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    Home > Active Ingredient News > Study of Nervous System > "Dopamine" is a familiar and unfamiliar word, do you understand it?

    "Dopamine" is a familiar and unfamiliar word, do you understand it?

    • Last Update: 2021-04-24
    • Source: Internet
    • Author: User
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    *For medical professionals to read only for reference carbidopa, levodopa, piribedil sustained-release tablets, bromocriptine.
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    dopamine, do you often hear this term, this is not the one that makes people Happy, happy things? But why do we also use this drug when rescuing patients? So, "Carbidopa, Levodopa, Piribedil sustained-release tablets, Bromocriptine.
    .
    .
    " Are these words familiar? By the way, these are not drugs for treating Parkinson's.
    But it seems a bit unclear? What is the relationship between the commonly used antiemetics "metoclopramide and domperidone" and dopamine? Do you feel that your clear brain is starting to be confused again, then continue to look down, it will definitely make you suddenly enlightened! What exactly is dopamine? Do you often hear "Dopaminergic", which means "related to dopamine.
    "
    Dopamine (DA) is a catecholamine (including dopamine, epinephrine and norepinephrine) neurotransmitter synthesized in the brain or kidney, and it is found in plants and most animals.

    The chemical name is 4-(2-ethylamino)-1,2-benzenediol.

    For humans, dopamine is mainly synthesized in neuronal cells and adrenal medulla cells.

    Although dopamine is also found in many types of food, most of these dopamine cannot cross the blood-brain barrier.

    Therefore, it must be dopamine synthesized inside the brain to perform its activities related to neurons [1].

    What is the role of dopamine? (1) Dopamine works by binding to receptors ① Binding to dopamine receptors: it exists in the center and periphery.

    It has been found that DA receptors have 5 subtypes, D1, D2, D3, D4, and D5.
    D1-like receptors include D1 and D5, and D2-like receptors include D2, D3 and D4 receptors.
    D1-like receptor activation can be Arouse neuronal excitement, and D2-like receptor activation can inhibit the target neuron. ②Combined with human TAAR1 (trace amine related receptor 1): TAAR1 plays an important role in regulating the nerve conduction of dopamine and norepinephrine in the central nervous system.
    In addition, it can also affect the immune system and nervous immune system through different mechanisms.
    Features.

    ③Agitate the sympathetic nervous system: medium dose [2~10μg/(kg·min)] mainly excites β1 receptor agonism, positive muscle strength increases myocardial contractility and cardiac output; high dose dopamine [>10μg/ (kg·min)] It mainly activates alpha receptors, which strongly constricts the systemic circulation and visceral vascular bed, which increases systemic vascular resistance, increases systolic and diastolic blood pressure, and reduces renal vasoconstriction, renal blood flow and urine output.
    [2].

    (2) Acting through four pathways in the brain: control behavior (substantia nigra-striatal pathway): "substantia nigra" nerve nucleus, which exists in the midbrain → "substantia nigra-striatum pathway" → reaches up to the tail shape The core and putamen → determine whether our body movements can be coordinated and balanced (for example: Parkinson's disease).

    Reward system (pathway of the midbrain limbic system): the ventral tegmental area near the substantia nigra → the limbic lobe loop (amygdala, olfactory nodules, etc.
    ), which is closely related to behavioral motivation (for example: drug addiction, etc.
    ).

    Cognitive behavior (midbrain-cortex channel): the ventral tegmental area (VTA) near the substantia nigra → projects to the cortex such as the prefrontal lobe and cingulate gyrus to participate in the regulation of cognitive and thinking abilities, making behavior more rational.

    Endocrine regulation (nodular funnel channel): from arcuate nucleus, periventricular nucleus→projection to pituitary funnel nucleus→regulate the secretion of pituitary hormones (for example: prolactin, etc.
    ) [1].

    Dopamine-related drugs pseudo-dopamine drugs-levodopa, carbidopa, benserazide, methyldopa, dopasizide tablets, carbidopa-levodopa controlled-release tablets.

