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Sympatholytic
A sympatholytic (or sympathoplegic) drug is a medication that opposes the downstream effects of postganglionic nerve firing in effector organs innervated by the sympathetic nervous system (SNS). They are indicated for various functions; for example, they may be used as antihypertensives. They are also used to treat anxiety, such as generalized anxiety disorder, panic disorder and PTSD. In some cases, such as with Guanfacine, they have also shown to be beneficial in the treatment of ADHD. Mechanisms of action Antiadrenergic agents inhibit the signals of epinephrine and norepinephrine. They are primarily postsynaptic adrenergic receptor antagonists (alpha and beta adrenergic receptor antagonists, or "blockers"), inhibiting the downstream cellular signaling pathways of adrenergic receptors. However, there are exceptions: clonidine is an adrenergic agonist at the α2 receptor; since this receptor is located presynaptically, agonism at this receptor inhibits the presynaptic r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norepinephrine
Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', "near", and ''ren'', "kidney") is more commonly used in the United Kingdom, whereas "norepinephrine" (from Ancient Greek ἐπῐ́ (''epí''), "upon", and νεφρός (''nephrós''), "kidney") is usually preferred in the United States. "Norepinephrine" is also the international nonproprietary name given to the drug. Regardless of which name is used for the substance itself, parts of the body that produce or are affected by it are referred to as noradrenergic. The general function of norepinephrine is to mobilize the brain and body for action. Norepinephrine release is lowest during sleep, rises during wakefulness, and reaches much higher levels during situations of stress or danger, in the so-called fight-or-flight response. In th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prazosin
Prazosin is an α1 blocker medication primarily used to treat high blood pressure, symptoms of an enlarged prostate, and nightmares related to post-traumatic stress disorder (PTSD). It is a less preferred treatment of high blood pressure. Other uses may include heart failure and Raynaud syndrome. It is taken by mouth. Common side effects include dizziness, sleepiness, nausea, and heart palpitations. Serious side effects may include low blood pressure with standing and depression. Prazosin is a non-selective inverse agonist of the α1-adrenergic receptors. It works to decrease blood pressure by dilating blood vessels and helps with an enlarged prostate by relaxing the outflow of the bladder. How it works in PTSD is not entirely clear. Prazosin was patented in 1965 and came into medical use in 1974. It is available as a generic medication. In 2020, it was the 190th most commonly prescribed medication in the United States, with more than 2million prescriptions. Medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clonidine
Clonidine, sold under the brand name Catapres among others, is an α2-adrenergic agonist medication used to treat high blood pressure, ADHD, drug withdrawal ( alcohol, opioids, or nicotine), menopausal flushing, diarrhea, spasticity, and certain pain conditions. It is used by mouth, by injection, or as a skin patch. Onset of action is typically within an hour with the effects on blood pressure lasting for up to eight hours. Common side effect include dry mouth, dizziness, headaches, hypotension, and sleepiness. Severe side effects may include hallucinations, heart arrhythmias, and confusion. If rapidly stopped, withdrawal effects may occur. Use during pregnancy or breastfeeding is not recommended. Clonidine lowers blood pressure by stimulating α2 receptors in the brain, which results in relaxation of many arteries. Clonidine was patented in 1961 and came into medical use in 1966. It is available as a generic medication. In 2020, it was the 75th most commonly pres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postganglionic
In the autonomic nervous system, fibers from the ganglion to the effector organ are called postganglionic fibers. Neurotransmitters The neurotransmitters of postganglionic fibers differ: * In the parasympathetic division, neurons are ''cholinergic''. That is to say acetylcholine is the primary neurotransmitter responsible for the communication between neurons on the parasympathetic pathway. * In the sympathetic division, neurons are mostly ''adrenergic'' (that is, epinephrine and norepinephrine function as the primary neurotransmitters). Notable exceptions to this rule include the sympathetic innervation of sweat glands and arrectores pilorum muscles where the neurotransmitter at both pre and post ganglionic synapses is acetylcholine. Another notable structure is the medulla of the adrenal gland, where chromaffin cells function as modified post-ganglionic nerves. Instead of releasing epinephrine and norepinephrine into a synaptic cleft, these cells of the adrenal medulla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synaptic Vesicle
In a neuron, synaptic vesicles (or neurotransmitter vesicles) store various neurotransmitters that are released at the synapse. The release is regulated by a voltage-dependent calcium channel. Vesicles are essential for propagating nerve impulses between neurons and are constantly recreated by the cell. The area in the axon that holds groups of vesicles is an axon terminal or "terminal bouton". Up to 130 vesicles can be released per bouton over a ten-minute period of stimulation at 0.2 Hz. In the visual cortex of the human brain, synaptic vesicles have an average diameter of 39.5 nanometers (nm) with a standard deviation of 5.1 nm. Structure Synaptic vesicles are relatively simple because only a limited number of proteins fit into a sphere of 40 nm diameter. Purified vesicles have a protein:phospholipid ratio of 1:3 with a lipid composition of 40% phosphatidylcholine, 32% phosphatidylethanolamine, 12% phosphatidylserine, 5% phosphatidylinositol, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imidazoline Receptor
