Auditory information processing in rat genotypes with different dopaminergic properties.

Area of Science:

• Neuroscience
• Psychiatry
• Genetics

Background:

• Auditory filtering disturbances, assessed via sensory gating and prepulse inhibition (PPI), are implicated in schizophrenia.
• Dopamine (DA) agonists can impair auditory evoked potential (AEP) gating and PPI in healthy subjects, suggesting a role for DA hyperactivity.
• Comparing rat genotypes with distinct DA systems offers a non-invasive method to study DA's role in AEP gating and PPI.

Purpose of the Study:

• To investigate whether PPI and AEP gating are disturbed in rats with heightened mesolimbic DA reactivity (APO-SUS, WAG/Rij) or nigrostriatal DA activity (APO-UNSUS, ACI).
• To determine if the balance between nigrostriatal and mesolimbic DA systems influences deficits in PPI and AEP gating.

Main Methods:

• Comparison of four rat genotypes (APO-SUS, APO-UNSUS, ACI, WAG/Rij) with varying DA balances in the AEP gating paradigm.
• PPI measurement in ACI and WAG/Rij rats, building on prior findings of diminished PPI in APO-SUS rats.

Main Results:

• WAG/Rij rats exhibited significantly reduced AEP gating of the vertex N50 compared to APO-SUS, APO-UNSUS, and ACI rats.
• No PPI deficits were observed in ACI or WAG/Rij rats, despite higher basal startle amplitude in ACI rats.

Conclusions:

• A PPI deficit is associated with high mesolimbic DA reactivity and low nigrostriatal DA activity.
• N50 gating deficits in WAG/Rij rats suggest that high nigrostriatal DA activity and high mesolimbic DA reactivity are necessary for this deficit.
• Auditory filtering processes (PPI and AEP gating) are differentially regulated by dopamine in the nigrostriatal and mesolimbic systems.