Neurotransmitters

From Drug Rehab Wiki

Neurotransmitters are chemicals that allow neurons to communicate with each other via movement across the synapse (gap between two neurons). Neurotransmitters are released from one neuron at the presynaptic nerve terminal and cross over the synapse to the next neuron’s receptor. The chemical will only bind to specific receptors that recognize it. The receptor is then activated by either depolarization, making it more likely that the neuron will fire, or hyperpolarization, making a firing much less likely.

To be considered a neurotransmitter, the chemical must be both made and found within the neuron. When a neuron is stimulated, it must release the chemical and, when it is released, the chemical must act on a post-synaptic receptor and produce a biological effect. After the chemical is released it must be deactivated, either through reuptake or by an enzyme designed to stop the chemical action. If the chemical acts on a post-synaptic membrane, it must have the same effect as when it is released by a neuron. Typical types of neurotransmitters include small molecule neurotransmitter substances (acetylcholine, serotonin, dopamine, histamine, norepinephrine, and epinephrine), amino acids (GABA, glutamate), neuroactive peptides (insulin, glucagon) and soluble gases like nitric oxide and carbon monoxide. A neurotransmitter can be neutralized by seeping out of the synaptic cleft before acting on a receptor; by deactivation, whereby a specific enzyme changes the structure of the chemical so that the receptor will no longer recognize it; by removal via glial cells; and by reuptake, the process by which the neurotransmitter is drawn back up into the neuron that released it. Norepinephrine, dopamine, and seratonin are all neutralized by reuptake.