Neurotransmitters
<p>Oct 29, 2009 3:05 PM
 
90% of the synapses in the human brain user glutamate - excitatory
Next most prevalent is GABA - used at 90% oof the remaining 10% of synapses.
 
Addictive drugs:  cocaine, amphet, heroin,  exert their effect maily thru dopaminergic system.
 
Here are a few examples of important neurotransmitter actions:</p>
<ul>
<li><a title="Glutamate" href="/wiki/Glutamate" class="mw-redirect">Glutamate</a> is used at the great majority of <b>fast excitatory synapses in the brain and spinal cord.</b> It is also used at most synapses that are<b> "modifiable"</b>, i.e. capable of increasing or decreasing in strength. Modifiable synapses are thought to be the main memory-storage elements in the brain.</li>
<li><a title="GABA" href="/wiki/GABA" class="mw-redirect">GABA</a> is used at the great majority o<b>f fast inhibitory synapses in virtually every part of the brain.</b> Many sedative/tranquilizing drugs act by enhancing the effects of GABA. Correspondingly <a title="Glycine" href="/wiki/Glycine">glycine</a> is the inhibitory transmitter in the spinal cord.</li>
<li><a title="Acetylcholine" href="/wiki/Acetylcholine">Acetylcholine</a> is distinguished as the transmitter at the <a title="Neuromuscular junction" href="/wiki/Neuromuscular_junction">neuromuscular junction</a> connecting motor nerves to muscles. The paralytic arrow-poison <a title="Curare" href="/wiki/Curare">curare</a> acts by blocking transmission at these synapses. Acetylcholine also operates in many regions of the brain, but using different types of receptors.</li>
<li><a title="Dopamine" href="/wiki/Dopamine">Dopamine</a> has a number of important functions in the brain. It plays <b>a critical role in the <a title="Reward system" href="/wiki/Reward_system">reward system</a>, </b>but dysfunction of the dopamine system is also implicated in <a title="Parkinson's disease" href="/wiki/Parkinson%27s_disease">Parkinson's disease</a> and <a title="Schizophrenia" href="/wiki/Schizophrenia">schizophrenia</a>.</li>
<li><a title="Serotonin" href="/wiki/Serotonin">Serotonin</a> has a number of important functions that are difficult to describe in a unified way, including <b>regulation of <a title="Mood (psychology)" href="/wiki/Mood_(psychology)">mood</a>, <a title="Sleep" href="/wiki/Sleep">sleep/wake cycles</a>,</b> and <a title="Thermoregulation" href="/wiki/Thermoregulation">body temperature</a>. It is released during sunny weather, and also when eating chocolate or taking Ecstasy (MDMA).<sup title="This claim needs references to reliable sources from June 2009" class="noprint Template-Fact">[<a title="Wikipedia:Citation needed" href="/wiki/Wikipedia:Citation_needed"><i>citation needed</i></a>]</sup></li>
<li><a title="Substance P" href="/wiki/Substance_P">Substance P</a> undecapeptide responsible for transmission of pain from certain sensory neurons to the central nervous system.</li>
</ul>
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