11 October 2016

Neurotransmitters, part 3

Opioid peptides

Atlas, Geektimes

In the first two texts, Atlas talked about monoamine mediators and their assistants - inhibitory and stimulating neurotransmitters. This time we will talk about small tricky molecules-peptides, which play an important role in the life of the body – bring joy and relieve pain.

What kind of peptides are these

Peptides are small molecules that consist of several amino acid residues. Size is the only thing that distinguishes a peptide from a protein: as soon as the number of residues reaches 50, the polypeptide begins to be called a protein. Peptides are synthesized in different tissues of the body. Each peptide has its own precursor – a precursor protein, from which the peptide is obtained during hydrolysis (splitting).

The main function of peptides is the transfer of information between cells. The body actively uses peptides for a variety of needs – to protect against toxins and bacteria (peptides are now one of the most promising antibiotics), cell regeneration, appetite regulation, pain relief – and this list can be supplemented indefinitely. In a word, peptides are thousands of tireless project managers, without whom nothing works.

Opioid Peptides

This is a group of peptides that interact with opioid receptors. These include the famous endorphins, as well as enkephalins and dynorphins.

The name "endorphins" comes from the phrase "endogenous morphines" – morphines synthesized by the body itself. They block the transmission of pain impulses and affect the emotional state of a person. It is believed that a high concentration of endorphins causes a feeling of euphoria, but other neurotransmitters also influence the formation of this state.

The brain increases the production of endorphins in response to pain, although there are other ways to raise their concentration. One of them is long–distance running (it is endorphins that cause the "euphoria of the runner"); the other is to laugh a lot, and preferably in good company. Your favorite music and dancing will also help.

There are several types of endorphins. Alpha-endorphins affect emotions and motor activity. Gamma endorphins, on the contrary, reduce emotional activity. Beta-endorphins are the most active agent of interaction with opioid receptors, they are responsible for analgesia and activation of the reward system. Beta-endorphins are the first to react to inflammatory processes.

Enkephalins and dinorphins are similar in structure and action to endorphins in many ways, only they originate from other precursors and interact differently with opioid receptors. According to research, the effectiveness of dynorphin as an analgesic is 6 times higher than the effectiveness of morphine.

Opioid receptors

There are four types of opioid receptors – mu, delta, kappa and nociseptin receptor. Mu receptors are encoded by the OPRM1 gene and control the process of pain relief and interaction with the dopamine reward system. Therefore, these receptors are associated with an interest in food, the learning process and the formation of social attachments. Mutations in the gene are associated with the formation of dependence on nicotine, cocaine and alcohol. Mu receptors interact with beta-endorphins and enkephalins.

Delta receptors also interact with endorphins and enkephalins, but to a lesser extent affect the reward system than mu receptors. Kappa receptors differ in their action: in addition to anesthesia, they are associated with inhibition of motor activity and negative rewards – a feeling of discomfort in response to certain human actions. Mutations in the OPRK1 receptor gene are also associated with alcohol and opioid addiction.

"Sensitive" nociceptin

The nociceptin peptide and its receptor have been discovered recently. They act in the opposite way compared to other opioid receptors – they do not anesthetize, but on the contrary, increase sensitivity to pain. Therefore, for anesthesia, it is necessary not to stimulate the NOP receptor, but, on the contrary, to block its work. Thus, a nociceptin inhibitor can become a potential painkiller that is not addictive.

Opioid receptor agonists

The most well–known opioid receptor stimulants are morphine, heroin, codeine and loperamide. The latter is part of the remedy for diarrhea: it does not pass the blood-brain barrier, so it does not affect the brain, and its effect only affects intestinal cells.

Together with the story about opioid receptors, we end the topic of neurotransmitters. We did not have time to discuss all the active substances: for example, in the first part we missed the neurotransmitter of the monoamine group, whose excessive activity can pretty much ruin life. In order not to return to this topic, we give you homework: to find out what kind of mediator we are talking about and how it works.

Anyone who will not be lazy and will do their homework can call the Atlas clinic and use the answer as a promo code for a 10% discount on the appointment of an allergist-immunologist. It's time to do it in the fall.

Portal "Eternal youth" http://vechnayamolodost.ru  11.10.2016

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