Maternal hyperthyroidism in rats causes histomorphometric changes in the cranio-dental development of rat offspring at weaning

Abstract

IntroductionGestational hyperthyroidism is an important cause of bone modifications in offspring, resulting from changes in endochondral growth. However, its effect on the craniodental development in offspring is unknown. ObjectiveThe objective of this study was to demonstrate the effect of maternal hyperthyroidism on the craniodental development of offspring. MethodsFive pregnant Wistar rats with hyperthyroidism and five euthyroid rats were used in this study. At weaning, three pups per mother were selected from both groups. Blood was collected from the mothers on the day of birth of their offspring and from pups at weaning to measure plasma-free thyroxine levels. ResultsThe influence of maternal hormones on offspring was confirmed by thyroid histomorphometry. The size of the rostro-caudal and latero-lateral axes of the skull, frontal bone width, and the thicknesses of the sutures and the bones were measured. In the molar teeth, the thicknesses of the dentin, pre-dentin, and odontoblast layers, as well as the thickness of the periodontal ligament, were evaluated. The concentration of free T4 was higher in hyperthyroid rats. The height of the thyroid follicular epithelium was lower in offspring of hyperthyroid mothers. Additionally, these offsprings showed a reduction in the width of the frontal bones and an increase in suture thickness. The molars in the hyperthyroid mothers showed a reduction in the thickness of the odontoblast and pre-dentin layers and an increase in the thickness of the periodontal ligament. ConclusionWe conclude that maternal hyperthyroidism in rats causes significant changes in the cranialdental development of offspring.