatic islets since as long as GABA is present, toxic white blood cells can be inhibited, thus increasing the survival of the insulin-secreting beta cells. When the beta cells decrease in number and disappear from the islets as happens in Type 1 diabetes, then GABA consequently is also decreased and, thereby, the GABA protective shielding of the beta cells. When inflammatory molecules increase in strength, it may weaken and even kill the remaining beta cells.
In ongoing studies, the scientists now focus on clarifying the GABA signaling mechanisms in the immune cells and in the human beta cells. They will also study how existing drugs can increase, decrease or mimic the effects of GABA, says the author.
http://www.uu.se/nyheter-press/nyheter/artikel/?id=10442&area=4,10,16,40&typ=artikel&lang=sv
http://www.ebiomedicine.com/article/S2352-3964(18)30098-7/fulltext
http://www.ebiomedicine.com/article/S2352-3964(18)30103-8/fulltext
GABA in pancreatic islets!
- 1,955 views
- Added
Edited
Latest News
A new brain circuit in mice…
By newseditor
Posted 08 May
Mechanism of choline entry…
By newseditor
Posted 07 May
Link between UTI and breast…
By newseditor
Posted 07 May
Sleep resets brain connections
By newseditor
Posted 07 May
Interplay of various enzyme…
By newseditor
Posted 07 May
Other Top Stories
An intestinal zinc sensor in flies regulates food intake and develo…
Read more
Enzyme targeted by TB antibiotic later stops the drug destroying it
Read more
Antibiotic daptomycin intercepts building blocks of the bacterial e…
Read more
Current oral polio vaccine causes disease outbreak!
Read more
Digestive symptoms are prominent among COVID-19 patients
Read more
Protocols
Single-cell adhesive profil…
By newseditor
Posted 07 May
Parasympathetic neurons der…
By newseditor
Posted 07 May
Non-invasive measurements o…
By newseditor
Posted 05 May
A validation strategy to as…
By newseditor
Posted 04 May
Generation of rat forebrain…
By newseditor
Posted 03 May
Publications
Synaptotagmin-11 facilitate…
By newseditor
Posted 08 May
Astrocytic Slc4a4 regulates…
By newseditor
Posted 08 May
Diabetic retinopathy is a c…
By newseditor
Posted 08 May
A body-brain circuit that r…
By newseditor
Posted 07 May
Host response during unreso…
By newseditor
Posted 07 May
Presentations
Hydrogels in Drug Delivery
By newseditor
Posted 12 Apr
Lipids
By newseditor
Posted 31 Dec
Cell biology of carbohydrat…
By newseditor
Posted 29 Nov
RNA interference (RNAi)
By newseditor
Posted 23 Oct
RNA structure and functions
By newseditor
Posted 19 Oct
Posters
A chemical biology/modular…
By newseditor
Posted 22 Aug
Single-molecule covalent ma…
By newseditor
Posted 04 Jul
ASCO-2020-HEALTH SERVICES R…
By newseditor
Posted 23 Mar
ASCO-2020-HEAD AND NECK CANCER
By newseditor
Posted 23 Mar
ASCO-2020-GENITOURINARY CAN…
By newseditor
Posted 23 Mar