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Characterization of Extracellular Histamine in the Striatum and Bed Nucleus of the Stria Terminalis of the Rat: An In Vivo Microdialysis Study
Author(s) -
Cumming P.,
Damsma G.,
Fibiger H. C.,
Vincent S. R.
Publication year - 1991
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 - 10.1111/j.1471-4159.1991.tb02083.x
Subject(s) - microdialysis , histamine , extracellular , stria terminalis , striatum , chemistry , medicine , endocrinology , in vivo , histamine h3 receptor , biology , dopamine , biochemistry , central nervous system , antagonist , receptor , microbiology and biotechnology
The intracerebral microdialysis technique, coupled with a sensitive radioenzymatic assay, was employed to study histamine release in the striatum and in the bed nucleus of the stria terminalis (BNST) in conscious, freely moving rats. In these brain regions, extracellular histamine concentrations decreased by 20% when calcium was omitted from the perfusion solution. Extracellular histamine was insensitive to the addition of tetrodotoxin to the perfusion medium. In striatum, extracellular histamine concentrations declined in an apparent biexponential manner after the administration of α‐fluoromethylhistidine, an inhibitor of histamine synthesis. The half‐lives for the disappearance of histamine were 32 min and 7.7 h, indicating the presence of at least two histamine pools. Histidine loading resulted in a nearly twofold increase in histamine outflow in striatum. In the BNST, yohimbine increased the extracellular histamine content by 50%, suggesting that histamine release is subject to α 2 ‐adrenergic regulation in vivo. The extent to which histamine detected in cerebral microdialysis samples is of neurogenic origin remains to be established.