Serotonin 1A receptors in the living brain of Alzheimer's disease patients

Vladimir Kepe, Jorge R. Barrio, Sung Cheng Huang, Linda Ercoli, Prabha Siddarth, Kooresh Shoghi-Jadid, Gregory M. Cole, Nagichettiar Satyamurthy, Jeffrey L. Cummings, Gary W. Small, Michael E. Phelps

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184 Scopus citations


4-[F-18]fluoro-N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl} -N-(2-pyridinyl)benzamide, a selective serotonin 1A (5-HT1A) molecular imaging probe, was used in conjunction with positron emission tomography (PET) for quantification of 5-HT1A receptor densities in the living brains of Alzheimer's disease patients (ADs) (n = 8), subjects with mild cognitive impairment (n = 6), and controls (n = 5). ADs had receptor densities significantly decreased in both hippocampi (binding potential: controls 1.62 ± 0.07; ADs 1.18 ± 0.26) and also in raphe nuclei (controls 0.63 ± 0.09; ADs 0.37 ± 0.20). When volume losses are included, 5-HT1A losses are even more severe (i.e., average mean decreases of 24% in mild cognitive impairment patients and 49% in ADs). A strong correlation of 5-HT1A receptor decreases in hippocampus with worsening of clinical symptoms (Mini Mental State Exam scores) was also found. Moreover, these decreases in 5-HT1A receptor measures correlate with decreased glucose utilization as measured with 2-deoxy-2-[F-18]fluoro-D-glucose PET in the brains of ADs (standardized uptake values; globally: controls 0.89 ± 0.04, ADs 0.72 ± 0.04; posterior cingulate gyrus: controls 1.05 ± 0.09, ADs 0.79 ± 0.11). They also inversely correlate with increased neuropathological loads measured with 2-(1-{6-[(2-[F-18]fluoroethyl) (methyl)amino]-2-naphthyl}ethylidene)malononitrile PET in several neocortical regions in the same subjects. The in vivo observations were confirmed independently by in vitro digital autoradiography with 4-[F-18]fluoro-N-{2-[4- (2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridinyl)benzamide and 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}-ethylidene) malononitrile on brain tissue specimens from two ADs and three nondemented subjects.

Original languageEnglish
Pages (from-to)702-707
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number3
StatePublished - Jan 17 2006


  • Brain 5-HT receptors
  • Neuronal loss
  • Positron emission tomography
  • [F-18]MPPF


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