In vivo SPECT imaging of 5-HT(1A) receptors with [123I]p-MPPI in nonhuman primates Academic Article Article uri icon


MeSH Major

  • Fluorodeoxyglucose F18
  • Ovarian Neoplasms
  • Positron-Emission Tomography
  • Tomography, X-Ray Computed


  • The in vivo imaging of a novel iodinated phenylpiperazine derivative for 5-HT1A receptors, [123I]p-MPPI (4-(2'-methoxy-)phenyl-1-[2'-(n-2"-pyridinyl)-p-iodobenzamido-] ethyl-piperazine), using single photon emission computed tomography (SPECT), was evaluated in nonhuman primates. After an i.v. injection, [123I]p-MPPI penetrated the blood-brain barrier quickly and localized in brain regions where 5-HT1A receptor density is high (hippocampus, frontal cortex, cingulate gyrus, entorhinal cortex). Maximum ratio of hippocampus to cerebellum was 3 to 1 at 50 min postinjection. The specific binding of the radioligand in the hippocampal region, an area rich in 5-HT1A receptor density, was blocked by a chasing dose of (+/-) 8-OH-DPAT (2 mg/kg, i.v.) or non-radioactive p-MPPI (1 mg/kg, i.v.), whereas the regional distribution of [123I]p-MPPI was unaffected by treatment with non 5-HT1A agents, such as ketanserin. Ex vivo and in vitro autoradiographic studies using monkey brain further confirmed that the specific binding of [123I]p-MPPI is associated with 5-HT1A receptor sites. However, the initial attempt at [123I]p-MPPI human imaging studies did not display specific localization of 5-HT1A receptors. This discrepancy observed for [123I]p-MPPI may be due to a dramatic difference in metabolic pathways between humans and monkeys.

publication date

  • November 1996



  • Academic Article


Digital Object Identifier (DOI)

  • 10.1002/(SICI)1098-2396(199611)24:3<273::AID-SYN10>3.0.CO;2-Y

PubMed ID

  • 8923668

Additional Document Info

start page

  • 273

end page

  • 81


  • 24


  • 3