 Because ethanol and tranquilizers such as barbiturates and benzodiazepines function as positive allosteric modulators at GABAA receptors, the brain, in its desire to equalize an unbalanced chemical system, triggers the abrupt stopping of the production of endogenous GABA.This decrease becomes more and more marked as the addiction becomes stronger and as higher doses are needed to cause intoxication.In addition to having sedative properties, GABA is an immensely important regulatory neurotransmitter that controls the heart rate, blood pressure, and seizure threshold among myriad other important autonomic nervous subsystems.