Association between maternal periapical lesions and brain inflammation in rat pups

The objective of this study was to determine whether the presence of maternal tooth periapical lesions was associated with foetal brain inflammation in a pregnant rat model.

Sprague-Dawley rats were divided into two groups: pregnant rats with induced periapical abscesses (E, n=8) and sham-operated control pregnant rats (S, n=8). The pulps of the first and second maxillary right molars had been exposed and the tooth left open to the oral environment for two weeks prior to initiation of the pregnancy. Following delivery of the pups (E, n=99; S, n=101), each pup was decapitated and the brain was removed and immediately frozen in liquid nitrogen. The tissues were solubilized in PBS containing a protease inhibitor, and norepinephrine (NE), IL-6, IL-1-β, TNF-α, and myelin basic protein (MBP) were determined by ELISA. Group means were compared by factorial analysis of variance, a post hoc Tukey test, and Pearson's correlation test. p<0.05 was used to reject the null hypothesis.

E pups were significantly heavier than S pups. Brain tissue concentrations of IL-6, IL-1-β, and TNF-α were significantly higher and MBP and norepinephrine concentrations significantly lower in E pups than S pups. Concentrations of IL-6, TNF-α and IL-1-β were significantly correlated between E serum, pup birthweight, and E pup brain tissue. MBP, NE and IL-6 were significantly correlated within the brain tissues of E pups.

The data suggest that brain inflammation may be associated with maternal periapical inflammation. This association identifies a modifiable risk factor for adverse pregnancy outcomes.