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False Neurotransmitter
A false neurotransmitter is a chemical compound which closely imitates the action of a neurotransmitter in the nervous system. Examples include 5-MeO-αMT (mimicking serotonin) and α-methyldopa. These chemicals can be accumulated by a neuron or secretory cell, are then packaged in secretory / synaptic vesicles, and then released with other neurotransmitters when an action potential provides the necessary stimulus for release. The concept of a false transmitter is credited to Irwin Kopin of the National Institute of Neurological Disorders and Stroke who determined that the drug tyramine increased blood pressure by being loaded and then released from secretory vesicles of the adrenal chromaffin cells. Tyramine can also be converted into octopamine by the dopamine-beta-hydroxylase (DBH) which itself acts as a false transmitter by displacing noradrenaline from its vesicle but not activating the postsynaptic alpha adrenoreceptor. There is growing evidence that a large number of well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different substance by a chemical reaction, which may involve interactions with other substances. In this process, bonds between atoms may be broken and/or new bonds formed. There are four major types of compounds, distinguished by how the constituent atoms are bonded together. Molecular compounds are held together by covalent bonds; ionic compounds are held together by ionic bonds; intermetallic compounds are held together by metallic bonds; coordination complexes are held together by coordinate covalent bonds. Non-stoichiometric compounds form a disputed marginal case. A chemical formula specifies the number of atoms of each element in a compound molecule, using ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |