Histamine

Histamine is a biogenic amine chemical involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. New evidence also indicates that histamine plays a role in chemotaxis of white blood cells.

Sleep regulation

Histamine is released as a neurotransmitter. The cell bodies of neurons which release histamine are found in the posterior hypothalamus, in various tuberomammillary nuclei. From here, these histaminergic neurons project throughout the brain, to the cortex through the medial forebrain bundle. Histaminergic action is known to modulate sleep. Classically, antihistamines (H1 histamine receptor antagonists) produce sleep. Likewise, destruction of histamine releasing neurons, or inhibition of histamine synthesis leads to an inability to maintain vigilance in novel situations. Finally, H3 receptor antagonists (which stimulate histamine release) increase wakefulness.

Related Topics:
Hypothalamus - Sleep

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It has been shown that histaminergic cells have the most wakefulness-related firing pattern of any neuronal type thus far recorded. They fire rapidly during waking, fire more slowly during periods of relaxation/tiredness and completely stop firing during REM and non-REM sleep. Histaminergic cells can be recorded firing just before an animal shows signs of waking.

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