    Dopamine receptor agonists-ergotamines (bromocriptine, pergolide, aminoergoline, cabergoline, lisuride), non-ergots (pibedil, pramipexole, ropinirole, Rotigotine).

    Dopamine receptor antagonists-domperidone, metoclopramide, itopride.

    Dopamine-dopamine hydrochloride injection.

    Clinical application of dopamine drugs ①Dopamine-stimulates the sympathetic nervous system adrenal receptors (α, β receptors) and the effects of dopamine receptors located in the kidney, mesenteric, coronary and cerebral arteries, used to treat heart failure, shock and sepsis Disease and so on.

    But generally it has a dose-dependent effect: low dose [0.
    5~2μg/(kg·min)] excites dopamine receptors, dilates renal blood vessels, increases renal blood flow and glomerular filtration rate, and increases urine output; medium dose [2~ 10μg/(kg·min)] mainly excites β1 receptors, and positive inotropic action strengthens myocardial contractility and increases cardiac output; high-dose dopamine [>10μg/(kg·min)] uses activation of α receptors as Mainly, it will strongly contract the systemic circulation and visceral vascular bed, increase the systemic vascular resistance, increase the systolic and diastolic blood pressure, and reduce the renal vasoconstriction, renal blood flow and urine output.

    ② Dopamine receptor agonists-stimulating the effects of dopamine receptors, often used to treat Parkinson's disease, restless legs syndrome, prolactinoma, acromegaly [5], schizophrenia, male erectile dysfunction, etc.
    ③Dopamine drugs-exogenous dopamine cannot enter the brain through the blood-brain barrier (BBB), but its precursor levodopa can enter the brain through the BBB, and then be decarboxylated by dopa decarboxylase into dopamine, thereby Play a role in supplementing dopamine in the brain.

    As an alternative to dopamine, levodopa can enter the brain through the BBB.

    L-dopa decarboxylase is widely present in peripheral organs and blood vessel walls, so in the process of its absorption and transmission, most of it has been converted into dopamine, which can stimulate peripheral dopamine receptors and cause various peripheral side effects.

    Such as nausea, vomiting, anorexia and other gastrointestinal symptoms and lower blood pressure, arrhythmia and other cardiovascular symptoms.

    Extracerebral dopamine decarboxylase inhibitors, such as benserazide and methyldopahydrazine, cannot pass the BBB.
    When applied in small doses, they only inhibit the decarboxylation of levodopa outside the brain.

    Therefore, combined application with levodopa can prevent the formation of peripheral dopamine, thereby reducing the dosage of levodopa, enhancing its curative effect and reducing its peripheral side effects.

    ④ Dopamine receptor antagonists-antagonize dopamine receptors, have antiemetic and promote gastric emptying effects, and are often used to treat migraine, Parkinson's disease (such as levodopa, bromocriptine) and nausea and vomiting caused by radiotherapy Or gastrointestinal diseases such as functional dyspepsia, achalasia, gastritis, etc.

    Figure 1: Reference materials for clinical application of DA-related drugs: [1] Zhao Kejian, Editor-in-Chief.
    Handbook of Modern Pharmaceutical Terms.
    Beijing: China Medical Science and Technology Press.
    2004.
    Page 243.
    [2] Zhang Yuezhan.
    Research progress in clinical application of dopamine[J ].
    Journal of Intractable Diseases, 2013, 12(5): 401-403 [3] Zhao Jingping, Sun Mengxi, Zhao Jingping, Sun Mengxi, Dopamine and Mental Activity "Chinese Journal of Psychiatry" 2019, 52(4) 10.
    3760/cma.
    j .
    issn.
    1006-7884.
    2019.
    04.
    010 [4] Wang Xinde, Research progress in dopaminergic receptor agonist therapy "Chinese Journal of Geriatrics" 2004, 23 (07) [5] Chinese Medical Association Endocrinology Branch, Chinese Medical Association Neurosurgery Branch Chinese Medical Association Endocrinology Branch, Chinese Medical Association Neurosurgery Branch Acromegaly Diagnosis and Treatment Specification (Draft) "Chinese Journal of Neurosurgery" 2007, 23 (10)
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