Imidazoline receptors are the primary receptors on which clonidine and other imidazolines act. There are three main classes of imidazoline receptor: I1 is involved in inhibition of the sympathetic nervous system to lower blood pressure, I2 has as yet uncertain functions but is implicated in several psychiatric conditions, and I3 regulates insulin secretion. Classes As of 2017, there are three known subtypes of imidazoline receptors: I1, I2, and I3. I1 receptor The I1 receptor appears to be a G protein-coupled receptor that is localized on the plasma membrane. It may be coupled to PLA2 signalling and thus prostaglandin synthesis. In addition, activation inhibits the sodium-hydrogen antiporter and enzymes of catecholamine synthesis are induced, suggesting that the I1 receptor may belong to the neurocytokine receptor family, since its signaling pathways are similar to those of interleukins. It is found in the neurons of the reticular formation, the dorsomedial medulla oblongata, ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rilmenidine
Rilmenidine is a prescription medication for the treatment of hypertension. It is marketed under the brand names Albarel, Hyperium, Iterium and Tenaxum. Form and composition Each tablet contains 1.544 mg rilmenidine dihydrogen phosphate, an amount equivalent to 1 mg of rilmenidine base. Mode of action Rilmenidine, an oxazoline compound with antihypertensive properties, acts on both medullary and peripheral vasomotor structures. Rilmenidine shows greater selectivity for imidazoline receptors than for cerebral alpha2-adrenergic receptors, distinguishing it from reference alpha2-agonists. Indications Hypertension. Contraindications Severe depression, severe kidney failure ( creatinine clearance <15 ml/min), as a precaution in the absence of currently available studies. Warning Therapy should never be interrupted suddenly; the dosage should be reduced gradually.Precautions * As with all antihypertensive agents, regular medi ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACE Inhibitor
Angiotensin-converting-enzyme inhibitors (ACE inhibitors) are a class of medication used primarily for the treatment of high blood pressure and heart failure. They work by causing relaxation of blood vessels as well as a decrease in blood volume, which leads to lower blood pressure and decreased oxygen demand from the heart. ACE inhibitors inhibit the activity of angiotensin-converting enzyme, an important component of the renin–angiotensin system which converts angiotensin I to angiotensin II, and hydrolyses bradykinin. Therefore, ACE inhibitors decrease the formation of angiotensin II, a vasoconstrictor, and increase the level of bradykinin, a peptide vasodilator. This combination is synergistic in lowering blood pressure. As a result of inhibiting the ACE enzyme in the bradykinin system, the ACE inhibitor drugs allow for increased levels of bradykinin which would normally be degraded. Bradykinin produces prostaglandin. This mechanism can explain the two most common si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rescinnamine
Rescinnamine, known by the brand names moderil, cinnasil, and anaprel, is an angiotensin-converting enzyme inhibitor used as an antihypertensive drug. It is a vinca alkaloid obtained from ''Rauvolfia serpentina'' and other species of ''Rauvolfia ''Rauvolfia'' (sometimes spelled ''Rauwolfia'') is a genus of evergreen trees and shrubs, commonly known as devil peppers, in the family Apocynaceae. The genus is named to honor Leonhard Rauwolf. The genus can mainly be found in tropical regi ...''. References Indoloquinolizines Tryptamine alkaloids Isoquinoline alkaloids ACE inhibitors Antihypertensive agents Alkaloids found in Rauvolfia Pyrogallol ethers Cinnamate esters Indole ethers at the benzene ring {{Antihypertensive-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha-1 Blocker
Alpha-1 blockers (also called alpha-adrenergic blocking agents or alpha-1 antagonists) constitute a variety of drugs that block the effect of catecholamines on alpha-1-adrenergic receptors. They are mainly used to treat benign prostatic hyperplasia (BPH), hypertension and post-traumatic stress disorder. Alpha-1 adrenergic receptors are present in vascular smooth muscle, the central nervous system, and other tissues. When alpha blockers bind to these receptors in vascular smooth muscle, they cause vasodilation. Over the last 40 years, a variety of drugs have been developed from non-selective alpha-1 antagonists to selective alpha-1 antagonists and alpha-1 inverse agonists. The first drug that was used was a non-selective alpha blocker, named phenoxybenzamine and was used to treat BPH. Currently, several relatively selective alpha-1 antagonists are available. As of 2018, prazosin is the only alpha-1 blocker known to act as an inverse agonist at all alpha-1 adrenergic recept ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
6-hydroxydopamine
Oxidopamine, also known as 6-hydroxydopamine (6-OHDA) or 2,4,5-trihydroxyphenethylamine, is a neurotoxic synthetic organic compound used by researchers to selectively destroy dopaminergic and noradrenergic neurons in the brain. The main use for oxidopamine in scientific research is to induce Parkinsonism in laboratory animals by lesioning the dopaminergic neurons of the substantia nigra pars compacta, in order to develop and test new medicines and treatments for Parkinson's disease. History The neurontoxin oxidopamine has first been described in 1959. Years later, in 1968 the first model exploiting oxidopamine neurotoxicity was developed by Ungerstedt, obtaining an animal model of akineasia with a very high mortality rate. Ever since, oxidopamine has become an abundantly used neurotoxin for making animal models with Parkinson’s disease. Usage The toxin oxidopamine, an antagonist of the neurotransmitter dopamine, and is commonly used for making experimental animal models ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanethidine
Guanethidine is an antihypertensive drug that reduces the release of catecholamines, such as norepinephrine. Guanethidine is transported across the sympathetic nerve membrane by the same mechanism that transports norepinephrine itself (NET, uptake 1), and uptake is essential for the drug's action. Once guanethidine has entered the nerve, it is concentrated in transmitter vesicles, where it replaces norepinephrine. It may also inhibit the release of granules by decreasing norepinephrine. Medical uses Guanethidine was once a mainstay for hypertension resistant to other agents, and was often used safely during pregnancy, but it is no longer used in the US due to lack of availability. It is still licensed in some countries, e.g., UK, for the rapid control of blood pressure in a hypertensive emergency. Intravenous nerve block ( Bier block) using guanethidine has been used to treat chronic pain caused by complex regional pain syndrome. Side effects Side effects include postural and ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
