Dopamine is a neurotransmitter that is produced and released by nerve cells in the brain and spinal cord. It is responsible for energy, well-being, and motivates to action. Check what affects the level of dopamine and how to supplement its deficiency?
Dopamineis an organic chemical compound that performs many different functions in the human body, depending on where it is active.
It affects, among other things, blood pressure, the regulation of muscle tone, the work of endocrine glands, and even the feeling of emotions.
Together with adrenaline and norepinephrine, they are the main catecholamines produced by the adrenal medulla.
Dopamine also plays a significant role in the human endocrine system, especially the regulation of prolactin secretion by the pituitary gland, and is an important neurotransmitter, mainly in the extrapyramidal nervous system.
Changes in the activity and the number of dopamine neurons in the brain can lead to many serious neurological diseases such as Parkinson's disease, chorea or schizophrenia, mental disorders with productive symptoms, addiction and hormonal disorders.
Dopamine - role in the nervous system
The main neurotransmitters in the human nervous system include acetylcholine, serotonin, dopamine and norepinephrine.
They are produced in the bodies of neurons, which group together in different parts of the brain and send relevant information to the cerebral cortex and spinal cord.
Dopamine is the main neurotransmitter in the following components of the human nervous system:
- extrapyramidal nervous system
The largest cluster of dopamine neurons is found in the substantia nigra in the midbrain, which is part of the extrapyramidal nervous system. It is responsible for triggering free movements and regulating the tension of skeletal muscles.
Patients with disorders of this component of the nervous system complain of pathological changes in muscle tone (stiffness in parkinsonism, decreased tension in chorea), the occurrence of involuntary movements (rest tremor in parkinsonism, choreic, athetotic, ballistic, dystonic movements) and difficulties in coordinating movements.
- limbic system
A smaller cluster of neurons whose neurotransmitter is dopamine is found in the tegmental area of the midbrain. From here, nerve impulses are sent to the structures of the limbic system, responsible for the regulation of human emotional behavior and the processes of remembering.
It has been proven that dopamine is involved in the action of the so-called reward system, and the activity of dopamine neurons increases while waiting for activities that give you pleasure, such as entertainment, shopping, gambling or eating.
For this reason, many scientists colloquially call dopamine the neurotransmitter of happiness, and disturbances in the activity of neurons in which dopamine is the neurotransmitter are the basis of drug addiction and addiction to psychoactive factors.
- pituitary gland
Another cluster of dopamine neurons is found in the nuclei of the hypothalamus and is responsible for transmitting signals to the pituitary gland. This is closely related to the regulation of the production of the prolactin hormone, the synthesis of which is inhibited by dopamine.
Dopamine hypothesis of schizophrenia
Schizophrenia is a chronic disease that belongs to the group of psychotic disorders. In Polish society, 1% of the population struggles with this disease, and women and men suffer from the disease equally often.
A characteristic feature of people suffering from schizophrenia is inadequate and uncritical assessment of themselves, their surroundings and the situation.
Schizophrenics often think, do and feel differently, they are lost and begin to isolate themselves from the outside world.
The first symptoms of the disease appear most often in young people, especially those under the age of 30.
Many scientists argue that the underlying cause of schizophrenia is an overactive dopaminergic neurotransmitter in the human central nervous system.
It is for this reason that pharmacological treatment of the disease is based on administering neuroleptics to patients.
These are antipsychotic drugs whose action is mainly related to the blocking of dopaminergic receptors in the central nervous system.
Dopamine deficiency and Parkinson's disease
Parkinson's disease is a degenerative disease of the central nervous system. The cause of its occurrence has not been clearly known, it is presumed that it has a genetic background.
It has been proven that degenerative changes in the cells of the substantia nigra of the midbrain are at the root of the disease.
Neurons that make up this element of the brain produce dopamine, it is its deficiency that is responsible for the symptoms of the extrapyramidal systemnervous disorders in patients.
It is worth mentioning that the dopamine system has a remarkable ability to compensate for the loss of nerve cells.
The symptoms of Parkinsonism do not appear until 80% of neurons have died, and the rest of them are no longer able to secrete the right amount of the neurotransmitter.
The characteristic symptoms of Parkinson's disease include impaired coordination of voluntary movements, problems with maintaining balance, slowness of movement, muscle stiffness, abnormal writing, slurred speech and typical tremor while resting.
