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Synthesis of Serotonin in Traumatized Rat Brain
Author(s) -
Tsuiki K.,
Takada A.,
Nagahiro S.,
Grdiša M.,
Diksic M.,
Pappius H. M.
Publication year - 1995
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1995.64031319.x
Subject(s) - serotonin , dorsal raphe nucleus , serotonergic , neuroscience , raphe , raphe nuclei , lesion , cortex (anatomy) , medicine , neurotransmitter , endocrinology , biology , central nervous system , pathology , receptor
Previous studies have demonstrated that focal freezing lesions in rats cause a widespread decrease of cortical glucose use in the lesioned hemisphere and this was interpreted as a reflection of depression of cortical activity. The serotonergic neurotransmitter system was implicated in these alterations when it was shown that (1) cortical serotonin metabolism was increased widely in focally injured brain and (2) inhibition of serotonin synthesis prevented the development of cortical hypometabolism. In the present studies we applied an autoradiographic method that uses the accumulation of the 14 C‐labeled analogue of serotonin α‐methylserotonin to assess changes in the rate of serotonin synthesis in injured brain. The results confirmed that 3 days after the lesion was made, at the time of greatest depression of glucose use, serotonin synthesis was significantly increased in cortical areas throughout the injured hemisphere. The increase was also seen in the dorsal hippocampus and area CA3, as well as in the medial geniculate and dorsal raphe, but not in any other subcortical structures including median raphe. Present results suggest that the functional changes in the cortex of the lesioned hemisphere are associated with an increased rate of serotonin synthesis mediated by activation of the dorsal raphe. We also documented by α‐[ 14 C]aminoisobutyric acid autoradiography that there was increased permeability of the blood‐brain barrier, but this was restricted to the rim of the lesion.