During the early stages of neuroanatomy exploration, scientists were not sure how neurons transmitted their information. Was it all electrical conduction or did chemicals play a role?
Acetylcholine was the first neurotransmitter to be discovered, and proved the validity of the chemical nature of synapses.
Acetylcholine works both in the Central Nervous System (CNS) and in the Peripheral Nervous System (PNS).
In the PNS, it is famous for being the neurotransmitter used at the neuron muscular junctions, and for being an excitatory (in most cases) neurotransmitter.
Acetylcholine is the name of a neurotransmitter, but the neurons that release acetylcholine are called cholinergic neurons.
There are two types of receptors that are sensitive to acetylcholine: Nicotinic (ionotropic) receptors, and Muscarinic (metabotropic) receptors.
Glutamate is an amino acid that also serves as a neurotransmitter. It is the major excitatory neurotransmiter in the CNS.
There are two major receptors sensitive to glutamate: NMDA receptors (ionotropic) and AMPA (metabotropic) receptors.
NMDA receptors are quite unusual in that they let calcium ions enter the cell. This becomes dangerous when they become overly excited and too much calcium enters the neuron and ends up killing the cell.
ATP (like glutamate) can also serve as an excitatory neurotransmitter. There are both inotropic (P2X) receptors and metabotropic (P2Y) receptors to ATP.
Serotonin is also called 5-hydroxytryptamine (5-HT) and is derived from the amino acid tryptophan.
Serotonin neurons are almost exclusively found in the raphe nucleus, but those neurons have an extremely large range of branches, and are thus involved in many cognitive functions (mood, appetite, sleep, learning and memory).
Except for one ionotropic receptor, most serotonin receptors are metabotropic receptors.
Norepinephrine and Noradrenaline refer to the exact same neurotransmitter. I find the term noradrenaline to be more descriptive, and is used in most countries.
Neurons that produce noradrenaline are called noradrenergic (but not “norepinephric”… another reason why I prefer noradrenaline).
Receptors to noradrenaline are also called noradrenergic receptors.
Norepinephrine is derived from the amino acid tyrosine.
In the brain, noradrenergic neurons are mostly found in the locus ceruleus and in the reticular formation. These neurons also have a very large range of branches and influence many cognitive functions (arousal, decision making, reward, depression, schizophrenia,….).
Just like Norepinephrine, dopamine is also derived from tyrosine.
The reach of dopamine neurons is very extended as well and play a role in reward-learning, schizophrenia, memory, attention, problem-solving, and personality traits.
GABA, (or γ-Aminobutyric acid ) is a derivative of glutamate, but is a major inhibitory neurotransmiter.
There are both ionotropic and metabotropic receptors to GABA. (GABA receptors and GABA producing neurons are called “GABAergic”).
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