What Are Neurotransmitters?

Many mental illnesses and neurological disorders are linked to problems with neurotransmitters.

Neurotransmitters are a special type of chemical compound that occurs naturally in your body.

Their role is to carry impulses from one part of the brain to another, and from the brain to the rest of the body.

Neurotransmitters work by sending chemical signals between nerve cells called neurons, which are found throughout the brain, spinal cord, and the rest of the nervous system.

Dozens of different neurotransmitters are at work in your nervous system.

Some important neurotransmitters include:

• Glutamate
• Serotonin
• Dopamine
• Acetylcholine
• GABA
• Histamine

There are two main types of neurotransmitters: excitatory neurotransmitters and inhibitory neurotransmitters. Excitatory neurotransmitters stimulate nerve activity, while inhibitory neurotransmitters decrease or dampen nerve activity.

Mental illnesses, such as depression, may occur when there are imbalances of certain neurotransmitters.

Neurological disorders including Alzheimer's disease, Parkinson's disease, and epilepsy are also associated with changes in the way the brain produces or uses neurotransmitters.

Neurotransmitter Receptors

Many of the medications used to treat mental illness and neurological disorders target neurotransmitters in the brain, or the neurotransmitter receptors on cells that receive the chemical signals.

Drugs that bind to neurotransmitter receptors, mimicking the activity of a neurotransmitter chemical binding to the receptor, are called agonists.

Antagonist drugs block a chemical response at a neurotransmitter receptor.

Opiate painkillers, including morphine and codeine, are examples of agonist drugs that bind to and activate neurotransmitter receptors, producing feelings of pain relief.

Medications used to treat schizophrenia and other mental disorders, including clozapine (Clozaril) and haloperidol (Haldol), are antagonists that block dopamine receptors in the brain.

Neurotransmitters and Addiction

Some street drugs, including cocaine, methamphetamine, heroin, marijuana, nicotine, alcohol, and prescription painkillers, can alter a person's behavior by interfering with neurotransmitters and the normal communication between brain cells.

Drug dependence and addiction can be caused by a drug's cumulative impact on neurotransmission — the brain's chemical signaling system.

Over time, with repeated drug use, some drugs can actually change the structure of the brain and its chemical makeup.