Decreased brain histamine-releasing factor protein in patients with Down syndrome and Alzheimer's disease.

Histamine-releasing factor (HRF) stimulates secretion of histamine that is widely distributed in brain and released as neurotransmitter. Several studies suggested that histaminergic deficits could contribute to the cognitive decline in Alzheimer's disease (AD). Based upon deranged histamine metabolism in brain of patients with AD and Down Syndrome (DS), we aimed to study HRF in brain of AD and DS. We used two-dimensional gel electrophoresis, matrix-assisted laser desorption ionization mass spectroscopy and specific software to quantify HRF. HRF was significantly reduced in temporal cortex, thalamus and caudate nucleus of DS and in temporal cortex of AD as compared to controls. This is the first report to show decreased HRF brain levels in DS and AD suggesting the explanation for the decreased cognitive function in neurodegenerative/dementing disorders.