Neurotransmitters: Structure, Function & Diseases

Neurotransmitters are something like the couriers of our body. They are biochemical substances that have the task of transmitting signals from one nerve cell (neuron) to the next. Without neurotransmitters, the control of our body would be completely impossible.

What are neurotransmitters?

The term neurotransmitter already describes the usefulness of these messenger substances very well, because they are responsible for interneuronal transmission – the transmission between nerve cells. In this context, the term refers to a wide variety of substance classes, which are united under it merely according to their specific benefits. In common parlance, neurotransmitters are often mistakenly equated with hormones. However, hormones are substances that are released into the bloodstream, whereas neurotransmitters are restricted to the area of action between synapses.

Medical and health functions, roles, and meanings.

Neurotransmitters are released from the synapses at the end of the neuron into what is called the synaptic cleft when a neuron is activated. The synaptic cleft is located where two neurons “dock” with each other. When a neuron receives a signal, it travels through the entire length of the neuron to its end. To pass to the next neuron, a biochemical reaction takes place in the presynaptic cleft: Neurotransmitters are released from the synapse into the synaptic cleft. Now these neurotransmitters can dock to receptors of the synapse of the next neuron and transform the channels in such a way that the ion channels open briefly. Now calcium ions can flow in, which changes the electrical potential of the neuron. This is how the signal is transmitted. However, the binding of the neurotransmitters to the synapse is only of limited duration – due to the polarization, the neurotransmitters detach themselves again from the docking station of the synapse and are taken up again by the presynaptic neuron in the synaptic cleft. There they remain, packed in so-called transport vesicles, until their next use. It is important to keep in mind that this process takes place quickly, in minimal fractions of seconds, given the conduction speed of signals in our nervous system. How quickly one perceives pain, how quickly one recognizes things, and how quickly one can respond depends largely on the rate at which neurotransmitters are released into the synaptic cleft.

Diseases, ailments, and disorders

Neurotransmitters thus occur within nerve cells, at synapses, where they are packaged in transport vesicles awaiting their use. Such neurons are found in both the central nervous system (CNS) and the peripheral nervous system. The most common neurotransmitter in the peripheral nervous system is acetylcholine from the subgroup of biogenic amines. Within the CNS, glutamate is the most important neurotransmitter. Other relevant CNS neurotransmitters include GABA, glycine, serotonin, norepinephrine, and dopamine. Many of these neurotransmitters are already familiar in connection with certain drugs, and no wonder:

Drug use has a particular effect on the function of neurotransmitters in the brain. The stimulant amphetamine (in scene circles “speed”), for example, causes the release of the neurotransmitters norepinephrine and dopamine. This causes stimulation of the sympathetic nervous system, which then contributes to the onset of the fight-or-flight reflex. Strong alertness, vigilance and insensitivity to pain and hunger can be observed – just one of the reasons why amphetamine was used as a soldier drug in war. Alcohol consumption also affects neurotransmitters, or rather their receptors: Inhibition of NMDA receptors and simultaneous stimulation of GABA receptors inhibits stimulus transmission. Reactions are now slower, less controlled, the reaction speed is slowed down and environmental stimuli are no longer interpreted correctly. Hallucinogens, such as LSD, also directly affect the functioning of neurotransmitter transport. Neurotransmitters also have a strong impact on psychiatric diseases, such as acute schizophrenic psychosis: For example, overactivity of the neurotransmitter dopamine often underlies an acute psychosis. Also a pathological function of the neurotransmitter glutamate, is hotly discussed as a cause for schizophrenia again and again.The fact is that psychosis can be counteracted by drugs that affect neurotransmitters.