4 Types of Neurotransmitters | Their Physiology and Functions
Neurotransmitters are the chemical messengers which are part of the nervous system.
They help the brain and spinal cord to control and regulate the whole body.
They are mostly formed in the nerves and released at the neuronal junctions.
There are many neurotransmitters in the body involved in different functions.
They can be classified based on their
- Chemistry
- Physiological effects
- Functions in the body.
Types of Neurotransmitters
Based on chemistry there are four types:
a) Monoamines
b) Aminoacids
c) peptides
d) Cholines
Monoamines: These are also called biogenic amines. They form the most extensive set of neurotransmitters (NT’s) and control many vital functions in the body.
Examples include; Dopamine, Norepinephrine, epinephrine, serotonin, and histamine. Except for serotonin and histamine, remaining others form a part of the sympathetic system and also called as catecholamines. While histamine plays a crucial role in wound healing and allergy. Whereas serotonin regulates stress and even emotions like anxiety, depression, memory, etc.
Aminoacids: These are the ones which are essential aminoacids but have the neurotransmitter function.
Ex: glutamine, glycine, GABA.
Glutamate is an excitatory type of transmitter in the brain. It is formed from the amino acids glutamine. The glycine and GABA are an inhibitory type of transmitters.
Peptides: These are large molecule NT’s in the body. Their chemical structure is a polymer of amino acids. They are vast and limited and specific function in the body.
Examples include opioid peptides like endorphin, enkephalin, dynorphin, adrenorphin, aminorphin, leuomorphin, etc.
They bind to opioid receptors and execute their function mostly in pain, emotion, food intake, etc.
Choline based: These have a choline moiety in them bound to an organic acid.
These include Acetylcholine, butyrylcholine. Both of them are chemical transmitters in the parasympathetic system. But acetylcholine forms a significant portion of it. They execute their function through their action on the muscarinic and nicotinic receptors.
