Insulin-like Growth Factor Expression in Malnourished Rat Dental Pulp

This study evaluated the expression levels of IGF-I, insulin peptides, and their respective receptors, IGF-IR and IR, in the dental pulp of rats subjected to protein malnutrition. The nourished group (N) received a diet with 20% casein, while the malnourished group (M) received a diet with 5% casein. The renourished group (R) consisted of M group members maintained on the N group diet from the 22nd to the 60th day of life to evaluate the effects of renourishment. Dental pulps of the maxillary first molars were stained with hematoxylin and eosin, and picrosirius red, and were subjected to immunohistochemical tests. Malnutrition altered the odontoblastic layer and the collagen component of the dental pulp. IGF-I and IGF-IR expression levels were higher in the N group but there were no differences in the insulin expression levels between the groups. IR immunoexpression was higher in the N group compared with groups M and R. The results suggest that protein deprivation changed the constitution of the dental pulp and affected the factors that influence its development. The process of renutrition during puberty was not able to support the recovery of pulp morphology.