Histamine

Histamine is an excitatory neurotransmitter involved in the sleep/wake cycle and inflammatory response. Depending on the receptor histamine activates a wide array of biological actions can occur. For instance, one receptor helps regulate the sleep/wake cycle whereas another receptor helps regulates norepinephrine, serotonin, and acetylcholine release. There are also other receptors that may be activated to induce inflammatory response, which is commonly associated with the exposure to an allergen.