Spinal cord serotonergic cells

The detection of serotonin in nervous and non-nervous tissue was aided by the development of the Falck-Hillarp histochemical technique, a method whereby freeze-dried sections of tissue, when exposed to formaldehyde vapour cause indoleamines to emit a yellow fluorescence. Dahlstrom and Fuxe used this technique to show that the highest concentration of serotonin in the brain is located in the raphe nuclei, projections from these cell bodies ascending to the forebrain via the medial forebrain bundle. Descending fibres were also shown to project to the dorsal and lateral horns and the intermediolateral column of the spinal cord. Detailed observation of the distribution of the serotonergic system in the brain became possible with... 

Serotonin (also known as 5-hydroxytryptamine) is released by cells originating in the midline of the pons and brainstem and is projected to many different areas, including the dorsal horns of the spinal cord and the hypothalamus. Serotonin is considered to be a strong inhibitor in most areas of the CNS and is believed to be important in mediating the inhibition of painful stimuli. It is also involved in controlling many aspects of mood and behavior, and problems with serotonergic activity have been implicated in several psychiatric disorders, including depression and anxiety.12,17 The roles of serotonin and the other monoamines in psychiatric disorders are discussed in Chapters 6-8. 

HT neurons originate in the raphe nudei in the midline region of the pons and upper brain stem. There are several serotonergic pathways in the CNS that innervate a variety of lower (e.g. medulla and spinal cord) and higher CNS centres such as cerebellum, thalamus, neocortex and the limbic system. Serotonergic nerve terminals are able to synthesise their own 5-HT from L-tryptophan, an ability they share with enterochromaffin cells. Neuronal reuptake and vesicular storage protects 5-HT from deamination by MAO. 

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