Abstract
In this study, we continue our efforts toward the development of potent and highly selective histamine H(3) receptor agonists. We introduced various alkyl or aryl alkyl groups on the piperidine nitrogen of the known H(3)/H(4) agonist immepip and its analogues (1-3a). We observed that N-methyl-substituted immepip (methimepip) exhibits high affinity and agonist activity at the human histamine H(3) receptor (pK(i) = 9.0 and pEC(50) = 9.5) with a 2000-fold selectivity at the human H(3) receptor over the human H(4) receptor and more than a 10000-fold selectivity over the human histamine H(1) and H(2) receptors. Methimepip was also very effective as an H(3) receptor agonist at the guinea pig ileum (pD(2) = 8.26). Moreover, in vivo microdialysis (in rat brain) showed that methimepip reduces the basal level of brain histamine to about 25% after a 5 mg/kg intraperitoneal administration.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Binding, Competitive
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Cell Line
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Chlorocebus aethiops
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Cricetinae
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Cricetulus
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Electric Stimulation
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Guinea Pigs
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Histamine / metabolism
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Histamine Agonists / chemical synthesis*
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Histamine Agonists / chemistry
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Histamine Agonists / pharmacology
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Humans
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Hypothalamus / metabolism
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Ileum / drug effects
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Ileum / physiology
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Imidazoles / chemical synthesis*
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Imidazoles / chemistry
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Imidazoles / pharmacology
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In Vitro Techniques
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Male
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Microdialysis
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Muscle Contraction / drug effects
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Muscle, Smooth / drug effects
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Muscle, Smooth / physiology
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Piperidines / chemical synthesis*
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Piperidines / chemistry
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Piperidines / pharmacology
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Radioligand Assay
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Rats
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Rats, Wistar
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Receptors, Histamine H3 / drug effects*
Substances
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4-(imidazol-4-ylmethyl)-1-methylpiperidine
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Histamine Agonists
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Imidazoles
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Piperidines
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Receptors, Histamine H3
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4-(1H-imidazol-4-ylmethyl)piperidine
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Histamine