Treatment of patients is based on increasing the concentration of dopamine through its substitution and inhibiting its breakdown with the use of specialized drugs.
Excess dopamine and chorea
Chorea is a disease of the central nervous system that can be caused by a primary nervous system disease, trauma, the use of certain medications, or exposure to toxic substances and their effect on specific brain structures.
Chorea is characterized by uncoordinated body movements that resemble dancing.
The patient suffers from reduced skeletal muscle tension, complains of bothersome tremors in the upper and lower limbs, and the occurrence of involuntary movements.
It is believed that the cause of such disorders in the extrapyramidal nervous system is the excessive activity of neurons in which dopamine is the neurotransmitter.
Treatment of patients is therefore based on blocking dopaminergic receptors in the central nervous system through the use of specialized drugs.
Dopamine and addiction
Scientists believe that the underlying neurobiological mechanisms of addiction lie in disturbances in the activity of dopaminergic neurons in the central nervous system, which form the reward system.
Psychoactive substances such as alcohol, nicotine, cannabinoids, cocaine and amphetamines increase the amount of dopamine released from neuron endings and thus stimulate the mesolimbic reward system.
Increased amount of this neurotransmitter is perceived as pleasure, arousal, satisfaction, and also euphoria.
With time, you need to take larger and larger doses of the substance to achieve the same stimulating effect as before and to meet the constantly growing needs of the body, which leads to a strong addiction.
Role of dopamine as ketocholamine
Dopamine is not only a neurotransmitter in the central nervous system, it is also one of the three catecholamines, next to adrenaline and norepinephrine, synthesized by the coreadrenal glands.
It affects both the central and peripheral nervous system by acting on the dopamine D1 and D2 receptors as well as the alpha1 and beta1 adenergic receptors.
Dopamine synthesis in the adrenal glands
SCHEME Phenylalanine → Tyrosine → DOPA → Dopamine Dopamine is synthesized in the adrenal medulla from the amino acid tyrosine under the influence of two enzymes, tyrosine hydroxylase and dopa decarboxylase.
Animal protein, found in meat, fish and dairy products, is an excellent source of tyrosine.
Tyrosine is produced in a certain amount in the human body under the influence of biochemical changes of another amino acid, which is phenylalanine, but most of tyrosine comes from consumed food.
That is why it is so important to have a he althy, varied and balanced diet, rich in nutrients.
Dose-dependent dopamine effects
The healing effect of dopamine depends on the dose used. It is administered only intravenously after prior dilution in 5% glucose or saline solution.
- 0.5-2 µg / kg bw / min - the effect of the use of dopamine in small doses is the expansion of renal and visceral vessels in the human body. This causes an increase in blood flow through the kidneys, an increase in glomerular filtration and a greater amount of urine.
- 2-10 µg / kg bw / min - action through alpha 1 and beta 1 adrenergic receptors, which are located in the heart. The use of dopamine in such a dose results in an acceleration of heart rate, an increase in the strength of contraction of the heart muscle and an increase in cardiac output. As a consequence, it leads to an increase in systolic blood pressure and an improvement in the flow through the coronary vessels supplying the heart muscle with blood.
- >10 µg / kg bw / min - action through alpha 1 adrenergic receptors, which are located in the wall of blood vessels. The use of dopamine in such a dose causes constriction of the blood vessels. This leads to an increase in both systolic and diastolic blood pressure and a decrease in blood flow through the kidneys.
Indications for the use of dopamine
Dopamine is used in patients in shock, i.e. in a life-threatening condition, in which the demand of tissues for oxygen and nutrients is higher than their supply.
Incorrect, too late treatment may lead to multi-organ failure, and even the patient's death.
Hemodynamic disorders requiring the use of dopamine preparations occur, among others, in shockcardiogenic, post-traumatic and septic.
Patients who have undergone severe cardiac surgery and are in a state of decompensation of chronic congestive heart failure should also be monitored for circulatory disorders and possible dopamine treatment.
Worth knowingRole of dopamine in the endocrine system
Dopamine and prolactin
Prolactin is a hormone secreted by the pituitary gland. Physiologically, it is produced in small amounts during sleep, exercise, mental and physical stress, and sexual intercourse. The synthesis and secretion of prolactin increases significantly in pregnant and lactating women. Dopamine is a hormone produced by the hypothalamus that inhibits the release of prolactin.
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