It is found in enterochromaffin cells, platelets and in the brain. In the brain it is found mainly in the hypothalamus but there are special serotoninergic neurons which are neurotransmitter agents which extend from the raphe nuclei of the brain stem to the hypothalamus, limbic system, the neocrotex and the cerebellum. Disruption, of the synthesis, storage and release of serotonin causes some behavioral problems as the following will prove:

  • Lysergic acid diethylamide (LSD) which is a serotonin antagonist causes psycheielic phenomena.

  • Other tryptamine derived substances have psychotomimetic actions e.g. psilocybin.

  • Reserpine causes depletion of serotonin in the brain. It acts as a tranquillizer and also causes depression.

  • Monoamien oxidase inhibitors which are naturally supposed to break down excess monoamine cause accumulation of serotonin when used in treatment of depressive psychoses and therefore elevates mood.

  • Serotonin plays important role in regulation of some APUD hormone secretion e.g. adreno-hypophyssseal hormones.

  • Serotonin inhbits autonomic impulses in the intermedio-lateral column of the spinal cord.

  • Considerable amount of serotonin in the hypothalamus (which may be considered the leader of the diffuse neuroendocrine system) suggests a possible modulation of activity of the hypothalamus.















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