Characterization of histamine H3 receptors in Alzheimer's Disease brain and amyloid over‐expressing TASTPM mice

Abstract

Background and purpose: Histamine H₃ receptor antagonists are currently being evaluated for their potential use in a number of central nervous system disorders including Alzheimer's Disease (AD). To date, little is known about the state of H₃ receptors in AD. Experimental approach: In the present study we used the radiolabelled H₃ receptor antagonist [³H]GSK189254 to investigate H₃ receptor binding in the amyloid over‐expressing double mutant APPswe × PSI.MI46V (TASTPM) transgenic mouse model of AD and in post‐mortem human AD brain samples. Key results: No significant differences in specific H₃ receptor binding were observed between wild type and TASTPM mice in the cortex, hippocampus or hypothalamus. Specific [³H]GSK189254 binding was detected in sections of human medial frontal cortex from AD brains of varying disease severity (Braak stages I–VI). With more quantitative analysis in a larger cohort, we observed that H₃ receptor densities were not significantly different between AD and age‐matched control brains in both frontal and temporal cortical regions. However, within the AD group, [³H]GSK189254 binding density in frontal cortex was higher in individuals with more severe dementia prior to death. Conclusions and implications: The maintenance of H₃ receptor integrity observed in the various stages of AD in this study is important, given the potential use of H₃ antagonists as a novel therapeutic approach for the symptomatic treatment of AD.