Definition of a Neurotransmitter
Neurotransmitters are types of hormones in the brain that transmit information from one neuron to another. They are made by amino acids. Neurotransmitters control major body functions including movement, emotional response, and the physical ability to experience pleasure and pain. The most familiar neurotransmitters which are thought to play a role in mood regulation are serotonin, norepinephrine, dopamine, acetylcholine, and GABA.
Neurotransmitter Effects on Mental Health:
- Modulate mood and thought processes
- Control ability to focus, concentrate, and remember things
- Control the appetite center of the brain
- Regulate sleep
Types of Neurotransmitters
Neurotransmitters can be broadly classified into two categories; excitatory and inhibitory. Some neurotransmitters can serve both functions.
Excitatory neurotransmitters are the nervous system’s “on switches”, increasing the likelihood that an excitatory signal is sent. They act like a car’s accelerator, revving up the engine. Excitatory transmitters regulate many of the body’s most basic functions including: thought processes, the body’s fight or flight response, motor movement and higher thinking. Physiologically, the excitatory transmitters act as the body’s natural stimulants, generally serving to promote alertness, energy, and activity. Without a functioning inhibitory system to put on the brakes, things can get out of control.
Inhibitory neurotransmitters are the nervous system’s “off switches”, decreasing the likelihood that an excitatory signal is sent. Excitation in the brain must be balanced with inhibition. Too much excitation can lead to restlessness, irritability, insomnia, and even seizures. Inhibitory transmitters regulate the activity of the excitatory neurotransmitters, much like the brakes on a car. The inhibitory system slows things down. Physiologically, the inhibitory transmitters act as the body’s natural tranquilizers, generally serving to induce sleep, promote calmness, and decrease aggression.
- Acetylchlorine helps with memory and learning.
- Dopamine is primarily responsible for sex drive, mood, alertness, and movement.
- Norepinephrine and epinephrine influence alertness, arousal, and mood.
- Serotonin is involved in mood, appetite control, emotional balance, and impulse control.
- GABA helps with relaxation and sedation.
Acetylcholine release can be excitatory or inhibitory depending on the type of tissue and the nature of the receptor with which it interacts. Acetylcholine plays numerous roles in the nervous system. Its primary action is to stimulate the skeletal muscular system. It is the neurotransmitter used to cause voluntary muscle contraction or relaxation in the muscles.
In the brain, acetylcholine is involved in learning and memory. Acetylcholine is a small molecule transmitter that is also found in the hippocampus and prefrontal cortex. The hippocampus is responsible for memory and memory retrieval. Alzheimer’s disease is associated with a lack of acetylcholine in certain regions of the brain.
Dopamine can act as both an excitatory or inhibitory neurotransmitter and functions as the brain’s “feel good” neurotransmitter. It is part of the brain’s reward system and creates feelings of satisfaction or pleasure when we do things we enjoy, such as eating or having sex. Drugs like cocaine, nicotine, opiates, heroin, and alcohol increase the levels of dopamine. Eating foods that taste good and having sex also stimulate an increase in dopamine levels. For this reason, many surmise that a deficient level of dopamine in the brain may be behind peoples’ tendencies to use drugs, drink alcohol, smoke cigarettes, be promiscuous, gamble or overeat.
Dopamine’s functions are diverse, affecting memory, motor control, and pleasure. It allows us to be alert and motivated and to feel satisfied. Dopamine is associated with positive stress states such as being in love, exercising, listening to music, and sex. Once produced, dopamine can, in turn, convert into the brain chemicals norepinephrine and epinephrine.
However, too much of a good thing can be bad for you. An increased level of dopamine in the frontal lobe of the brain contributes to the incoherent and disrupted thought processes that are characteristic of schizophrenia. Excessive levels of dopamine cause our thinking to become excited, energized, then suspicious and paranoid as we are hyperstimulated by our environment. With low levels of dopamine we lose the ability to focus. When dopamine levels are too high our focus becomes narrowed and intense. High dopamine levels have been observed in patients with poor gastrointestinal function, autism, mood swings, aggression, psychosis, anxiety, hyperactivity, and children with attention disorders.
