Imaging histamine H1 receptors in the living human brain with carbon-11-pyrilamine

V. L. Villemagne, R. F. Dannals, P. M. Sanchez-Roa, H. T. Ravert, S. Vazquez, A. A. Wilson, T. K. Natarajan, D. F. Wong, K. Yanai, H. N. Wagner

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


The brain distribution and kinetics of the H1 receptor antagonist, carbon-11-pyrilamine (11C-pyrilamine) were examined in vivo in two baboons and one human by positron emission tomography. After i.v. administration of the tracer, brain activity peaked within 20 min after injection and subsequently decreased, reflecting reversible binding to the receptor. Pretreatment with 1 mg/kg diphenhydramine reduced the brain activity at 70 min by 33%, 29%, 26%, and 23% of the control values in frontal cortex, temporal cortex, hippocampus, and cerebellum, respectively. Coinjection of 1 and 5 mg/kg cold pyrilamine reduced the activity at 70 min by 40%, 36%, 34%, and 30% in frontal, temporal, hippocampus and cerebellum, respectively. The in vivo specific binding to the H1 receptors in different brain regions at 70 min after injection correlated with the in vitro H1 histamine receptors distribution in human brain tissue obtained at autopsy, with high values in the frontal and temporal cortex and low values in cerebellum and brain stem. In the healthy human volunteer study, the value of washout of radioactivity increased by about 50% after injection of 0.7 mg/kg diphenhydramine.

Original languageEnglish
Pages (from-to)308-311
Number of pages4
JournalJournal of Nuclear Medicine
Issue number2
StatePublished - 1991


Dive into the research topics of 'Imaging histamine H1 receptors in the living human brain with carbon-11-pyrilamine'. Together they form a unique fingerprint.

Cite this