What are neurotransmitters? What neurotransmitters are associated with depression? Schizophrenia? Pain reduction? Parkinson's disease? Brain arousal? Muscle contractions?

Neurotransmitters are endogenous chemicals that are released by axon terminals of neurons into the synaptic junctions and act locally to control nerve cell functions.

•Imbalance of neurotransmitters such as serotonin, norepinephrine and dopamine have been linked with depression.

•Abnormal levels of neurotransmitter glutamate leads to changes in the level of Dopamine which can cause transition into psychosis. Dopamine has been implicated as possible cause of schizophrenia.

•Several transmitters are involved in analgesia system (pain suppression), especially involved are enkephalin and serotonin. When Serotonin are released and this causes local cord neurons ti secrete enkephalin, which is believed to cause both presynaptic and postsynaptic inhibition of pain fibres.

•Parkinson's disease also known as paralysis agitans results from widespread destruction of that portion of substantia nigra that sends dopamine-secreting nerve fibres to caudate nucleus and putamen this leads to decrease in dopamine.

•Acetylcholine is responsible brain arousal and muscle contraction.