The benzodiazepine antagonist CGS 8216 prevents hyperammonemia-induced somatostatin receptor reduction in the brain

Previous results from our group showed that hyperammonemia decreases the number of somatostatin (SS) receptors and that benzodiazepine receptors might regulate the number of SS receptors in rat brain. These findings together with the supersensitivity of benzodiazepine receptors in the hyperammonemic...

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Bibliographic Details
Published in:Brain research 1995-08, Vol.688 (1), p.1-7
Main Authors: Boyano-Adánez, María del Carmen, Bodega, Guillermo, Martín-Espinosa, Ángela, Arilla, Eduardo
Format: Article
Language:English
Subjects:
Ammonia - blood
Ammonium acetate
Animals
Biological and medical sciences
Brain - drug effects
Brain - metabolism
CGS 8216
Frontoparietal cortex
GABA Antagonists - pharmacology
Hippocampus
Medical sciences
Metabolic diseases
Miscellaneous
Other metabolic disorders
Peptides - metabolism
Pyrazoles - pharmacology
Rat
Rats
Rats, Wistar
Receptors, Somatostatin - drug effects
Receptors, Somatostatin - metabolism
Somatostatin - metabolism
Somatostatin receptor
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Summary:Previous results from our group showed that hyperammonemia decreases the number of somatostatin (SS) receptors and that benzodiazepine receptors might regulate the number of SS receptors in rat brain. These findings together with the supersensitivity of benzodiazepine receptors in the hyperammonemic rat brain suggest that benzodiazepine receptors might mediate the effect of hyperammonemia on SS receptors. To assess this hypothesis we tested whether 2-phenylpyrazolo[3,4-c]-quinolin-3(5H)-one (CGS 8216), a benzodiazepine antagonist, prevented the effect of ammonium acetate on rat brain SS receptors. Administration of ammonium acetate (5 mmol/kg, i.p.) for 7 days did not affect the levels of somatostatin-like immunoreactivity but decreased the number of SS receptors in synaptosomes from the frontoparietal cortex and hippocampus without affecting their apparent affinity. This decrease could be blocked by the concomitant administration of CGS 8216 (10 mg/kg, i.p.). The benzodiazepine antagonist alone had no observable effect on the somatostatinergic system. These results suggested that the effect of hyperammonemia on SS receptors could be mediated, at least in part, through the benzodiazepine receptors.
ISSN:0006-8993
1872-6240
DOI:10.1016/0006-8993(95)00377-3