Neurotransmitters

Definition - What is a Neurotransmitter?

The human brain consists of an almost unimaginable number of cells. An estimated 100 billion neurons, which do the actual thinking work, and just as many so-called glial cells, which support the neurons in their work, form the organ that makes us humans something special in this world. In order for these nerve cells to communicate with one another, a complex system of messenger substances, the neurotransmitters, developed in the course of evolution. There are a little more than two dozen, sometimes very different, chemical compounds, which can be divided into different groups according to different aspects.

The most common classification is based on their chemical structure. For example, there is a small group of soluble gases, to which carbon monoxide (CO) and nitrogen monoxide (NO) belong, but also a large group of amino acids, the building blocks of proteins that function as neurotransmitters. Proteins themselves also form a group of neurotransmitters.

That this extensive System of messenger substances in the brain Remaining in equilibrium is of enormous importance because of a deficiency or excess of neurotransmitters devastating consequences for the functioning of our nervous system. Depending on which part of the brain the imbalance occurs in, this can affect both ours mental, as well as physical health knock down. Diseases like Parkinson's disease, the schizophrenia and also depressions are at least partly the result of Changes in brain chemistry. On the other hand, we can also use our knowledge of the messenger substances of the nervous system to treat precisely these diseases.

By the way, neurotransmitters are by no means to be equated with hormones. While hormones are released into the bloodstream and circulate to their target organs, neurotransmitters are only used for Communication within the nervous system.

Duties of the neurotransmitters

Within individual nerve cells (neurons), which in humans sometimes have more than one meter long can be, the information is transmitted via electrical voltage, comparable to power cables. However, this line is regularly interrupted when the forwarding of the information from one neuron should take place on another. This is where the chemical component of the transmission of information in the brain with the help of neurotransmitters comes into play. The contact points between the neurons, where the chemical information transfer takes place, are called Synapse designated. About a trillion of them exist alone in our brain. Transferred to the number of neurons themselves, this means that every single nerve cell is cut connected to 1000 other nerve cells is.

The task of the neurotransmitter is to bridge the interruption of the electrical impulse between two neurons. This is done by applying the impulse arriving at the synapse to Release of neurotransmitters from their storage vesicles (den Vesicles) leads from neuron A into the synaptic cleft. In this gap, just a few nanometers wide, between the neurons, the messenger substances diffuse to the corresponding receptors on neuron B. Here the chemical information is converted back into electrical information.

The effect that each individual neurotransmitter achieves is very much dependent on the brain region in which this mechanism takes place. As a result, a certain neurotransmitter a variety of tasks takes over in different areas of the brain. It is important to know that neurotransmitters not always exciting act on the downstream nerve cell, but also inhibiting can affect the electrical transmission of information.

GABA

GABA is a very good example of an inhibiting (inhibitory) acting neurotransmitter, since it is the most widespread and therefore perhaps most important inhibiting messenger substance is in the central nervous system. The term GABA is only an abbreviation for his name "y-aminobutyric acid" (in English gamma-aminobutyric acid). Because of its inhibitory effects, GABA is sometimes called endogenous sedative described. This is made use of in medicine, in that many drugs have now been developed that target the GABA receptors work. These include, for example Barbiturates and Benzodiazepines, Which calming, sedating, and antispasmodic Have properties. Apart from that, GABA does not only play a role in the brain and spinal cord. It is also important in the body's insulin metabolism, as it depends on the pancreas is produced.

Glutamate

As Food additive and Flavor enhancers The amino acid is found in a wide variety of ready meals Glutamate most people know it. However, glutamate is much more important to us than most important exciting (excitation-proof) Neurotransmitters in our nervous system. In a sense, this makes glutamate the antagonist of GABA. The two messenger substances are also very close to one another, since GABA (γ-aminobutyric acid) is produced by the body from glutamate. As far as we know today, glutamate plays primarily for them Control of movement, our memory, Learning processes and the Sensory perception a major role. At the same time there is a connection between insomnia and a disturbed glutamate balance suspected, as well as a connection of the messenger substance to the development epileptic seizures.

Dopamine

Dopamine is perhaps one of the most famous neurotransmitters. This is mainly due to its connection to the origin of the Parkinson's disease. With this disease it gradually comes to Downfall of neurons those located in the midbrain Substantia nigra (from Latin "black substance"), which as Part of the motor system dopamine produced. The result are the typical symptoms Sedentary lifestyle, Stiffness of the limbs, and Tremors of rest.