Too little dopamine in the motor areas of the brain are responsible for Parkinson’s disease, which involves uncontrollable muscle tremors. A decline in dopamine levels in the thinking areas of the brain is linked to cognitive problems (learning and memory deficits), poor concentration, difficulty initiating or completing tasks, impaired ability to “lock onto” tasks, activities, or conversations, lack of energy, lack of motivation, inability to “feel alive”, addictions, cravings, compulsions, a loss of satisfaction in activities which previously pleased you, and slowed motor movements.
Epinephrine, also known as adrenaline, is an excitatory neurotransmitter. It is derived from norepinephrine and is secreted along with norepinephrine in response to fear or anger. This reaction, referred to as the “fight or flight” response, prepares the body for strenuous activity. Epinephrine regulates attentiveness, arousal, cognition, sexual arousal, and mental focus. It is also responsible for regulating the metabolism. Epinephrine is used medicinally as a stimulant in cardiac arrest, as a vasoconstrictor in shock, as a bronchodilator and antispasmodic in bronchial asthma, and anaphylaxis.
Epinephrine levels which are too high can result in restlessness, anxiety, sleep problems, acute stress, and ADHD. Excess amounts of epinephrine can also raise the blood pressure, increase the heart rate, cause irritability and insomnia.
Low levels of epinephrine can also contribute to weight gain, fatigue, lack of focus, decreased sexual arousal, and poor concentration.
Stress tends to deplete our store of adrenalin (epinephrine), while exercise tends to increase it.
GABA is the abbreviation for Gamma-aminobutyric acid. GABA is the major inhibitory neurotransmitter in the central nervous system and plays a major role in regulating anxiety and reducing stress. GABA has a calming effect on the brain and helps the brain filter out “background noise”. It improves mental focus while calming the nerves. GABA acts like a brake to the excitatory neurotransmitters which can cause anxiety if the system is overstimulated. It regulates norepinephrine, adrenaline, dopamine, and serotonin and is a significant mood modulator. The primary function of GABA is to prevent overstimulation.
Excessive GABA levels result in excessive relaxation and sedation, to the point that normal reactions are impaired.
Insufficient GABA results in the brain being overstimulated. People with too little GABA tend to suffer from anxiety disorders and may have a predisposition to alcoholism. Low levels of GABA are associated with bipolar disorder, mania, poor impulse control, epilepsy, and seizure disorders. Since proper GABA functioning is required to induce relaxation, analgesia, and sleep, dysfunction of the GABA system is implicated in the pathophysiology of several neuropsychiatric disorders, including anxiety and depression. In 1990, a study linked lowered levels of GABA to a predisposition to alcoholism. When men of alcoholic fathers with low GABA drank a glass of vodka their GABA levels rose to the equivalent of the control group.
Glutamate is a major excitatory neurotransmitter that is associated with learning and memory. It is also thought to be associated with Alzheimer’s disease. Glutamate has been implicated in epileptic seizures and is a key molecule in cellular metabolism. It is also one of the major food components that provides flavor. Glutamate is found in all protein-containing foods such as cheese, milk, mushrooms, meat, fish, and many vegetables. Monosodium glutamate is a sodium salt of glutamate.
Excessive levels of glutamate are toxic to neurons and have been implicated in the development of neurological disorders such as amyotrophic lateral sclerosis and Huntington’s chorea, peripheral neuropathies, chronic pain, schizophrenia, stroke, and Parkinson’s disease.
Insufficient levels of glutamate may play a role in impaired memory and learning.
Histamine is most commonly known for its role in allergic reactions but it is also involved in neurotransmission and can affect your emotions and behavior as well. Histamine helps control the sleep-wake cycle and promotes the release of epinephrine and norepinephrine.
High histamine levels have been linked to obsessive compulsive tendencies, depression, and headaches.
Low histamine levels can contribute to paranoia, low libido, fatigue, and medication sensitivities.
MonoaminesThis is a class of neurotransmitters which includes serotonin, norepinephrine, GABA, glutamate, and dopamine. The monoamine hypothesis holds that mood disorders are caused by depletion in the levels of one or more of these neurotransmitters.
