Neurotransmitter

Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a neuron and another cell. According to the dogma of the 1960's, a chemical can be classified as a neurotransmitter if it respects the following conditions:

Specific actions

While some neurotransmitters (glutamate, GABA, glycine) are used very generally throughout the central nervous system, others are only used in certain brain regions by particular classes of nerve cells. Serotonin is released specifically by cells in the brainstem, in an area called the raphe nuclei. Dopamine classically modulates two systems: the brain's reward mechanism, and movement control.

Related Topics:
Serotonin - Dopamine

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Neurotransmitters which have these types of specific actions are often targeted by drugs. Cocaine, for example, blocks the reuptake of dopamine, leaving these neurotransmitters in the synaptic gap longer. Prozac is a serotonin reuptake inhibitor, hence potentiating its effect. AMPT prevents the conversion of tyrosine to L-DOPA, the precursor to dopamine; reserpine prevents dopamine storage within vesicles; and deprenyl inhibits monoamine oxidase (MAO) B and thus increases dopamine levels.

Related Topics:
Cocaine - Dopamine - Synaptic gap - Prozac - AMPT - L-DOPA - Reserpine - Deprenyl - Monoamine oxidase

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Finally, some neurotransmitter/neuromodulators like zinc can not only modulate the sensitivity of a receptor to other neurotransmitters (allosteric modulation) but can even penetrate specific, gated channels in post synaptic neurons, thus entering the post synaptic cells. This "translocation" is another mechanism by which synaptic transmitters can affect postsynaptic cells.

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Diseases may affect specific neurotransmitter pathways. For example, Parkinson's disease is at least in part related to failure of dopaminergic cells in deep-brain nuclei, for example the substantia nigra. Treatments potentiating the effect of dopamine precursors have been proposed and effected, with moderate success.

Related Topics:
Parkinson's disease - Deep-brain nuclei

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