Histamine is a slow-acting neurotransmitter and affects the central nervous system (CNS)
activity. The central actions of histamine are mediated through its four distinct G-protein
coupled, i.e. H1, H2 or H3 receptors, which are widely expressed in distinct patterns in the
mammalian brain and also through H4 mainly thought to be restricted to hematopoietic cells
and is suggested to mediate functions of the immune system and chemotaxis, have also been
found to modulate CNS actions. The central presence of histaminergic system was
ascertained immunohistochemically with the origin in the tuberomammillary (TM) nucleus, a
part of the posterior hypothalamus, with wide distribution of histaminergic projections to the
rest of the CNS. The histamine actions are regulated by histamine H3 receptor, which is an
inhibitory autoreceptor or heteroceptor that controls histamine synthesis and release of
histamine and other neurotransmitters in the brain, such as acetylcholine, norepinephrine,
serotonin, dopamine or GABA located on the somata and axon terminals of histamine
neurons. The present report is the compilation of the central role of histamine via its
receptors.
