Endocrine Abstracts

The environment has become increasingly contaminated by various pollutants including endocrine disrupting chemicals (EDCs). This has led to an increase in the incidence and gravity of known pathologies and the emergence of new ones, including dental pathologies as the Molar Incisor Hypomineralization (MIH). Among the thousands of EDCs, bisphenol A (BPA) and phthalates (DEHP) are widely used by the plastic industry and responsible to frequent contaminations. We previously showed a link between experimental exposures to low-dose BPA and enamel defects similar to MIH (1). The characterization of enamel defects may be helpful to propose them as early markers of exposure to EDCs thanks to enamel unique properties.

The aims of the present work are 1) to compare mouse enamel defects resulting from exposure to low-dose BPA and/or DEHP and, 2) to approach the mechanism, of action of both EDCs during amelogenesis.

The study was carried out on mice exposed to 5 and 50 mg/kg per day DEHP with or without 5 μg/kg per day BPA. Exposed animals present enamel defects on their incisors with similar characteristics than those of MIH affected teeth. In addition, 11% of DEHP mice presented enamel breakdown suggesting a weak enamel structure. As both EDCs act through steroid receptors, their presence and expression levels were investigated in ameloblasts by immunofluorescent assays and RT-qPCR respectively. We found that dental epithelium express a specific combinatory of steroid receptors (AR, ERs, ERRs, RARα/RXRα, VDR, GR, MR and PGR) depending on their stage of differentiation. These data suggest that depending on their nature and the time of exposure, phthalates and BPA could affect enamel quality (through AR) and/or quantity (through ERRγ and ERα). Studies are currently driven to decipher the functional role of AR in the mechanism of action of both EDCs in ameloblasts.

References

(1) Jedeon et al., Am J Pathol, 2013, 183(1):108–18.