Editing Excitatory synapse (section)

===Histamine===
:[[Histamine]] acts as an excitatory neurotransmitter by binding G-protein coupled receptors in neurons of the hypothalamus. These neurons project into many regions of the brain and spinal cord, allowing histamine to mediate attention, arousal, and [[allergy|allergic responses]].<ref name="Neuroscience, 4th ed."/> Of the four types of histamine receptors (H<sub>1</sub> - H<sub>4</sub>), H<sub>3</sub> is found in the central nervous system and is responsible for regulating histamine effects on neurotransmission.<ref name="Pathophysiology of the Endocrine System">{{cite web |url=http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/histamine.html |title=Histamine and Histamine Receptors |author=R. Bowen |year=2008}}</ref>