Influence on Indian hedgehog-parathyroid hormone-like related protein pathway induced by altered masticatory loading in the condylar cartilage of growing rabbits

To determine the influence of altered masticatory loading on Indian hedgehog (Ihh)-parathyroid hormone-like related protein (PThrP) pathway in the condylar cartilage of growing rabbits. A total of 48 10-day-old rabbits were randomly divided into two groups and fed different kinds of food, such as solid diet and soft diet. The animals were sacrificed after 2, 4, 6, and 8 weeks. Difference of Ihh and PThrP expression levels induced by altered masticatory loading was tested by hematoxylin-eosin (HE), immunohistochemistry, Western blot, and real-time polymerase chain reaction (PCR). The thickness of condylar cartilage and expression levels of Ihh and PThrP proteins and mRNA of the solid diet groups exceeded those of the soft diet groups. The decreasing tendencies of the expression levels of Ihh and PThrP proteins and mRNA were observed at 2, 4, 6, 8 weeks. Low masticatory loading may delay or inhibit the development of condylar cartilage and its growing factors Ihh and PThrP. Therefore, masticatory loading plays