Neurotransmitters

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton, Vidya Acharya and Kim Jackson  

Introduction[edit | edit source]

Neurotransmitters are often referred to as the body’s chemical messengers. They are the molecules used by the nervous system to transmit messages between neurones, or from neurones to muscles (eg acetylcholine, dopamine). Communication between two neurones happens in the synaptic cleft (the small gap between the synapses of neurones). Here, electrical signals that have travelled along the axon are briefly converted into chemical ones through the release of neurotransmitters, causing a specific response in the receiving neurone. At this the next neuron they are absorbed. The neurone then changes this chemical signal back into an electrical signal called an action potential. The action potential passes across the next neuron and to the next synapse.[1]

Neurotransmitters play a major role in shaping everyday life and functions. We don't know exactly how many neurotransmitters exist, but more than 100 chemical messengers have been identified and each neurotransmitter has a different function[2].

Alterations in the levels of specific neurotransmitters have been observed in various neurological disorders, including Parkinson disease, schizophrenia, depression, and Alzheimer disease[3].

Types of Neurotransmitters[edit | edit source]

A neurotransmitter influences a neuron in one of three ways: excitatory, inhibitory or modulatory.

  • An excitatory transmitter promotes the generation an action potential in the receiving neuron, while an inhibitory transmitter prevents it.
  • Modulatory Neurotransmitters can transmit messages to several cells simultaneously and also help to communicate with chemical transmitters. [1]

Function[edit | edit source]

Neurotransmitters

Neurotransmitters transmit signals from nerve cells to target cells. These target cells may be in muscles, glands, or other nerves.

The brain needs neurotransmitters to regulate many necessary functions, including: heart rate; breathing; sleep cycles; digestion; mood; concentration; appetite; muscle movement[4]

Types of Neurotransmitters[edit | edit source]

Adrenaline-ampule

There are over 50 known types of neurotransmitters. Some of the main classifications are listed below in categories:

  • Amino Acids: GABA, Glutamate.
  • Peptides: Endorphins, Oxytocin.
  • Monoamines: Dopamine, Adrenalin, Serotonin, Histamine, Norepinephrine.
  • Purines: Adenosine triphosphate, Adenosine.
  • Gasotransmitters: Carbon monoxide, Nitric oxide.
  • Acetylcholine: Acetylcholine.

Neurotransmitters and Health[edit | edit source]

Serotonin.jpeg

Alterations in the levels of specific neurotransmitters have been observed in various neurological disorders. Some are listed below.

  1. Alzheimer’s Disease: This is a neurodegenerative disorder that can be characterized by memory and learning impairments. Acetylcholine receptors are decreased in AD, and it has been shown that the reduction in the number of acetylcholine receptors precedes other pathologic changes[5].
  2. Parkinson’s Disease: Dopamine depletion, in the Substantia Nigra leads to Parkinson’s disease.
  3. Depression: There is evidence of abnormalities in noradrenergic, dopaminergic, and serotonergic transmission. Overall, serotonin has been shown to play a role in mood disorders as well as obsessive compulsive disorder (OCD).[6]
  4. Anxiety disorders: Reduced GABA activity in the brain, an imbalance of serotonin and norepinephrine responses and evidence that there may be links to increased excitability of glutamate in those with anxiety. Benzodiazepines work by reducing the excitability of nerve signals in the brain for individuals who are suffering from insomnia, anxiety and panic disorder.[6]
  5. Schizophrenia: The presence of excessive dopamine inside the frontal lobes causes schizophrenia. Patients of this severe mental disease experience psychotic episodes and they are treated by using antipsychotics drugs which work to antagonise dopamine receptors[6].
  6. Epilepsy: Patients suffer from epilepsy either because of the lack of inhibitory neurotransmitters like GABA or due to the presence of excessive excitatory neurotransmitters like glutamate[7].

[8]

Drug Effects[edit | edit source]

Heroin paraphernalia

Different types of drugs can affect the chemical transmission and change the effects of neurotransmitters. This can include medications used to alleviate the symptoms of certain mental health conditions, eg SSRIs, benzodiazepines, and anti-psychotics. Neurotransmission can also be affected by illicit drugs such as cocaine, marijuana, and heroin. eg Heroin binds to the opioid receptors and triggers the release of extremely high levels of dopamine. Tolerance will develop with use, meaning that the brain will not function the way it did before starting the drug. This can cause levels of dopamine to drop when the drug is stopped, leading to this drug being addictive so the user can feel the ‘high’ from the dopamine again.[6]

References[edit | edit source]

  1. 1.0 1.1 QBI What are neurotransmitters Available: https://qbi.uq.edu.au/brain/brain-physiology/what-are-neurotransmitters(accessed 16.4.2022)
  2. Kidzsearch Neurotransmitters Available from:https://wiki.kidzsearch.com/wiki/Neurotransmitter (accessed 23.12.2020)
  3. Sheffler ZM, Reddy V, Pillarisetty LS. Physiology, Neurotransmitters. InStatPearls [Internet] 2020 May 21. StatPearls Publishing Available from:.https://www.ncbi.nlm.nih.gov/books/NBK539894/ (accessed 23.12.2020)
  4. Very well health Neurotransmitters Available from: https://www.medicalnewstoday.com/articles/326649(accessed 23.12.2020)
  5. Kihara T, Shimohama S. Alzheimer's disease and acetylcholine receptors. Acta neurobiologiae experimentalis. 2004 Jan 1;64(1):99-106.Available: https://pubmed.ncbi.nlm.nih.gov/15190684/ (accessed 16.4.2022)
  6. 6.0 6.1 6.2 6.3 Simply Psychology neurotransmitters Available: https://www.simplypsychology.org/neurotransmitter.html (accessed 17.4.2022)
  7. Vedantu neurotransmitter Available: https://www.vedantu.com/biology/neurotransmitters (accessed 16.4.20220
  8. Whats Up DudeNeurotransmitters - What Are Neurotransmitters And What Do They Do In The Body?Available from:https://www.youtube.com/watch?v=Mz3PIvyu3ew