The A – Z Of Neurotransmitters and Its Medical Importance

Different Neurotransmitters and Their Importance

Neurotransmitters are endogenous chemicals that enable neurotransmission. It is a type of chemical messenger that transmits signals across a chemical synapse, such as a neuromuscular junction, from one neuron to another “target” neuron, muscle cell, or gland cell.


In other words, neurotransmitters are the chemical substances manufactured in the neuron that aid in the transmission of information throughout the body. They either excite or stimulate action in the cells (excitatory) or inhibit or stop an action (inhibitory)

These neurotransmitters are necessary for just the right proportions to relay messages across the synapses. Major neurotransmitters have been found to play a role in psychiatric illness as well as in the actions and side effects of psychotropic drugs.

Acetylcholine (ACh)


Location: neuromuscular junction, CNS

It is found in the brain, spinal cord, and peripheral nervous system, particularly at the neuromuscular junction of skeletal muscle. It is synthesized from dietary choline found in red meat and vegetables. It can be excitatory or inhibitory. It involved in thought, learning, and memory. Activates muscle action in the body. It also associated with attention and awakening. One of the primary functions of acetylcholine is to carry signals from motor neurons to the body’s skeletal muscles.

Low levels of acetylcholine(Ach) are seen in Alzheimer’s disease and people with myasthenia gravis have reduced acetylcholine receptors.


Fight or Flight

Location: Adrenal Medulla

Produced in stressful situations, increases heart rate and blood flow, leading to physical boost and heightened awareness



Location: Adrenal Medulla

Noradrenaline or norepinephrine is the most prevalent neurotransmitter in the nervous system. It plays a role in attention, learning and memory, sleep and wakefulness, and mood regulation. Excess norepinephrine has been implicated in several anxiety disorders, deficits may contribute to memory loss, social withdrawal, and depression. Some antidepressants block the reuptake of norepinephrine, whereas others inhibit MAO from metabolizing it.

Affects attention and responding actions in the brain. Contracts blood vessels, increasing blood flow



Location: Hypothalamus, Brain Stem

Dopamine, a neurotransmitter located primarily in the brain stem, has been found to be involved in the control of complex movements, motivation, cognition, and regulation of emotional responses. It is generally excitatory and is synthesized from tyrosine. Antipsychotic drugs work by blocking dopamine receptors and reducing dopamine activity

Feelings of pleasure also addiction, movement, and motivation. People repeat behaviors that lead to dopamine release

High dopamine levels are seen in Schizophrenia

Low dopamine levels are seen in Parkinson’s disease



Location: Gut, CNS

Serotonin is derived from tryptophan, a dietary amino acid. The function of serotonin is mostly inhibitory, and it is involved in the control of food intake, sleep and wakefulness, temperature regulation, pain control, sexual behavior, and emotions. It contributes to well-being and happiness. It helps the digestive system regulation. Affected by exercise and light exposure. Some antidepressants block the serotonin reuptake, thus leaving it available longer in the synapse, which results in improved mood.

Low levels of serotonin are seen in depression

High levels of serotonin are seen in mania

GABA (Gamma Amino Butyric Acid)


Location: Brain

It regulates moods, improves sleep and reduces anxiety

It calms firing nerves in the central nervous system. It is the major inhibitory neurotransmitter in the brain and has been found to modulate other neurotransmitter systems rather than to provide direct stimulus. High levels improve focus, low levels cause anxiety. It also contributes to motor control and vision. Drugs that increase GABA function, such as benzodiazepines, are used to treat anxiety and to induce sleep.

Low levels of GABA are seen in Anxiety



Location: CNS, PNS

The glutamate is an excitatory amino acid that at high levels can have a neurotoxic effect. Most common neurotransmitter. It involved in learning and memory. It regulates the development and creation of nerve contacts

High levels of glutamate linked with OCD



Released during exercise, excitement, and sex. It produces well-being and euphoria, also reduces pain


It is involved in peripheral allergic reactions, control gastric secretions, cardiac stimulation, and alertness. Some psychotropic drugs block histamines, resulting in weight gain, sedation, and hypotension.


Octopamine is an organic chemical closely related to norepinephrine and synthesized biologically by a homologous pathway. Its name derives from the fact that it was first identified in the salivary glands of the octopus.

In many types of invertebrates, octopamine is an important neurotransmitter and hormone. 

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