THE BRAIN FROM TOP TO BOTTOM

Fear, Anxiety and Anguish

ANXIETY NEUROTRANSMITTERS

GABA is a chemical messenger that is widely distributed in the brain. GABA’s natural function is to reduce the activity of the neurons to which it binds. Some researchers believe that one of the purposes that GABA serves is to control the fear or anxiety experienced when neurons are overexcited.

This hypothesis is supported by the fact that the medications used to alleviate anxiety, such as Valium and Librium, bind to the same neuronal receptors as GABA.

The effect of these medications, which are classified as benzodiazepines, is to enhance the natural effect of GABA. In other words, they help GABA to reduce neural activity even further. This is why these molecules help to calm us down.

But GABA is not the only chemical messenger involved in anxiety.

GABA RECEPTORS

GABA receptors are probably the most common kind in the mammalian nervous system. It is estimated that close to 40% of the synapses in the human brain work with GABA and therefore have GABA receptors.

GABA receptors are channel receptors. This means that when GABA binds to them, they change shape slightly to allow ions to pass through their central channel. This channel mainly allows negatively charged chloride neurons to enter the neuron, thus reducing its excitability.

Because of this property of the GABA channel receptor, GABA is classified as an inhibitory neurotransmitter, as opposed to excitatory neurotransmitters, such as glutamate, which augment the nerve impulses in the neuron.

GABA is the natural “key” to the GABA channel receptor’s “lock”. But GABA is not the only molecule that can modify this channel receptor’s opening. Other molecules can also affect it, such as the benzodiazepine medications used to treat anxiety. By binding to this receptor at different sites from GABA, the benzodiazepines help to reduce the transmission of the neural message.