Parvalbumin neurons in the entorhinal cortex of subjects diagnosed with bipolar disorder or schizophrenia

Biol Psychiatry. 2007 Mar 1;61(5):640-52. doi: 10.1016/j.biopsych.2006.04.026. Epub 2006 Sep 1.


Background: Growing evidence indicates that the entorhinal cortex (ECx) might be affected in schizophrenia (SZ) and bipolar disorder (BD). To test whether distinct interneuronal subpopulations might be altered, numbers of parvalbumin-immunoreactive (PVB-IR) neurons were measured in the ECx of BD and SZ subjects. These neurons play a pivotal role within ECx intrinsic circuits.

Methods: Numbers, numerical density, and soma size of PVB-IR neurons were measured in the ECx of normal control (n = 16), BD (n = 10), and SZ (n = 10) subjects. The volume of the ECx was measured in Nissl-stained sections.

Results: In BD, decreases of total numbers (p = .02) and numerical densities (p = .01) of PVB-IR neurons were detected in the ECx. Within distinct subregions, reductions were detected in the superficial layers of the lateral (p = .02), intermediate (p = .04), and caudal (p = .01) ECx. In SZ, total numbers and numerical densities were not altered. A reduction of soma size was present in the intermediate ECx (p = .01). Volume was unaffected in either disorder.

Conclusions: In BD, a decrease of PVB-IR neurons may alter intrinsic inhibitory networks within the superficial layers of the ECx. The likely consequence is a disruption of integration and transfer of information from the cerebral cortex to the hippocampus.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Bipolar Disorder / pathology*
  • Cell Count
  • Entorhinal Cortex / pathology*
  • Female
  • Humans
  • Immunohistochemistry / methods
  • Male
  • Middle Aged
  • Neurons / metabolism*
  • Parvalbumins / metabolism*
  • Postmortem Changes
  • Schizophrenia / pathology*


  • Parvalbumins