Effects of histamine H3-receptor ligands on brain monoamine oxidase in various mammalian species.
Brain Res
; 906(1-2): 180-3, 2001 Jul 06.
Article
em En
| MEDLINE
| ID: mdl-11430877
ABSTRACT
The effects of an H3 agonist, R-alpha-methylhistamine (alpha-MeHA), and an H3 antagonist, thioperamide, on monoamine oxidase (MAO) activity in the hypothalamus of rat, monkey and human brains were compared in vitro. The histamine H(3)-receptor ligands competitively inhibited MAO-B, but noncompetitively inhibited MAO-A in all three mammalian species. However, alpha-MeHA inhibited MAO-A more potently than MAO-B at high concentrations in all three species. The K(i) values for MAO-A of alpha-MeHA in hypothalamic homogenates of rat, monkey and human brains were estimated to be 1.1, 1.2 and 1.9 mM, respectively, suggesting that alpha-MeHA cannot behave as a substrate for the MAO inhibitor. In contrast, rat, monkey and human brain MAO-B activities were inhibited by thioperamide, with respective K(i) values of 174.6, 8.2 and 10.8 microM, more potently than MAO-A activity. These results indicate that thioperamide, which elicits a strong activation of histamine release and turnover to N-tele-methylhistamine from histamine, competitively inhibits the conversion of N-tele-methylhistamine to N-tele-methylimidazoleacetic acid in human and monkey brains where MAO-B predominates.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Frações Subcelulares
/
Agonistas dos Receptores Histamínicos
/
Receptores Histamínicos H3
/
Antagonistas dos Receptores Histamínicos
/
Hipotálamo
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Monoaminoxidase
/
Neurônios
Limite:
Aged
/
Animals
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Humans
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Middle aged
Idioma:
En
Revista:
Brain Res
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Japão