Neurotransmitters

Serotonin is known as an ‘inhibitory neurotransmitter’. As mentioned above, it is proven to be very active in areas involving ‘emotion & mood’ and also ‘memory’, ‘sleep/wake cycle’ & ‘body temperature regulation’ and ‘perception’. A reduction or insufficiency of Serotonin can lead to depression & suicide, obsessive-compulsive  disorder, anxiety & sleep difficulties, irritability, aggression & anger control problems. Higher levels can result in ‘elevated mood’ (such as in Bipolar Disorder), & ‘increased pain tolerance’. Serotonin is a derivative of the chemical ‘tryptophan’ which is found in milk.Exposure to ‘natural sunlight’ stimulates the release of Serotonin and the contrary applies; light deprivation can cause a depletion of Serotonin.    

Dopamine plays a major role in the ‘reward system’ and also ‘motor (voluntary movement) activity’, ‘cognition’ (thinking),’emotional responses & capacity to experience pleasure or pain’ & ‘endocrine system’. Due to its activity in reward mechanisms, one can usually presume that if it ‘feels good’, Dopamine is probably involved. Dopamine is both an ‘inhibitory’ & ‘excitatory’ neurotransmitter depending on the receptors involved. Serotonin & Dopamine tend also to counterbalance each other; if one is high, the other is usually low. Dopamine is considered a ‘relative’ of Epinephrine & Norepinephrine, being a precursor to both. Low levels of Dopamine are indicated in ‘depression’, ‘ADHD’ ‘loss of sex drive’, ‘poor attention & ability to focus’, ‘loss of satisfaction with life’, ‘addictions’, ‘cravings’, ‘decreased enthusiasm’ and in physical diseases such as ‘Parkinson’s Disease’. High levels of Dopamine are implicated in ‘Schizophrenia’, ‘psychosis’ &’psychotic symptoms’, and more recently implicated in ‘aggression’ & ‘violence’. Endorphins (mentioned later) disinhibit dopamine transmission causing more Dopamine in the synapse.  

Acetylcholine was the first neurotransmitter discovered; in 1921. It is multifunctional and both ‘inhibitory’ and ‘excitatory’ . It is responsible for much of the stimulation of muscles, particularly voluntary movement and the muscles of the gastro-intestinal tract. In the brain, its functions include ‘short-term memory’, ‘arousal’, ‘learning’, ‘reward’ and ‘sleep regulation’. Diseases such as certain ‘dementias’  indicate a serious loss of Acetylcholine. Up to 90% loss can be attributed to those suffering from ‘Alzheimer’s disease’. As an interesting and yet disturbing fact, the substance ‘Botox’ so widely used by those attempting to defy aging and rid themselves of unsightly wrinkles, is derived from the poison ‘botulin’; a deadly paralyzing poison that targets Acetylcholine receptors.  

Discovered in 1950, GABA (gamma aminobutyric acid), is primarily ‘inhibitory’. It is one of the most common neurotransmitters throughout the body and is employed in the majority of ‘fast inhibitory’ synapses in nearly every part of the brain. Because of its inhibitory nature, it is considered to be a major player in the regulation of excitatory neurotransmitters that can cause anxiety. Too little GABA and an individual may suffer from an ‘anxiety disorder’ or ‘fearfulness’, ‘insecurity’ or ‘panic’ without reason. Its low levels, or absence, are also indicated with conditions such as ‘epilepsy’ . Due to its desired effects, GABA aims to reduce ‘anxiety’, ‘panic’ & ‘pain’ while enhancing ‘calmness’ & ‘the ability to concentrate, focus & feel in control’. 

Glutamate is utilized by the body in the majority of ‘fast excitatory’ synapses in the brain & spinal cord. It is often considered to be an ‘excitatory’ relative of GABA. It is the most common neurotransmitter in the Central Nervous System (CNS) and is particularly important in ‘memory’ function. Glutamate is strangely ‘toxic’ to neurons. Too much will ‘destroy’ them. Any brain damage (such as a cerebral haemhorrage or stroke) can result in the over abundance of Glutamate and cell death much greater than from the original ‘trauma’. Curiously, Glutamate was originally extracted as an ‘acid’ from ‘seaweed’ in 1907 for the purpose of finding a ‘flavour’ common between certain food types and led to the development of ‘monosodium glutamate’ (MSG). This may explain the ‘headaches’ & ‘migraines’ experienced by those who have consumed food enhanced with MSG. 