Norepinephrine is an excitatory neurotransmitter that is important for attention and focus. Norepinephrine is synthesized from dopamine and is strongly associated with bringing our nervous systems into the “fight or flight” state. Norepinephrine triggers the release of hormones from the limbic section of the brain that signal other stress hormones to act in a crisis. It can raise blood pressure and increase heart rate. It can elevate the metabolic rate, body temperature and stimulate the smooth bronchial muscles to assist breathing. It is also important for forming memories.
Elevated norepinephrine activity seems to be a contributor to anxiety. Also, brain norepinephrine turnover is increased in conditions of stress. Increased levels of norepinephrine will lead to alertness and mood elevation and increased sexual interest. However, high amounts raise blood pressure, increase heart rate, and cause anxiety, fear, panic, stress, hyperactivity, an overwhelming sense of dread, irritability, and insomnia.
Low levels of norepinephrine are linked to lack of energy, focus, and motivation. Insufficient norepinephrine levels also contribute to depression, loss of alertness, and poor memory.
PEA is an excitatory neurotransmitter made from phenylalanine. It is important in focus and concentration.
Elevated PEA levels are observed in individuals experiencing “mind racing”, sleep problems, anxiety, and schizophrenia.
Low PEA is associated with difficulty paying attention or thinking clearly, and in depression
Serotonin is an inhibitory neurotransmitter involved in the regulation of mood, anxiety, libido, compulsivity, headaches, aggression, body temperature, eating disorders, social anxiety, phobias, sleep, appetite, memory and learning, cardiovascular function, muscle contraction, and endocrine regulation. Other brain neurotransmitters, such as dopamine and norepinephrine, also influence mood and arousal. However, serotonin generally has different effects.
Serotonin plays a major role in sleep and mood regulation. Proper amounts of circulating serotonin promote relaxation. Stress reduces our serotonin levels as our body uses up serotonin in an attempt to calm itself.
Low levels of serotonin can result in depressed mood, anxiety, panic attacks, low energy, migraines, sleeping problems, obsessions or compulsions, feeling tense and irritable, craving sweets or loss of appetite, impaired memory and concentration, angry or aggressive behavior, slowed muscle movement, slowed speech, altered sleep patterns, and having a reduced interest in sex.
Excess amounts of serotonin cause sedation, a decrease in sexual drive, a sense of well-being, bliss, and of being one with the universe. However, if serotonin levels become too high they can result in Serotonin Syndrome, which can be fatal.
Extremely high levels of serotonin can be toxic and possibly fatal, causing a condition known as “Serotonin Syndrome”. It is very difficult to reach these high levels by overdosing on a single antidepressant, but combining different agents known to increase levels of Serotonin, such as an SSRI and an MAOI, can result in this condition. Taking recreational Ecstasy can also have this effect, but rarely leads to toxicity. Serotonin Syndrome produces violent trembling, profuse sweating, insomnia, nausea, teeth chattering, chilling, shivering, aggressiveness, over-confidence, agitation, and malignant hyperthermia. Emergency medical treatment is required, utilizing medications that neutralize or block the action of serotonin.
Factors affecting serotonin production
Your hormones and Estrogen levels can affect serotonin levels and this may explain why some women have pre-menstrual and menopausal mood problems. Moreover, daily stress can greatly reduce your serotonin supplies.
While exercise and exposure to light may increase or stimulate serotonin levels, antidepressants can aid the brain to replenish its own supply. The most recent SSRI antidepressants, (selective serotonin reuptake inhibitors) are current drugs of choice to increase serotonin circulation.
Taurine is an inhibitory neurotransmitter involved in neuromodulatory and neuroprotective actions. Supplementing with taurine can increase GABA function. By helping GABA function, taurine is an important neuromodulator for prevention of anxiety. The relevance of GABA support is to prevent overstimulation due to high levels of excitatory amino acids, such as norepinephrine and epinephrine. Therefore, taurine and GABA constitute an important protective mechanism against excessive excitatory neurotransmitters.