Maternal Rat Periapical Abscesses and Proinflammatory Cytokines in Pup Brains

Objective: The objective of this study was to determine if IL-1 beta was present within the brains of pups born to female rats with periapical abscesses.

Methods: Sprague–Dawley rats were divided into two groups: pregnant rats with induced periapical abscesses (n=16) and sham-operated controls (n=16). To induce periapical abscesses, the pulps of the first and second maxillary right molars of the experimental group were exposed using a ¼ round bur in a high-speed handpiece and 0.5µl of sterile bacterial lipopolysaccharide was placed into each pulp chamber. Two weeks later, both groups were bred. Following birth, the pups were weighed, measured, and the brains were removed. The left half of each cerebrum was homogenized in phosphate buffered saline containing a protease inhibitor (10 mg tissue/ml PBS solution). The right half was fixed and embedded in paraffin for immunohistochemistry. The tissue protein content was determined using a bicinchoinic acid protein assay. The concentration of IL-1 beta was determined by ELISA. The data was expressed as pg IL-1 beta/mg protein. The outcome variables were compared by factorial analysis of variance, post-hoc Tukey test, and Pearson's correlation test.

Results: The mothers with periapical abscesses had pups that were significantly heavier as compared to the control pups (p< 0.001). The mothers with abscesses had significantly higher serum concentrations of TNF-alpha, IL-6, and IL-1 beta compared to controls (p<0.001). Pup birth weight and brain IL-1 beta concentrations were significantly correlated with the presence of maternal serum IL-1 beta (p<0.001).

Conclusion: Periapical abscesses in pregnant rats may result in brain inflammation in their offspring. Brain inflammation in a developing animal is known to adversely affect brain myelinization. There could be an association between this type of abscess and neurological development.

Study supported by UMC-SOD Intramural Grant.