[3H]-Flunitrazepam-labeled Benzodiazepine Binding Sites in the Hippocampal Formation in Autism: A Multiple Concentration Autoradiographic Study

  • Jeffrey T. Guptill
  • Anne B. Booker
  • Terrell T. Gibbs
  • Thomas L. Kemper
  • Margaret L. Bauman
  • Gene J. BlattEmail author
Original Paper


Increasing evidence indicates that the GABAergic system in cerebellar and limbic structures is affected in autism. We extended our previous study that found reduced [3H]flunitrazepam-labeled benzodiazepine sites in the autistic hippocampus to determine whether this reduction was due to a decrease in binding site number (B max) or altered affinity (K d) to bind to the ligand. Quantitation of hippocampal lamina demonstrated a 20% reduction in B max indicating a trend toward a decreased number of benzodiazepine binding sites in the autistic group but normal K d values. A reduction in the number of hippocampal benzodiazepine binding sites suggests alterations in the modulation of GABAA receptors in the presence of GABA in the autistic brain, possibly resulting in altered inhibitory functioning of hippocampal circuitry.


Developmental disorder Autoradiography Hippocampus GABAergic receptors Hippocampal circuitry 



This research was supported by NIH NINDS NS38975-01A1 (Dr. Margaret L. Bauman, P.I.). Brain tissue was provided by the Harvard Brain Tissue Resource Center (HBTRC) (Francine Benes, M.D., Ph.D., Director) and from the Autism Tissue Program (ATP) (Jane Pickett, Ph.D., Director) via the University of Miami and the University of Maryland Brain Banks. The authors would like to thank Dr. Susan Blease and Claudia Fitzgerald for their help with tissue processing.


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Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  • Jeffrey T. Guptill
    • 1
  • Anne B. Booker
    • 1
  • Terrell T. Gibbs
    • 2
  • Thomas L. Kemper
    • 1
  • Margaret L. Bauman
    • 1
  • Gene J. Blatt
    • 1
    Email author
  1. 1.Department of Anatomy and NeurobiologyBoston University School of MedicineBostonUSA
  2. 2.Department of Pharmacology and TherapeuticsBoston University School of MedicineBostonUSA

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