up: [[Neuron signaling]] Tags: # Neurotransmitters Neurotransmitters are chemicals released from presynaptic terminals that serve to communicate with postsynaptic terminals. Their most important effect is affecting the membrane potentials of postsynaptic cells. This effect can be an [[Excitatory postsynaptic stimulus (EPSP)]] or an [[Inhibitory postsynaptic stimulus (IPSP)]]. ### Criteria for Being a Neurotransmitter 1. Exists in the presynaptic axon terminal 2. The presynaptic cell contains the correct things to synthesize the neurotransmitters 3. The neurotransmitter is released in significant quantities when an action potential reaches the terminals 4. Specific receptors recognize the neurotransmitter on the postsynaptic neuron 5. Blocking release of the substance prevents presynaptic activity from affecting the postsynaptic cell ### Types of neurotransmitters **Amino acid neurotransmitters:** Mainly comprised of GABA, Glutamate, and glycine. **Amine transmitters:** ==Monoamines== are types of amino acid neurotransmitters that have been modified. Acetylcholine is a big one. Monoamines are split into catecholamine and indoleamine. Catecholamines are comprised of dopamine, epinephrine, and norepinephrine. Indoleamines are comprised of serotonin, melatonin. ^970ad6 **Peptide neurotransmitters:** Made up of short chains of amino acids. **Gas neurotransmitters:** Soluble gases that diffuse between neurons to alter processes. **Excitatory and Inhibitory neurotransmitters:** Glutamate and aspartate are the most common excitatory neurotransmitters in the brain which act on AMPA ionotropic receptors to cause depolarization. GABA and glycine, however, are the main inhibitory. This probably has to do with the fact that they facilitate Cl- ions into the cell. ## Most Important Neurotransmitters #### Dopamine [[Dopamine]] is a type of [[Neuropharmacology#^970ad6|catecholamine]] widely regarded as the pleasure hormone but as is said in [[Dopamine Nation]] it's better described as the motivation hormone. Dopamine has a lot to do with addiction and according to the [[Dopamine#^eba41c|The Dopamine Reward Hypothesis]] the more dopamine is released with a certain action the more you will want to do that action. Pathway in the brain: ![[Pasted image 20220915185448.png]] #### Serotonin Serotonin is a type of [[Neuropharmacology#^970ad6|indoleamine]] that is associated with feelings of relaxation or contentment. This is why it's used in a lot of [[Neuropharmacology#^cea3a3|anti-depressents]]. Pathway in the brain: ![[Pasted image 20220915190015.png]] #### Glutamate Glutamate is an amino acid transmitter. It's the most common excitatory transmitter. ###### What's the most common Glutamate receptor and how does it function? The most common Glutamate receptors are the AMPA and NMDA receptors. The NMDA receptor is voltage and ligand gated meaning glutamate must bind on and it must be depolarized. Once this happens the Mg2+ ion on the inside of the cell is removed and Ca2+ is allowed into the neuron leading to its depolarizing quality. ![[Pasted image 20220902103250.png]] #### GABA GABA is a amino acid neurotransmitter. It's the most common inhibitory transmitter. #### Acetylcholine Acetylcholine is a type of amine neurotransmitter which facilitates muscular contraction. Because of this it has a massive influence on the muscles in the body which is why [[Action potentials#^72e35c|curare]] stops muscular contraction. #### Norepinephrine Norepinephrine is a type of catecholamine that has very similar effects to epinephrine or adrenaline meaning it gives energy. It's more involved in arousal than feeling good. It is a precursor to Dopamine. Pathway in the brain: ![[Pasted image 20220915185528.png]] Related: