Histamine is a compound that affects immune response and physiological function of the digestive tract, and also acts as a neurotransmitter.

What are some functions of Histamine?

Histamine helps control the sleep-wake cycle as well as energy and motivation.

The sleep-wake cycle and other areas:

Histamine is a 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 an inflammatory response, which is commonly associated with the exposure to an allergen.

…within the brain:

Interestingly, histamine containing neurons have been found to have a pacemaker function within the brain. The firing rates of these neurons correlate positively with brain activity levels and display distinct day-night rhythms. Within the posterior region of the hypothalamus, there are a large number of neurons that synthesize and utilize histamine. These neurons provide the stimulation that maintains or modulates activity in many other regions of the brain.

Storage and binding:

Histamine, like the other biogenic amines (serotonin, dopamine, norepinephrine, epinephrine, and PEA) is stored in presynaptic vesicles and is released into the synapse. Also like other amine neurotransmitters, histamine binds to transmembrane G-protein coupled receptors on the post-synaptic neurons to exert its function.