Exorphin

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Exorphins are exogenous opioid peptides, distinguished from endorphins, or endogenous opioid peptides.

Contents

Exorphins include opioid food peptides like gluten exorphin and microbial opioid peptides and any other opioid peptide foreign to a host that have metabolic efficacy for that host. [1] Exorphins can be converted from plants and animals but also dairy products and certain vegetables like spinach and soy. [2]

Exorphins can be released for many different kinds of proteins and thus can be isolated from various sources such as from plant proteins or from enzymes of the digestive system of animals. The study of exorphins as a bioactive peptide can be a source of discovery for new kinds of food and drugs to treat and prevent diseases associated with the accumulation of exorphins. [3]

Effect on central nervous system

Opioid receptors, located in both the central nervous system as well as peripheral tissues, play a vital role in regulating numerous physiological functions. Many of these functions are influenced by exorphins. To impact the central nervous system, exorphins bind to opioid receptors, thereby regulating neuronal communication. This binding affects pain perception, emotions, mood, memory, and more. The influence of exorphins on brain function suggests that exogenous opioid peptides may cross the blood-brain barrier. This understanding of how endorphins enter through blood and end up affecting brain functions could pave the way for the development of new treatment strategies. [4]

Effect on gastrointestinal system

Aside from the central nervous system, exorphins also affect the gastrointestinal system. As mentioned earlier, exorphins are peptides that are derived from food. There are different types of exorphins such as gluten exorphins (gluten), casomorphins (milk), and many other types of exorphins from various sources. Depending on the type of source, they hold a different effect upon the body--some foods affect functions such as appetite, release of hormones, production of mucus, and more. For instance, casomorphins regulate motility, secretion of hormones, and immune responses. [5]

Connection and treatment of autism

Effective therapies to manage autism remain scarce. According to the exorphin theory of autism, an increase in the levels of exorphin is linked to symptoms of autism. Based on this concept, experiments have attempted to reduce the symptoms of autism by using large amounts of protease to break down exorphins before they are absorbed. Experiments have also attempted to enhance and utilize enzymes existing in the gut to break down exorphins in a similar fashion, since the production of exorphins within the gut is inevitable. [6]

Connection with schizophrenia

Exorphins can cause various symptoms of schizophrenia if mutation occurs at a few selected loci. Genetic mutation at one of these loci can lead to increased absorption of exorphins via receptor mediated endocytosis. Another possibility from these particular loci is that catabolization of exorphins can be disrupted thus allowing the exorphin to persist in the body. This would lead to exorphins entering the brain capillary, bypassing the blood brain barrier, and inflicting negative repercussion on the brain. This does not mean that exorphin will necessarily cause schizophrenia, as susceptibility to the disease is dependent on an individual's genetic makeup. [7] However, by increasing the probability that exorphins enter the brain, it will also increase the chance of an individual displaying schizophrenic symptoms.

Connection with celiac disease

Celiac disease (CD) is a chronic autoimmune disorder that damages the small intestine. In turn, the body is unable to absorb nutrients from food. The gastrointestinal issues that usually come along with CD includes abdominal pain, bloating, as well as other symptoms. When patients do not show any symptoms but are affected by CD, they have asymptomatic celiac disease (ACD). According to research, there are links between an intake in gluten and ACD. The intake in gluten results in more exorphins in the body, which results in ACD. Often, patients with ACD also have other disorders such as diabetes mellitus I, autism, schizophrenia, depression, and several others. This indicates that there is a high chance that the other disorders are also associated with the increase of gluten exorphins. [8]

Related Research Articles

<span class="mw-page-title-main">Gluten</span> Group of cereal grain proteins

Gluten is a structural protein naturally found in certain cereal grains. The term gluten usually refers to the elastic network of a wheat grain's proteins, gliadin and glutenin primarily, that forms readily with the addition of water and often kneading in the case of bread dough. The types of grains that contain gluten include all species of wheat, and barley, rye, and some cultivars of oat; moreover, cross hybrids of any of these cereal grains also contain gluten, e.g. triticale. Gluten makes up 75–85% of the total protein in bread wheat.

<span class="mw-page-title-main">Neurotransmitter</span> Chemical substance that enables neurotransmission

A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, or target cell, may be another neuron, but could also be a gland or muscle cell.

