Editing Excitatory synapse (section)

==Types of excitatory neurotransmitters==

===Acetylcholine===
:[[Acetylcholine]] (ACh) is an excitatory, small-molecule neurotransmitter involved in synaptic transmission at [[neuromuscular junction]]s controlling the [[vagus nerve]] and [[cardiac muscle]] fibers, as well as in the skeletal and visceral [[motor system]]s and various sites within the central nervous system.<ref name="Neuroscience, 4th ed."/> This neurotransmitter crosses the synaptic cleft and binds to a variety of postsynaptic receptors depending on the [[species]], but all of these receptors depolarize the postsynaptic membrane and thus classify ACh as an excitatory neurotransmitter.<ref name="WormBook">{{cite web |url=http://www.wormbook.org/chapters/www_acetylcholine/acetylcholine.html |title=Acetylcholine |author=J. Rand |year=2007}}</ref>

===Glutamate===
:[[Glutamic acid|Glutamate]] is a small, amino acid neurotransmitter, and is the primary excitatory neurotransmitter at almost all synapses in the central nervous system.  This molecule binds multiple postsynaptic receptors including the [[NMDA receptor]], [[AMPA receptor]], and [[kainate receptor]]s.  These receptors are all [[cation]] [[ion channel|channels]] that allow positively charged ions such as Na<sup>+</sup>, K<sup>+</sup>, and sometimes Ca<sup>2+</sup> into the postsynaptic cell, causing a depolarization that excites the neuron.<ref name="Neuroscience, 4th ed."/>

===Catecholamines===
:The [[catecholamine]]s, which include [[Epinephrine]], [[Norepinephrine]], and [[Dopamine]], are excitatory biogenic amine [[Neuromodulation|neuromodulators]] that are derived from the amino acid [[tyrosine]] and serve as excitatory neurotransmitters at various locations in the central nervous system as well as the [[peripheral nervous system]].  Epinephrine and norepinephrine, also called [[adrenaline]] and noradrenaline, respectively, bind a number of G-protein-coupled receptors that induce their depolarizing effects on the postsynaptic cell in various ways, including activating and inactivating certain K<sup>+</sup> channels.  Epinephrine is found in the [[Tegmentum|lateral tegmental system]], [[Medulla oblongata|medulla]], [[hypothalamus]], and [[thalamus]] of the central nervous system, but their function is not fully understood.  Norepinephrine is found in the [[brain stem]] and is involved in sleep and wakefulness, feeding behavior, and attention.  Dopamine binds to G-protein-coupled receptors in many areas of the brain, especially the [[corpus striatum]] where it mediates the synaptic transmission that underlies the coordination of body movements.<ref name="Neuroscience, 4th ed."/>

===Serotonin===
:[[Serotonin]] is an excitatory neurotransmitter that regulates sleep and wakefulness and is found in neurons of the [[Raphe nuclei|raphe]] region of the pons and upper brain stem, which extend into the [[forebrain]].  Serotonin binds a number of receptors, including the 5-HT<sub>3</sub> receptors, which are ligand-gated ion channels that allow the passage of cations in order to depolarize the membrane potential of the postsynaptic neuron that they reside on.<ref name="Neuroscience, 4th ed."/> Levels of serotonin activity that are lower than normal have been linked to a variety of symptoms, especially [[Major depressive disorder|depression]], which is why many [[antidepressant|antidepressant drugs]] act to increase serotonin activity.<ref name="The Human Brain Mind Center">{{cite web |url=http://www.nutramed.com/brain/neurotransmitters_serotonin.htm |title=Neurotransmitter - Serotonin |author=Stephen Gislason |publisher=Brain Mind Center at Alpha Online |year=1995}}</ref>

===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>