This is the 2007 version. Click here for the 2017 chapter 02 table of contents.


GABA (Gamma-aminobutyric acid) was the first new transmitter to be discovered after the three "classic" transmitters (norepinephrine, acetylcholine, and serotonin). It is one of the most frequently occurring transmitters in the central nervous system. Generally it has an inhibitory function. Sedative-hypnotic drugs like barbiturates act by stimulating release of GABA-like substances.

What is the usual effect of GABA?

Valium and the class of tranquilizers it represents, benzodiazepines, also act on the GABA-related transmitter systems. The benzodiazepines and the barbiturates are quite different in their structure, clinical effects, and mode of action...but they both act to reduce anxiety, and they both do it by boosting levels of GABA.

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