A neurotransmitter (neurotransmitter, neuromediator) is a chemical molecule that allows the transmission of signals between nerve cells, but not only. The neurotransmitter is both the amine serotonin and the hormone vasopressin or the amino acid glycine. What other neurotransmitters are distinguished in humans and what happens when the number of individual neurotransmitters in the body is disturbed?

The neurotransmitter( neurotransmitter ,neuromediator ) are chemical molecules by which individual cells nerves communicate with each other, this was proved in 1921 by the German pharmacologist Otto Loewi. Neurotransmitters are substances that are typically produced within and released from nerve cells. Neurons - through neurotransmitters - send nerve signals not only to other cells of the nervous system, but also to muscle cells or cells belonging to the endocrine glands.

Currently, more than 100 different neurotransmitters are distinguished, and more are still being discovered. There is a puzzling aspect, however: in nerve cells, information is sent as electrical stimuli, so what do chemical substances in the form of neurotransmitters have to the phenomena associated with electricity?

Neurotransmitters: Physiology of Action

In nerve cells, neurotransmitters are classically stored in specific structures called synaptic vesicles. Here it comes to an explanation of the relationship between electrical and chemical impulses in neurons. Well, synaptic vesicles are usually located near one of the elements of the synapse (which is the connection between two nerve cells or a nerve cell and a muscle cell), which is the presynaptic ending. Reaching the end of the presynaptic electrical impulse leading to its depolarization leads to the attachment of synaptic vesicles to the presynaptic membrane. Eventually, the neurotransmitter is exocytosed (released) into the synaptic cleft.

The mere fact that a neurotransmitter is between the pre- and postsynaptic terminals is not sufficient to transmit a signal between cells. For this to happen, the neurotransmitter must bind tolocated within the postsynaptic membrane with its characteristic receptors.

What happens when a neurotransmitter attaches to a receptor depends, for example, on the type of neurotransmitter. There are excitatory neurotransmitters which - as soon as they reach the postsynaptic terminal in the right amount - lead to the depolarization of the nerve cell and to send the impulse transmitted through the synapse. In turn, inhibitory neurotransmitters act differently, their effect is the occurrence of hyperpolarization, i.e. a state in which the excitability of the nerve cell is reduced.

Neurotransmitters: examples of neurotransmitters

Today more than 100 neurotransmitters are listed, and scientists every now and then discover new substances that can also be included in this group. In fact, neurotransmitters are extremely wide variety of compounds, examples of the most important neurotransmitters are:

  • glutamic acid
  • γ-aminobutyric acid (GABA)
  • glycine
  • serotonin
  • dopamine
  • noradrenaline (norepinephrine)
  • adrenaline (epinephrine)
  • histamine
  • adenosine
  • hormones (such as vasoactive intestinal peptide, oxytocin, and vasopressin)
  • endogenous opiates (e.g. dynorphine, endorphins)
  • neurokinins
  • acetylcholine
  • nitric oxide

The chemical structure of individual neurotransmitters can be very diverse. The neurotransmitters include both amino acids (such as glycine), peptides (such as substance P), purine derivatives (such as adenosine) and monoamines (such as, for example, noradrenaline or dopamine).

Neurotransmitters: examples of how different neurotransmitters work

Various neurotransmitters differ from each other not only in their structure, but also in the places of the body where they are most abundant, and in the effects they exert.

Dopamineis a neurotransmitter that exhibits distinct activities in different parts of the nervous system. Within the structures of the pyramid system, dopamine corresponds, inter alia, to for coordination of movements and muscle tension. In the limbic system, this neurotransmitter influences our emotions, while in the structures of the endocrine system, the task of dopamine is to control the secretion of hormones - dopamine is sometimes also called prolactostatin because it reduces the release of prolactin.

Serotoninis a neurotransmitter that is sometimes called the "happiness hormone". Serotonin is produced not only withinthe nervous system, but also, among others in the digestive tract or in platelets. This neurotransmitter is related to our mood, but also regulates sleep, has an impact on appetite and drive behavior.

γ-Aminobutyric acid (GABA)is one of the essential inhibitory neurotransmitters in the nervous system. It is under the influence of its action that we can calm down and calm down, the effect of the inhibitory effect of GABA is also the reduction of the severity of anxiety. It would seem theoretically that in the absence of GABA, people could be active all the time - after all, then nothing would inhibit the activity of the nervous system. However, such a situation would be definitely unfavorable - GABA deficiency could lead to such hyperactivity of nerve cells, which would lead to harmful stimulation, even associated with the feeling of extreme anxiety.

Endogenous opioids , such asendorphins , are another type of happiness neurotransmitter. Their effects can even result in euphoric states, in addition to this type of neuromodulators of this type, they can lead to a suppressed feeling of such unpleasant sensations as pain or numbness.

Adrenaline- a substance known primarily as a drug in many different life-threatening conditions - is in turn a neurotransmitter that controls the activity of the adrenal glands, but also affects the course of sleep. In addition, it is adrenaline that is the basic neurotransmitter of the sympathetic system, and it is responsible for mobilizing the body in stressful situations.

Neurotransmitters: diseases related to the neurotransmitter systems

It probably comes as no surprise that disturbances in the number of neurotransmitters in the body are considered as potential causes of various diseases.

For example, serotonin deficiencies are one of the possible causes of depressive states in people. Serotonin generally attracts the attention of scientists because its deficiency in the body can theoretically lead to insomnia and aggressive behavior, but it can also contribute to the development of binge eating in people.

Dopamine and its abnormalities in the body are primarily associated with two entities. In psychiatry, it is noted that in patients with schizophrenia, some parts of the brain may develop excessive dopaminergic activity (contributing to the development of productive symptoms such as hallucinations and delusions in this disease), and insufficient dopaminergic activity in other parts of the brain. Dopamine is also associated with another, this time neurological disease, which is the diseaseParkinson's disease - it is the deficiencies of this neurotransmitter that lead to the occurrence of motor dysfunction in patients.

Diseases related to neurotransmitters can also be dementia. Such a dependence is possible, for example, in the case of Alzheimer's disease, in which patients may experience acetylcholine deficiency, i.e. deficiency of the neurotransmitter associated, among others, with with memory processes.

Neurotransmitters: the effect on neurotransmitters is used by doctors, but not only by them …

The effects affecting the neurotransmitter systems have been used by doctors for a long time. We can mention here, for example, the administration of dopamine precursors in the form of levodopa to patients with Parkinson's disease or antidepressants, among which the most popular are preparations that reduce serotonin reuptake (these preparations are briefly referred to as SSRIs). In the case of dementia patients, drugs from the group of acetylcholinesterase inhibitors are recommended, which - by inhibiting the enzyme that breaks down acetylcholine - lead to an increase in the amount of this neurotransmitter in the patients' bodies.

The above-described influence on the neurotransmitter systems seems to be the most justified, unfortunately - the knowledge of information about neurotransmitter systems is also used for definitely illegal purposes. An example is the rape pill - the substance contained in it, γ-hydroxybutyric acid, is a naturally occurring neurotransmitter that is formed in the human body from γ-aminobutyric acid. However, the neurotransmitter in the form of butyric acid is present in humans in small amounts, while rape pills contain large amounts of this substance. Γ-hydroxybutyric acid is one of the inhibitory neurotransmitters - consumption of high doses of it may lead to such inhibition of the nervous system, which will result in memory impairment, drowsiness or even loss of consciousness. It is precisely these properties of the said compound that are responsible for the actions exerted by the rape pills, which are unfortunately still present in our reality.

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

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Neurology