Chapter 22, End of Chapter, Review Questions, Exercise 1

Drugs that reduce anxiety are known as anxiolytic drugs. These drugs alter the synaptic transmission in the brain. One such example is a class of drugs called benzodiazepines. These drugs are specifically depressants of the nervous system in nature similar to that of alcohol, heroin, and cannabis. It is generally used as a sedative for inducing sleep and treating anxiety disorders. 

GABA_A- gated channels increase membrane permeability to Cl^- ion. Whenever the neurotransmitter binds to its channel, it causes inward movement of chloride ions, thereby causing hyperpolarization of the postsynaptic cell since the chloride equilibrium potential is negative. It changes the membrane potential away from the threshold, required for an action potential to be generated. Therefore gated ion channels have an inhibitory effect on the action potential, producing a transient hyperpolarization of the postsynaptic membrane called the inhibitory postsynaptic potential (IPSP).

There must be a balance in the excitation and inhibition that occurs in the brain. Too much inhibition results in coma, and less amount of inhibition results in epilepsy or seizures. 

Benzodiazepines, such as diazepam (valium) is well known for treatment of anxiety disorders. In general, all the drugs that can stimulate the activity of GABA_A receptors that have an agonistic role are anxiolytic including ethanol which is an  active ingredient in alcoholic drinks. These drugs suppress the activity of the brain circuits involved in induction of fear or anxiety. Therefore, these treatments are needed to restore the normal functioning of these pathways.