<span class="mw-page-title-main">Endorphins</span> Hormones and neuropeptides

Endorphins are peptides produced in the brain that block the perception of pain and increase feelings of wellbeing. They are produced and stored in the pituitary gland of the brain. Endorphins are endogenous painkillers often produced in the brain and adrenal medulla during physical exercise or orgasm and inhibit pain, muscle cramps, and relieve stress.

<span class="mw-page-title-main">Coeliac disease</span> Autoimmune disorder that results in a reaction to gluten

Coeliac disease or celiac disease is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barley. Classic symptoms include gastrointestinal problems such as chronic diarrhoea, abdominal distention, malabsorption, loss of appetite, and among children failure to grow normally.

A gluten-free casein-free diet, also known as a gluten-free dairy-free diet, is a diet that does not include gluten, and casein. Despite an absence of scientific evidence, there have been advocates for the use of this diet as a treatment for autism and related conditions.

<span class="mw-page-title-main">Histamine</span> Organic compound involved in immune responses

Histamine is an organic nitrogenous compound involved in local immune responses communication, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Discovered in 1910, histamine has been considered a local hormone (autocoid) because it's produced without involvement of the classic endocrine glands; however, in recent years, histamine has been recognized as a central neurotransmitter. Histamine is involved in the inflammatory response and has a central role as a mediator of itching. As part of an immune response to foreign pathogens, histamine is produced by basophils and by mast cells found in nearby connective tissues. Histamine increases the permeability of the capillaries to white blood cells and some proteins, to allow them to engage pathogens in the infected tissues. It consists of an imidazole ring attached to an ethylamine chain; under physiological conditions, the amino group of the side-chain is protonated.

<span class="mw-page-title-main">Gluten-free diet</span> Diet excluding proteins found in wheat, barley, and rye

A gluten-free diet (GFD) is a nutritional plan that strictly excludes gluten, which is a mixture of prolamin proteins found in wheat, as well as barley, rye, and oats. The inclusion of oats in a gluten-free diet remains controversial, and may depend on the oat cultivar and the frequent cross-contamination with other gluten-containing cereals.

<span class="mw-page-title-main">Casomorphin</span> Chemical compound

Casomorphin is an opioid peptide derived from the digestion of the milk protein casein.

β-Endorphin Peptide hormone in humans

β-Endorphin (beta-endorphin) is an endogenous opioid neuropeptide and peptide hormone that is produced in certain neurons within the central nervous system and peripheral nervous system. It is one of three endorphins that are produced in humans, the others of which include α-endorphin and γ-endorphin.

Gluten exorphins are a group of opioid peptides formed during the digestion of the gluten protein. These peptides work as external regulators for gastrointestinal movement and hormonal release. The breakdown of gliadin, a polymer of wheat proteins, creates amino acids that stop the gluten epitopes from entering the immune system to activate inflammatory reactions. During this process, gluten does not fully break down, thus increasing the presence of gluten exorphins. Because of this, researchers think this is what might lead to various diseases.

<span class="mw-page-title-main">Gliadin</span> Protein in wheat & other cereals

Gliadin is a class of proteins present in wheat and several other cereals within the grass genus Triticum. Gliadins, which are a component of gluten, are essential for giving bread the ability to rise properly during baking. Gliadins and glutenins are the two main components of the gluten fraction of the wheat seed. This gluten is found in products such as wheat flour. Gluten is split about evenly between the gliadins and glutenins, although there are variations found in different sources.

<span class="mw-page-title-main">Opioid peptide</span> Class of peptides that bind to opioid receptors

Opioid peptides or opiate peptides are peptides that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Such peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but they all resemble those of opiates. Brain opioid peptide systems are known to play an important role in motivation, emotion, attachment behaviour, the response to stress and pain, control of food intake, and the rewarding effects of alcohol and nicotine.

Intestinal permeability is a term describing the control of material passing from inside the gastrointestinal tract through the cells lining the gut wall, into the rest of the body. The intestine normally exhibits some permeability, which allows nutrients to pass through the gut, while also maintaining a barrier function to keep potentially harmful substances from leaving the intestine and migrating to the body more widely. In a healthy human intestine, small particles can migrate through tight junction claudin pore pathways, and particles up to 10–15 Å can transit through the paracellular space uptake route. There is some evidence abnormally increased intestinal permeability may play a role in some chronic diseases and inflammatory conditions. The most well understood condition with observed increased intestinal permeability is celiac disease.

<span class="mw-page-title-main">Vomiting</span> Involuntary, forceful expulsion of stomach contents, typically via the mouth

Vomiting is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose.

