The Effect on Notch Signaling Induced by Altered Mastication

Objectives: The aim of this study was to demonstrate the effect of altered mastication on Notch signaling, especially the gene and protein expression of Notch-1, Notch-3, Jagged-1 and Delta-like1 in growing rabbits’ condylar cartilage.
Methods:
Forty-eight ten-day old rabbits, which would not be weaned until the second week of the experience, were randomly divided into two groups: hard-diet group and soft-diet group (experimental and control groups). Then the animals in soft-diet groups were fed on a powdered diet, while the ones in hard-diet groups were fed on a solid diet from 2 to 8 weeks. The animals were sacrificed at 2, 4, 6 and 8-week time points. The condylar cartilage would be harvested, and the expression of Jagged-1 protein and gene expressions of Notch-1, Notch-3, Jagged-1 and Delta-like 1 would be tested by western blot and real-time PCR respectively.
Results:
The expression tendency of four genes was similar: 1) expressions in hard-diet groups were higher than the ones in soft-diet groups. 2) the quantities reached the top at 4-week time points, then decreasing. Notch-3 and Delta-like1 showed greatly significant difference at 4-week time point. And the significant difference involved Jagged-1 was identified at 4- and 6-week time points. However, there was no significant difference about Notch-1. Also, the quantities of Notch-1, Notch-3, Jagged-1 and Delta-like1 were getting closer no matter in soft-diet group or the hard-diet group. The similar expression tendence had been noticed in Jagged-1. And it expressed more in hard-diet groups. There were significant differences at 2-, 4- and 6- time points.
Conclusions:
The altered mastication in growing rabbits, induced by low mechanical loading, changed the expression of the Notch-1, Notch-3, Jagged-1 and Delta-like 1, revealing that the mastication has influenced on the regulation of Notch signaling, along with the development of condylar cartilage.