A Rodent Model of Anxiety: The Effect of Perinatal Immune Challenges on Gastrointestinal Inflammation and Integrity.

Objectives: Gastrointestinal (GI) inflammation and GI integrity deficits are common comorbidities of neuropsychiatric disorders. Ongoing research suggests that these aberrations may be contributing to heightened immune signals that have the potential to disrupt neuronal homeostasis and exacerbate behavioural deficits. The current study aimed to determine whether the well-characterized animal model of neuropsychopathology, the maternal immune activation (MIA) model, produced GI inflammation and integrity disruptions in association with anxiety-like behaviour.

Methods: Pregnant Wistar rats were exposed to the viral mimetic polyriboinosinic:polyribocytidilic acid (polyI:C) on gestational days (GD) 10 and 19. Evidence of ANS activation, GI inflammation, and GI barrier integrity was assessed in both neonatal (postnatal day, P7) and adult (P84) offspring. Anxiety-like behaviour was assessed at P100.

Results: Neonatal MIA offspring exhibited an altered intestinal inflammatory profile and evidence of an increase in lymphoid aggregates. MIA neonates also displayed disruptions to GI barrier tight junction protein mRNA. In addition, adult MIA offspring exhibited an increase in anxiety-like behaviours.

Conclusion: These results indicate that the MIA rat model, which is well documented to produce behavioural, neurochemical, and neuroanatomical abnormalities, also produces GI inflammation and integrity disruptions. We suggest that this model may be a useful tool to elucidate biological pathways associated with neuropsychiatric disorders.