A rodent model of schizophrenia derived from postmortem studies

Area of Science:

• Neuroscience
• Psychiatry
• Cellular Biology

Background:

• Postmortem studies suggest gamma-aminobutyric acid (GABA) cell dysfunction in schizophrenia pathophysiology.
• Abnormalities in the anterior cingulate cortex and hippocampus point to potential amygdala pathway involvement.
• Diminished GABAergic modulation is hypothesized to contribute to schizophrenia symptoms.

Purpose of the Study:

• To test the hypothesis that afferent fibers from the basolateral amygdala (BLA) influence GABAergic modulation in the hippocampus.
• To investigate the effects of pharmacologically increasing excitatory activity in the BLA on hippocampal GABAergic interneurons.
• To model functional changes in GABA cell subtypes relevant to schizophrenia.

Main Methods:

• Stereotactic infusion of picrotoxin (PICRO), a GABA-A receptor antagonist, into the BLA of rats.
• Assessment of GABAergic interneuron populations (parvalbumin, calbindin, calretinin) in hippocampal sectors CA3/2.
• Single-cell recordings in hippocampal slice preparations to measure synaptic potentials and neuronal firing rates.

Main Results:

• PICRO infusion selectively reduced specific GABAergic interneurons in hippocampal CA3/2.
• A decrease in evoked and spontaneous inhibitory postsynaptic potentials (sIPSCs) was observed in CA3/2 pyramidal neurons.
• Interneurons in the stratum oriens (SO) of CA2/3 exhibited altered membrane potential and increased firing rates, with elevated hyperpolarization-activated cationic currents (Ih).

Conclusions:

• Pharmacological activation of the BLA disrupts hippocampal GABAergic circuitry, mimicking observed postmortem abnormalities.
• These findings support the development of empirical models for schizophrenia research.
• The study provides a translational tool for investigating GABA cell subtypes and their regulatory mechanisms in schizophrenia.