A Selective Reduction in the Relative Density of Parvalbumin-immunoreactive Neurons in the Hippocampus in Schizophrenia Patients

Objectives: To determine the relative densities of the GABAergic subpopulation defined by calcium-binding proteins and to further study the importance of changes in GABAergic interneurons on neuropathology in the hippocampus in schizophrenia cases.

Methods: The relative densities and neuronal body size of cells immunoreactive for the calcium-binding proteins parvalbumin and calretinin as well as the area size of the hippocampal sub-fields were determined from the hippocampal tissue sections taken from schizophrenic patients and well-matched control subjects (15 per group).

Results: No significant difference in the density of calretinin-immunoreactive neurons and the neuronal body size of calretinin-positive neurons was found between subject groups. Relative to normal controls, schizophrenic patients showed a significant and profound deficit in the relative densities of parvalbumin-immunoreactive neurons in all hippocampal sub-fields. These reductions were more apparent in male schizophrenic patients and were unrelated to antipsychotic drug treatment, age or duration of illness.

Conclusion: The findings provide further evidence to support a profound and selective abnormality of a sub- population of GABAergic neurons in the hippocampus in schizophrenia cases, and are consistent with the etiological hypothesis of the neurodevelopment of schizophrenia.