<span class="mw-page-title-main">Prolyl endopeptidase</span>

Prolyl endopeptidase (PE) also known as prolyl oligopeptidase or post-proline cleaving enzyme is an enzyme that in humans is encoded by the PREP gene.

<i>N</i>-Acetylaspartylglutamic acid Peptide neurotransmitter

N-Acetylaspartylglutamic acid is a peptide neurotransmitter and the third-most-prevalent neurotransmitter in the mammalian nervous system. NAAG consists of N-acetylaspartic acid (NAA) and glutamic acid coupled via a peptide bond.

<span class="mw-page-title-main">Gluten-related disorders</span> Set of diseases caused by gluten exposure

Gluten-related disorders is the term for the diseases triggered by gluten, including celiac disease (CD), non-celiac gluten sensitivity (NCGS), gluten ataxia, dermatitis herpetiformis (DH) and wheat allergy. The umbrella category has also been referred to as gluten intolerance, though a multi-disciplinary physician-led study, based in part on the 2011 International Coeliac Disease Symposium, concluded that the use of this term should be avoided due to a lack of specificity.

FODMAPs or fermentable oligosaccharides, disaccharides, monosaccharides, and polyols are short-chain carbohydrates that are poorly absorbed in the small intestine and ferment in the colon. They include short-chain oligosaccharide polymers of fructose (fructans) and galactooligosaccharides, disaccharides (lactose), monosaccharides (fructose), and sugar alcohols (polyols), such as sorbitol, mannitol, xylitol, and maltitol. Most FODMAPs are naturally present in food and the human diet, but the polyols may be added artificially in commercially prepared foods and beverages.

The opioid excess theory is a theory which postulates that autism is the result of a metabolic disorder in which opioid peptides produced through metabolism of gluten and casein pass through an abnormally permeable intestinal membrane and then proceed to exert an effect on neurotransmission through binding with opioid receptors. It is believed by advocates of this hypothesis that autistic children are unusually sensitive to gluten, which results in small bowel inflammation in these children, which in turn allows these opioid peptides to enter the brain.

Non-celiac gluten sensitivity (NCGS) or gluten sensitivity is a controversial disorder which can cause both gastrointestinal and other problems.

References

  1. ↑ Pruimboom L, de Punder K (November 2015). "The opioid effects of gluten exorphins: asymptomatic celiac disease". Journal of Health, Population, and Nutrition. 33 (1): 24. doi: 10.1186/s41043-015-0032-y . PMC   5025969 . PMID   26825414.
  2. ↑ Teschemacher H (2003-06-01). "Opioid receptor ligands derived from food proteins". Current Pharmaceutical Design. 9 (16): 1331–44. doi:10.2174/1381612033454856. PMID   12769741.
  3. ↑ Yoshikawa M (2013). "Chapter 214: Exorphins". In Kastin AJ (ed.). Handbook of Biologically Active Peptides (2nd ed.). Academic Press. pp. 1570–1576. ISBN   978-0-12-385096-6.
  4. ↑ Liu, Z., & Udenigwe, C. C. (2019). "Role of food-derived opioid peptides in the central nervous and gastrointestinal systems". Journal of Food Biochemistry. 43 (1): e12629. doi:10.1111/jfbc.12629. PMID   31353498.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ↑ Tyagi, A., Daliri, E. B. -M., Kwami Ofosu, F., Yeon, S. -J., & Oh, D. -H. (2020). "Food-Derived Opioid Peptides in Human Health: A Review". International Journal of Molecular Sciences. 21 (22): 8825. doi: 10.3390/ijms21228825 .{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ↑ Brudnak MA, Rimland B, Kerry RE, Dailey M, Taylor R, Stayton B, et al. (May 2002). "Enzyme-based therapy for autism spectrum disorders -- is it worth another look?". Medical Hypotheses. 58 (5): 422–8. doi:10.1054/mehy.2001.1513. PMID   12056881.
  7. ↑ Dohan FC (1988-01-01). "Genetic hypothesis of idiopathic schizophrenia: its exorphin connection". Schizophrenia Bulletin. 14 (4): 489–94. doi: 10.1093/schbul/14.4.489 . PMID   2851166.
  8. ↑ Pruimboom, L., de Punder, K. (2015). "The opioid effects of gluten exorphins: asymptomatic celiac disease". J Health Popul Nutr. 33: 24. doi: 10.1186/s41043-015-0032-y . PMID   26825414.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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