In later stages there are other neurological and psychological symptoms such as depressions and dementia symptoms added. From this it can be deduced what an important role dopamine plays in, among other things Process of motor functions plays.

In addition, however, dopamine is also essential for our proper functioning attention and Ability to learn indispensable. In addition, dopamine is fundamental to the function of the Reward system of our brain and therefore ours as well motivation involved. This can be felt, among other things, in the effect of drugs, be it alcohol, Cigarettes or illegal drugs like marijuana or cocaine, their psychic Addiction is based on the increased release of dopamine in the reward system.

However, more everyday activities, such as eating or having sexual intercourse, act on exactly this system. Incidentally, dopamine is also transformed into the body with the adrenaline relative Norepinephrine synthesized, which among other things is involved in the control of Emotions, alertness And also motivation is involved.

depressions

The depression is a very common mental disorder that is mainly characterized by negative thoughts and moods and the Loss to joy, interest, drive and Self esteem makes noticeable. This makes the depression one of the so-called mood disorders. Even healthy people may experience symptoms like this from time to time, but they are less severe and less common. Women are about twice as often how men are affected by depression. Depression is also more common in high-income countries.

The mechanisms behind depressive disorders are still only partially understood due to their complexity. However, the most common theory of what causes depression is based on one multifactorial development model. Among other things genetic, medicinal, hormonal, neurobiological and developmental risk factors used as an explanation for the occurrence of depression. What is certain is that there are disturbances at the level of signal transmission by neurotransmitters. A number of different signaling systems appear to be affected by this.

However, they play a special role Serotonin, norepinephrine and Dopamine system. All three neurotransmitters seem to be in, but to a different extent individually for each patient too small amounts to be poured out. This knowledge is used in the therapy of depression. Multiple groups of Antidepressants specifically intervene in the norepinephrine, serotonin and dopamine systems of the brain by using the Resumption inhibit this neurotransmitter. This becomes the present Neurotransmitter deficiency counteracted so that the symptoms are alleviated. Various groups of drugs are now available for this purpose. Tricyclic antidepressants Nowadays, however, due to the sometimes severe side effects, they are rarely used, while the group of Serotonin reuptake inhibitors (SSRI) and Norepinephrine reuptake inhibitors (SNRI) have good effects and milder side effects.

Serotonin

Serotonin, also Enteramine called, is a so-called biogenic amine, which is both a hormone and a neurotransmitter. As such, it plays in both Central nervous system, as well as in Intestinal nervous system and in its function as a hormone im Cardiovascular system a major role. Its name is derived from the words serum and tonus (tension). One of its effects can be derived from this, namely that it acts as part of the blood serum on the tension in the blood vessels and thus on the blood pressure. As a messenger substance in the nervous system, it is primarily known as a mood maker. This is mainly its influence on appetite, Sex drive and our mental wellbeing attributable to. A deficiency of this neurotransmitter has so among other things depressions result.
In addition, however, it is also in almost all other brain functions, such as the Sensation of pain, our Sleep-wake rhythm and the Temperature regulation involved. It practices here both inhibiting, as well as exciting functions in communication between neurons. The serotonergic pathways of the nervous system named after him are distributed over the whole brain in a complex system connected to the other neurotransmitters.

Acetylcholine

Our nervous system can be roughly divided into three different sections - that central nervous systemto which our brain and the Spinal cord belong that autonomic nervous system, which influences organ functions such as heartbeat, breathing and digestion, and that peripheral nervous systemwhich enables us to work with muscles and tactile sensitivity, among other things.

Acetylcholine is by far the most important transmitter in the peripheral nervous system and is for example for the transmission of signals of the nerve cords of the Spinal cord on the muscles responsible. In the vegetative nervous system, it is the most important neurotransmitter alongside norepinephrine. Its importance in the central nervous system becomes particularly evident when it is present in too low concentrations. This is for example with the Alzheimer's dementia the case. Here it comes to a total of one Numerous neurons die in the cerebrum, however, nerve cells producing acetylcholine are mainly affected. The resulting deficiency can, at least in part, be treated with medication, so-called Acetylcholinesterase inhibitors administered. Because the enzyme Acetylcholinesterase is responsible for the breakdown of acetylcholine, a higher concentration of the messenger substance in the synaptic gap can be achieved and the symptoms of dementia can be alleviated. However, this is just one example of the importance of acetylcholine in medicine. A wide variety of drugs that intervene in the acetylcholine system are used, among other things, in ophthalmology, but also in other medical fields.