Substances such as substance P, 5-hydroxytryptamine, vasoactive intestinal peptide, somatostatin, and prostaglandins, as well as acetylcholine and norepinephrine function as:

Recently a great deal of information has been reported regarding the types of potential neurotransmitters that are present in the nerves of the dental pulp. Substances such as substance P, 5-hydroxytryptamine, vasoactive intestinal peptide, somatostatin, and prostaglandins, as well as acetyl-choline and norepinephrine have been found throughout the pulp. The majority of these putative transmitters have been shown to affect vascular tone and subsequently modify the excitability of the nerve endings