An image showing the inner workings of the brain, and chemicals representing neirotransmitters floating around it. to illustrate and article about neurotransmitters on

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Biological neurotransmitters

neurotransmitters are chemical messengers that facilitate communication between nerve cells, or neurons. They play a vital role in modulating and balancing neural signals, thereby maintaining brain function. They regulate autonomic responses like breathing and heart rate and psychological functions such as learning, mood, fear, pleasure, and happiness (Simply Psychology, 2023). neurotransmitters are released from synaptic vesicles of the presynaptic neuron and travel across a tiny gap called a synapse to bind to specialised receptor sites on the postsynaptic neuron. This process is known as neurotransmission (Study Rocket, n.d.). There are different types of neurotransmitters, such as serotonin, dopamine, and norepinephrine, among others. Each neurotransmitter has a specific function and effect on the target cell. Some neurotransmitters have an inhibitory effect, making neurons less likely to fire, thus promoting calmness and sleep. Others have an excitatory effect, increasing the likelihood of neuron firing and elevating alertness or arousal (Medical News Today, 2024). neurotransmitters are essential for neural signaling and brain activity, and their imbalance or dysfunction can lead to various disorders, such as depression, anxiety, schizophrenia, Parkinson’s disease, and Alzheimer’s disease.

adrenaline and noradrenaline

adrenaline and noradrenaline are two related hormones and neurotransmitters that play important roles in the body’s response to stress or danger. They belong to a group of chemicals called catecholamines, which are produced in the adrenal glands and some nerve cells (You and Your hormones, n.d.). adrenaline, also known as epinephrine, is mainly secreted by the adrenal medulla, which is the inner part of the adrenal gland. It acts on both alpha and beta adrenergic receptors, which are found in various tissues and organs. Some of the effects of adrenaline include increasing heart rate, blood pressure, blood sugar, and oxygen intake, as well as dilating the airways and reducing pain sensation (WebMD, 2023). adrenaline is also used as a medication to treat severe allergic reactions or anaphylaxis (WebMD, 2023).

noradrenaline, also known as norepinephrine, is secreted by both the adrenal medulla and the postganglionic neurons of the sympathetic nervous system, which is the part of the nervous system that prepares the body for action. It acts mainly on beta adrenergic receptors, but also on some alpha receptors. Some of the effects of noradrenaline include increasing heart rate, blood pressure, and blood flow to the muscles and brain, as well as constricting blood vessels and increasing alertness and focus (Pediaa.Com, 2018). noradrenaline is also used as a medication to raise blood pressure in cases of shock or low blood pressure (Pediaa.Com, 2018).


serotonin is a neurotransmitter that plays a key role in various aspects of brain function, such as mood, cognition, emotion, and behaviour. It is synthesized from the amino acid tryptophan and is mainly found in the brain, the gastrointestinal tract, and the blood platelets. It acts on different types of receptors in the brain, which have diverse effects on neuronal activity and plasticity. Some of the most studied serotonin receptors are the 5-HT1A and 5-HT2A receptors, which are involved in regulating stress responses, learning, memory, and perception (Carhart-Harris & Nutt, 2017). serotonin also modulates other neurotransmitter systems, such as dopamine, glutamate, and GABA, and influences various physiological processes, such as sleep, appetite, pain, and thermoregulation. serotonin levels are affected by genetic factors, environmental factors, diet, drugs, and diseases. Altered serotonin function has been implicated in various psychiatric disorders, such as depression, anxiety, schizophrenia, and autism. Several pharmacological treatments for these disorders target the serotonin system, such as selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors (MAOIs), and psychedelics (Müller & Jacobs, 2010).

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endorphins are a group of neuropeptides that act as natural painkillers in the body. They are produced by the pituitary gland and the hypothalamus in response to stress, pain, or positive emotions (APA Dictionary of Psychology, n.d.). endorphins bind to opioid receptors in the brain and spinal cord, inhibiting the transmission of pain signals and producing a sense of euphoria, relaxation, or well-being. endorphins also modulate other neurotransmitter systems, such as dopamine, serotonin, and norepinephrine, which are involved in mood, motivation, and reward (Dishman & O’Connor, 2009). They have been implicated in various behavioural phenomena, such as exercise-induced analgesia, runner’s high, social bonding, maternal behaviour, and learning and memory (Koob & Bloom, 1982).

