Changes of Monoamine Metabolites Measured by In Vivo Microdialysis in the Brainstem Following Experimental Subarachnoid Hemorrhage in Rats Katsutoshi Hirata 1 1Department of Neurosurgery, Nagasaki University, School of Medicine Keyword: subarachnoid hemorrhage , catecholaminergic neuron , nucleus tractus solitarius(NTS) , liquid chromatography , in vivo microdialysis pp.331-336
Published Date 1992/4/1
DOI https://doi.org/10.11477/mf.1406900320
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We investigated the function of monoaminergic neuron in the brainstem by measuring its metabolites using in vivo microdialysis following experimental subarachnoid hemorrhage in rats. Dialysis probe was implanted into the nucleus tractus solitarius (NTS) and continuous perfusion was then started. The perfusates were collected every 10-20 minutes and assayed by high-perfor-mance liquid chromatography (HPLC) with electro-chemical detection (ECD).

The main monoamine metabolites in extracel-lular space measured in NTS were 3 ,4-dihydroxy-phenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA). The extracellular content of DOPAC was abruptry increased after cisternal autologous blood (0.3m1) injection, reached a peak at 20-40 minutes, and then decreased over 120 minutes. The content of HVA and 5-HIAA changed as well as DOPAC. These results showed non-specific response for is-chemia of the brainstem, because the similar changes were seen after cisternal saline injection.

The disapperance rate of monoamine metabolites after pargyline administration (75 mg/kg, i. p.) at various time periods after cisternal blood injection was rapidest at 2 days after SAH and recovered gradually. In particular the decline curve of DOPAC consisted of two compartments and early compartment was disturved more severely than late compartment. These results indicate that the func-tional disturbance of nerve terminals is more severe than nerve cell body in adrenergic neurons.

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