Magnetic resonance imaging under isoflurane anesthesia alters cortical cyclooxygenase-2 expression and glial cell morphology during sepsis-associated neurological dysfunction in rats.

Background: Magnetic resonance imaging (MRI) of rodents combined with histology allows to determine what mechanisms underlie functional and structural brain changes during sepsis-associated encephalopathy. However, the effects of MRI performed in isoflurane-anesthetized rodents on modifications of the blood-brain barrier and the production of vasoactive prostaglandins and glia cells, which have been proposed to mediate sepsis-associated brain dysfunction, are unknown. Methods: This study addressed the effect of MRI under isoflurane anesthesia on blood-brain barrier integrity, cyclooxygenase-2 expression, and glial cell activation during cecal ligature and puncture-induced sepsis-associated brain dysfunction in rats. Results: Cecal ligature and puncture reduced food intake and the righting reflex. MRI under isoflurane anesthesia reduced blood-brain barrier breakdown, decreased circularity of white matter astrocytes, and increased neuronal cyclooxygenase-2 immunoreactivity in the cortex 24 hours after laparotomy. In addition, it annihilated cecal ligature and puncture-induced increased circularity of white matter microglia. MRI under isoflurane anesthesia, however, did not alter sepsis-associated perivascular cyclooxygenase-2 induction. Conclusion: These findings indicate that MRI under isoflurane anesthesia of rodents can modify neurovascular and glial responses and should, therefore, be interpreted with caution.