Epinephrine or ‘adrenaline’ is essential in the ‘fight or flight’ response from the human body; bringing heightened alertness and preparedness under stress, fear, extreme pressure, anxiety, panic or other similar situations. It is considered by many to be both a ‘hormone’ secreted from the adrenal glands (located above the kidneys) & a ‘neurotransmitter’ released in certain neurons. It is primarily the hormonal effect on the body for which it is most responsible. These actions are things such as ‘increasing blood pressure’, ‘stimulating cardiac muscle’ and therefore ‘increasing heart rate’ & ‘cardiac volume’, ‘increasing release of glucose (raising blood glucose levels) & inhibiting secretion of insulin’ and ‘dilating blood vessels of major muscles (vaso-dilation)’ whilst ‘constricting peripheral blood flow(vaso-constriction)’. These actions are the physical preparations of the ‘fight or flight’ response. Its close relative ‘Norepinephrine’ is more of a major neurotransmitter type within the body and particularly significant to the Central Nervous System. 

Also known as ‘Noradrenaline’, Norepinephrine is ‘excitatory’ and is one of the ‘feel good’ neurotransmitters. Its actions involve ‘wakefulness’ & ‘arousal’, ‘blood pressure regulation’ & ‘heart rate’ and ‘memory’.  It is secreted into the blood from the adrenal glands as is ‘epinephrine’ but is also released from neurons within the nervous systems of the body when physiological changes occur in response to stressful events. Continued or heightened stress will have the effect of reducing stores of Norepinephrine, whereas exercise will tend to increase it.Norepinephrine is linked strongly with both Dopamine & Serotonin in action & effect. Dietary sources of the ‘ingredients’ for Norepinephrine production include protein substances such as meat, nuts & egg-whites. The process involves the initial digestion and metabolism into the production of Dopamine, which then is involved in the production of Norepinephrine. Serotonin is similarly produced from these essential dietary products. * As a note, ‘banana peels’ contain Norepinephrine & Dopamine in significant quantities. 

The word ‘Endorphin’ means ‘endogenous morphine’. It is the body’s self produced ‘morphine’. As such, it’s similar in action & structure to ‘opiate’ substances; ‘morphine’, ‘heroin’ & ‘opium’ etc. It is involved with ‘analgaesia or reduction of pain’, but also significant in the reward centres of the brain & the sensation of ‘pleasure’ . Opiate substances consumed from external sources will ‘lock in to’ the Endorphin receptors intended for ‘normal’ bodily functioning by internal neurotransmitters. This is effective and useful when used for ‘pain relief’; damaging & destructive when used inappropriately for ‘euphoria’. Endorphins are particularly relevant to the Rugby League player, due largely to the very nature of the sport and the resultant physical, psychological and behavioural effects. Under situations of ‘stress (psychological or physical)’, ‘excitement’, ‘pain’, ‘danger’ etc., the body releases endorphins; sometimes in high volumes and in sudden release; ‘endorphin rush’. For example, when a signal of pain is received, endorphins are released into the synapses, ‘blocking’ further pain signals or preventing continuation of ‘unpleasant’ sensations of pain. After this occurs, the individual might experience sensations or feelings of ‘power & control’ allowing them to continue their painful or stressful activities. Many would be familiar with the phrase ‘playing through the pain barrier’. The euphoric effects of endorphins are well known. The stimulation of its release through exercise has given rise to the ‘natural’ treatment & prevention of depression. It is also applicable to the ‘rush’ or excitement of ‘extreme sports’ and the capacity for greater ‘on-field’ performances. As a point of interest endorphins are also the neurotransmitters utilized by hibernating animals such as bears. Theirs is not for euphoria or pain control, but rather the slowing of essential physiology; heart rate, respirations, metabolic rate etc.