title: Chemical and ultrastructural identification of 5-hydroxytryptamine in an identified neuron.
abstract: The two largest cells in a typical ganglion of the leech (Hirudo medicinalis) nervous system are the colossal cells of Retzius. These cells show a positive chromaffin reaction, and it has been suggested that they contain 5-hydroxytryptamine (5-HT). In this study, the presence of 5-HT in the colossal cells was confirmed by microspectrofluorometry and by thin-layer chromatography and spectrofluorometry of extracts of individually dissected and pooled colossal cell bodies. A single colossal cell body was found to contain, on the average, 3.8 x 10(-10) g (6mM) 5-HT. Electron microscopy shows that the colossal cells are distinguished by the presence of 1000 A granules with irregular, electron-opaque cores. Since the granules are distributed in the same pattern as the 5-HT fluorescence, we have suggested that they contain 5-HT. Furthermore, a chromaffin reaction modified for the electron microscope provides evidence that 5-HT is present in the granule cores. These data can now serve as a basis for further studies on the metabolism, distribution, and function of 5-HT in these identified neurons.
mesh_terms: D000818:Animals; D002855:Chromatography, Thin Layer; D005724:Ganglia / Q000166:cytology; D006651:Histocytochemistry; D007865:Leeches; D008854:Microscopy, Electron; D009457:Neuroglia; D009474:Neurons / Q000032:analysis*; D012701:Serotonin / Q000032:analysis*; D013053:Spectrophotometry; D009435:Synaptic Transmission
chemical_list: D012701:Serotonin