Question

What are the neurotransmitters of first-order pain neurons?

Answer 1

In the pain pathway there are 3 main orders of neurons which are responsible for carrying action potentials signalling pain.

First order neurons are defined as pseudounipolar neurons which have cells bodies within the dorsal root ganglion.

The main neurotransmitters of first oder pain are : Glutamate and Substance P

Glutamate transmits pain by binding to 5-subunit ligand-gated ion channels located on nociceptive neurons on myelinated pain afferents which belongs to the class of afferent axons reffered to as A-delta that are responsible for transmitting to the dorsal horn of the spinal cord.

Substance p transmits pain by secretion from nerves and inflammatory cells, and they acts by binding to neurokinin-1 receptors which are located on the nociceptive neurons on unmyelinated primary afferents, known as C fibers, to the dorsal horn of the spinal cord.