Gamma-aminobutyric acid

Gamma-aminobutyric acid (GABA) is a neurotransmitter, a chemical messenger that carries signals between nerve cells in the brain and the central nervous system (CNS) (Cleveland Clinic, 2023). GABA is the most abundant inhibitory neurotransmitter in the CNS, meaning that it reduces the activity of the neurons that it binds to, creating a calming effect (Verywell Health, 2023). GABA is involved in regulating mood, anxiety, stress, sleep, and various neurological and psychiatric disorders (Healthline, 2023). It works by attaching to specific receptors on the surface of the nerve cells, called GABA-A and GABA-B receptors, and triggering a series of reactions that make the cells less responsive to incoming signals (Cleveland Clinic, 2023). GABA also interacts with other neurotransmitters, such as glutamate and serotonin, to maintain a balance between inhibition and excitation in the brain (Everyday Health, 2023).

Threats to neurotransmission

neurotransmitters can be impacted by various factors, including poor diet, sensory overload, and genetics.

A poor diet can affect the production and balance of neurotransmitters by depriving the body of essential nutrients that are needed as precursors or cofactors for their synthesis. For example, tryptophan is an amino acid that is converted into serotonin, a neurotransmitter that regulates mood, sleep, and appetite. Tryptophan is found in foods such as eggs, cheese, turkey, nuts, and seeds. A lack of tryptophan can lead to low serotonin levels and an increased risk of depression, anxiety, insomnia, and obesity (Gasmi et al., 2023). Similarly, tyrosine is another amino acid that is converted into dopamine, a neurotransmitter that controls reward, motivation, and movement. Tyrosine is found in foods such as meat, fish, dairy, soy, and bananas. A deficiency of tyrosine can result in low dopamine levels and impaired cognitive function, motor skills, and emotional regulation (Gasmi et al., 2023).

Sensory overload can also affect the activity and balance of neurotransmitters by overstimulating or inhibiting certain receptors in the brain. For instance, glutamate is a neurotransmitter that acts as an excitatory signal for learning and memory. However, too much glutamate can cause excitotoxicity, a process that damages or kills neurons by over-activating them. This can lead to symptoms such as anxiety or sensory overload (Dhailappan & Samiappan, 2022). On the other hand, GABA is a neurotransmitter that acts as an inhibitory signal for relaxation and calmness. However, too little GABA can cause hyperactivity, restlessness, and stress (Dhailappan & Samiappan, 2022).

Genetics can also influence the levels and function of neurotransmitters by affecting the expression and activity of enzymes, transporters, receptors, and other molecules involved in their synthesis, release, uptake, degradation, and signalling. For example, some genetic variants can affect the activity of monoamine oxidase (MAO), an enzyme that breaks down serotonin, dopamine, and norepinephrine. Depending on the variant, MAO activity can be either increased or decreased, leading to either lower or higher levels of these neurotransmitters in the brain (Harvard Health Publishing, 2015). Similarly, some genetic variants can affect the sensitivity or number of receptors for certain neurotransmitters on the surface of neurons. This can alter the response or feedback of these neurons to the neurotransmitter signals (Harvard Health Publishing, 2015).

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Other factors that affect neurotransmitters include stress, diet, drugs, and toxins can alter the levels or functions of neurotransmitters in the brain and the gut (Yang et al., 2021). The gut-brain axis is a bidirectional communication system that involves the enteric nervous system (ENS), which is a network of nerve cells in the digestive tract that can produce and respond to neurotransmitters. The ENS can influence mood, cognition, and behaviour through its interactions with the central nervous system (CNS) (Johns Hopkins Medicine, n.d.). Moreover, neurotransmitters play a role in the pathophysiology of various immune-mediated inflammatory diseases, such as multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, Alzheimer’s disease, and Parkinson’s disease. These diseases may involve dysregulation of neurotransmitter signalling or receptors in the immune system, leading to inflammation and tissue damage (Ghosh et al., 2022).

In conclusion, neurotransmitters are important molecules that mediate communication between neurons and other cells in the body. They are involved in various physiological and psychological processes that affect our health and wellbeing. However, they can be impacted by various factors such as poor diet, sensory overload, and genetics. Therefore, it is important to maintain a balanced and nutritious diet that provides adequate amounts of amino acids, vitamins, minerals, antioxidants, and other nutrients that support neurotransmitter production and function. It is also important to avoid excessive or prolonged exposure to stressful or stimulating stimuli that can disrupt neurotransmitter balance and cause neuronal damage. Moreover, it is important to be aware of one’s genetic predispositions that can affect neurotransmitter levels and activity and seek appropriate medical advice if needed.


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