What is a Neurotransmitter?
A neurotransmitter is a signalling molecule secreted by a nerve cell to affect the target cell. The target cell can be in glands, muscles, or other neurons.
The Functions
Synapses are microscopic gaps that separate the terminal buttons of one neuron from the receptors of another neuron.
Neurotransmitters are released from the presynaptic neuron to the postsynaptic receptors of the neurons to transmit a chemical or electrical signal.
This process influences everything in our body, including motor, sensory, homeostasis and emotions.
It is known as neurotransmission or synaptic transmission.
Synthesis of Neurotransmitters
Many neurotransmitters are synthesized from amino acids, which require several biosynthetic steps for conversion. Other neurotransmitters are monoamines, neuropeptides, purines and metabolic products.
Types
More than 100 neurotransmitters have been identified, and new ones are still being discovered.
Neurotransmitters are stored in synaptic vesicles and affect neurons in three ways: excitatory, inhibitory, or modulatory.
A neurotransmitter is viewed as “excitatory” when it makes the target cell more likely to fire an action potential.
Examples of excitatory neurotransmitters: acetylcholine, epinephrine, glutamate, histamine, norepinephrine, dopamine
A neurotransmitter is viewed as “inhibitory” when it makes the target cell less likely to fire an action potential.
Examples of inhibitory neurotransmitters: GABA（gamma-aminobutyric acid), serotonin
A neurotransmitter affects neurotransmission without direct excitatory or inhibitory responses to the transmitter. They take action by controlling the presynaptic release or altering the efficacy of action by another neurotransmitter.
Examples of modulatory neurotransmitters: dopamine, serotonin, acetylcholine, histamine, norepinephrine
Disorders May Be Linked To Neurotransmitters
Diseases and disorders may also affect specific neurotransmitter systems. The following are disorders involved in either an increase, decrease, or imbalance of certain neurotransmitters:
Children
- Pediatric Obsessive-Compulsive Disorder(OCD)
Adult
- Alzheimer’s Disease
- Major Depressive Disorder
- Schizophrenia
- Parkinson’s Disease
- Epilepsy
In Summary
Neurotransmitters are essential in balancing signals in the brain. They are crucial in the autonomic nervous system and peripheral nervous system to interconnect in order to maintain brain cognition and responses.
However, health conditions that result from an imbalance of neurotransmitters often require treatment from a professional. See a doctor regularly to discuss physical and mental health concerns.
References:
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2.Takeda A, Tomiyama M, Hanajima R. [The Relationship Between Pathophysiology and Neurotransmitters in Parkinson’s Disease]. Brain Nerve. 2021 Jul;73(7):829-837. Japanese. doi: 10.11477/mf.1416201843. PMID: 34234041.
3.Snyder SH. Neurotransmitters and CNS disease. Schizophrenia. Lancet. 1982 Oct 30;2(8305):970-4. doi: 10.1016/s0140-6736(82)90167-2. PMID: 6127468.