Agonists and antagonists

Any substance that binds to the receptor known as ligands: By preventing the action of an agonist called agonists and antagonists, without activating them, their ligands that activate receptors, receptor I occupy the body. Under normal circumstances, i.e., a ligand that acts on receptors We are substances generated in the body itself which are “endogenous”. However, by binding to specific receptors, particularly drugs, many produce action treatment of those organisms. Typically, these drugs are not the same as the endogenous ligand, but it is synthetic or animal-derived materials and different plants acts as a ligand “external” These. There are two reasons for not using the endogenous substances, such as such therapeutic agents. First, in order to activate the receptor by endogenous ligands that occur naturally, many drugs, is efficient agonist much actually. Then, in the case of drugs that act to prevent over-body systems, the action of endogenous ligands blocks are needed, an antagonist that binds to the receptor.


If there Reinventions all internal chemistry of our own, in the words of other drugs – if there is endogenous ligand equivalent, all drugs that work by stimulating receptors might wonder. Consider the morphine analgesic, it is of plant origin, has an expression something different in the body. I say working in Aberdeen in 1970, Hans Costa Ritz, the endogenous ligand associated actually for non-endogenous agonist of all of them. He continued to John Hughes of his colleagues in order to find a natural painkiller is the endogenous ligand enkephalin, morphine acts of opium receptor. Currently, the same argument seems to be true of cannabinoid seen (such as barium for example) thebenzodiazepines relieve anxiety and marijuana. It is known as receptor “orphan” receptors of these: that many drugs that are thought to function in the event the receptor and so there is no endogenous ligand known of course is left.



Receptor antagonist responds when it itself is bound to the receptor biological, but it is a type of drug, and receptor ligands that do not delay the agonist-mediated response induce or block. Rather than affinity pharmacological antagonist, has the efficiency related these receptors, prevents binding interactions, and inhibit the function of a receptor agonist or inverse agonist. Antagonists, usually, or they mediate their effects by binding (or ortho exact site =) active allosteric site on (= site) receptor sites involved in the regulation of the biological activity of the receptor it is possible to interact with specific binding sites not. In turn, depends on the nature of the binding of the receptor antagonist, antagonist activity, antagonist – may be reversible or irreversible depending on the length of the receptor complex. Most of the narcotic antagonists, to achieve the effect by competing with the substrate or endogenous ligand in the binding site structurally different receptor.

The partial agonist, is identified as being of a particular receptor, may function of the amplitude response is different that they create the maximum capacity after the receiving. Agonists, they are partial agonists, but, compared to that observed completely so that it conflicts with the full agonist occupancy of the receptor, produced a net decrease of activation of the receptor by it, the full agonist agonist alone can act as a competitive antagonist in the presence of. Clinically, their usefulness is derived from the ability while blocking excessive activity and to improve the system of the defect. Exposing the receptor to a high level of partial agonist ensures that certain activities, at low level, an agonist of the normal whether present at a level higher or lower. In addition, to prevent the adaptive control mechanism to develop after repeated exposure to the antagonist or full agonist powerful often is assumed to agonism partial. Partial agonist buprenorphine, the μ-opioid receptor is associated with low morphine-like activity, as analgesics, or be used as an alternative to methadone for the treatment of opioid addiction in the treatment of clinical pain.

Inverse agonist has the same effect as an antagonist, it can cause a separate set of biological events downstream. The receptor activity, for example, not only block the action of an agonist as an antagonist of binding classic, not only inhibit the basal activity of the receptor is an inverse agonist constitutively showing the basal activity or endogenous get. Currently, many drugs that are classified as antagonists previously has been reclassified as inverse agonists receptor since a constitutively active. Classification antihistamines, have been reclassified as inverse agonists as antagonists of H1 histamine receptors initially.

This is due to antagonist and exogenous agonists endogenous (such as medicine) (for example, such as hormones and neurotransmitters) or that the receptor is inactivated or activated, or can be, by inhibition or stimulation of biological response some. Physiological agonists are substances that create the effect the same body, but does not bind to the same receptor. Endogenous agonist for a particular receptor is a compound that forms in the body to naturally activated by binding with the receptor. For example, the endogenous agonist at serotonin receptors endogenous agonist of dopamine and serotonin receptors, some dopamine.

The super-agonist is a compound which can generate a greater than the maximum response of the endogenous agonist for the target receptor, and thus efficiency is 100% or more. Necessarily, this is stronger than the endogenous agonist is it, but it does not mean that the maximum possible response that can be produced in a cell receptor binding after, is much more than. To be (has an affinity) to indicate the full efficacy at that receptor full agonist binds to receptor activation. Examples of agents that act as a full agonist isoproterenol, that mimic the action of adrenaline tail adrenergic receptors. In another example, in the central nervous system – is a mimic the action of morphine endorphins opioid receptors.

Bound (eg, norclozapine buspirone, aripiprazole, or buprenorphine) the even partial agonist, activating the receptor, compared with a full agonist, it is effective only partially to the receptor. Partial agonist studies of benzodiazepine sedative hypnotic aggressive that you have the power of less than half of full agonists. Partial agonist reduces the severity of withdrawal syndrome with and dependence Abecarnil as indicates a lower rate. Is a drug that binds to the receptor binding site the same as the agonist of the receptor, inverse agonists, and draw a constitutive activity of the receptor. Inverse agonists, exert opposite the pharmacological effects of the receptor.

(- “To fight for the prize” antagonist s “opponent, rival, enemy, rival,” from anti-agonizesthai “opposite” from Greece) antagonist It is a sign of the organization represents the opposition to the main character should be maintained or group, of character. In other words, the antagonist, is a person or group of people who oppose the main character (s). In the classic style of the story, which consists in the hero and fighting villain / enemy, respectively, can be regarded as antagonist and protagonist They action. Without her instructions or him intentionally, antagonist can be an obstacle or threat to the hero of the existence necessarily. In the film, in the example of theater, Sauron, and Romeo and the main antagonist of the main fighting ring, and kill Tibaruto, the Merkutsio, resulted in the death of exiled hero of the game, the Romeo after the heroes of the series always I include the antagonist of Juliet. Treaty of antagonism is that moral choices that their is a spicy than the hero in the story. This is often used by the author to create a collision in the story. However, this is just a convention, reversal of this can be found in the character of Macbeth McDermott staff morally right in his desire to fight the tyrant Macbeth probably.