Differential growth of craniofacial and tibial bones to sympathetic hyperactivity-related hypertension in rats

Publication date: Available online 3 January 2019

Source: Archives of Oral Biology

Author(s): Yuta Uchikawa, Jun Hosomichi, Jun-ichi Suzuki, Hiroyuki Yamaguchi, Yuji Ishida, Kasumi Hatano, Risa Usumi-Fujita, Yasuhiro Shimizu, Sawa Kaneko, Shunsuke Uesugi, Takashi Ono

Abstract

Objective

To evaluate the effect of sympathetic nervous system hyperactivity on craniofacial skeletal growth in growing spontaneously hypertensive rats (SHRs).

Design

Craniofacial skeletal growth was compared between male SHR and Wistar―Kyoto rats (WKR) using linear measurements on lateral and transverse cephalometric radiographs at the age of 12 weeks. Tibia length was measured as an index of whole body growth. Body weight　and blood pressure were measured from 3 to 12 weeks of age. Bone microstructure in the mandibular condyle and tibia between the two groups was compared at the age of 12 weeks using microcomputed tomography.

Results

The SHRs had a significantly lower body weight than WKRs from 7 weeks of age, and tibial length was significantly smaller in the SHRs than in the WKR at 12 weeks of age. In all SHRs, blood pressure was significantly higher than in WKRs from 3 to 12 weeks of age. Cephalometric analyses revealed decreased measurements of the neurocranium, viscerocranium, and mandible in SHRs, and mandibular growth was most negatively affected in this group. Lastly, in SHRs, microcomputed tomography analyses revealed decreased bone mineral density and bone volume/tissue volume in the mandibular condyle but not in the tibia.

Conclusion

In growing SHRs, hypertension related to the hyperactivity of the sympathetic nervous system reduced craniofacial skeletal growth more than the growth of the tibia.

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