What Is the Relationship between Neurotransmitters and Pain?

Neurotransmitters are chemicals in the nervous system that help to pass information between neurons. Some neurotransmitters are responsible for the transmission of pain signals, while others help to block pain. Researchers are investigating the relationship between various types of neurotransmitters and pain in hopes of creating new treatments for chronic pain.

Messages are sent through the nervous system by means of electrical and chemical signals. Electrical signals pass through the nerves themselves, but nerves are separated from one another by small gaps, known as synapses, through which the electrical signals cannot pass. At the end of a nerve cell, these signals are converted to chemical signals in the form of neurotransmitters, which pass the message across the synapse to the next nerve cell.

Some of the most important messages sent through the nervous system are messages relating to pain. Pain signals the body that something is wrong and that the person feeling pain should take action to correct it, such as by removing one's hand from a hot stove. The various neurons, neurotransmitters and pain responses work together to prevent unnecessary damage to the body.

When pain becomes unmanageable, however, most people will turn to painkillers. Over-the-counter painkillers, such as acetaminophen or ibuprofen, work by blocking the enzyme known as cyclooxygenase (COX) rather than by directly effecting neurotransmitters. These over-the-counter medicines should not usually be taken over an extended period of time, as they tend to lose efficacy the longer they are taken.

To provide stronger pain relief, many doctors will recommend treatments that exploit the relationship between neurotransmitters and pain. The neurotransmitter serotonin, for instance, is usually associated with mood, as serotonin deficiencies often lead to depression. One of its lesser-known functions, however, is to block excess pain signals. For this reason, antidepressants in the Selective Serotonin Re-uptake Inhibitor (SSRI) class of drugs may also be used to treat chronic pain.

Endorphins are another connection between neurotransmitters and pain. This natural painkiller functions in a way that is closely related to morphine. Endorphins, however, are produced primarily through exercise. A steady regimen of exercise may therefore help manage pain better than many other drugs.