Effect of beta-carotene on epithelio-mesenchymal interaction during ocbntogenesis and oncogenesis in NMU-treated hamster

Research Project

Project/Area Number	06671800
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Morphological basic dentistry
Research Institution	HOKKAIDO UNIVERSITY
Principal Investigator	KOHGO Takao Sch.of Dent., Hokkaido Univ., Asso.Prof., 歯学部, 助教授 (80001949)
Co-Investigator(Kenkyū-buntansha)	SHINDOH Masanobu Sch.of Dent., Hokkaido Univ., Asst., 歯学部, 助手 (20162802)
Project Period (FY)	1994 – 1995
Project Status	Completed (Fiscal Year 1995)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1994: ¥1,700,000 (Direct Cost: ¥1,700,000)
Keywords	Odontogenic tumor / beta-carotene / Disturbances in odontogenesis / Hamster / N-nitrosomethylurea / 上皮間葉相互作用 / 歯方形成異常 / N-nitrosomethylurea / 上皮-間葉相互作用
Research Abstract	We have reported the induction of disturbances in odontogenesis and odontogenic tumors in incisors of NMU-treated hamsters, and also demonstrated the effects of vitamin A on tumorigenesis and disturbances in odontogenesis. In the present study, we investigated the effect of natural and synthetic beta-carotene on NMU-treated hamsters. Six hours after administration of beta-carotenes, NMU treatment was conducted twice a week for three months. The NMU-induced disturbances in the odontogenesis of mandibular incisors were characterized by hypoplastic changes ranging from enamel hypoplasia to loss of enamel and irregular hypoplastic dentin formation. In NMU-treated hamsters, excess administration of beta-carotene slightly repressed disturbances in odontogenesis, atypical proliferation of odontogenic epithelium, and keratinization of epithelial components. In NMU inhibited ameloblast differentiation, the differentiation on odontoblasts and cell to cell contact between preameloblasts and odontoblasts were not prevented. The beta-carotene did not prevent NMU-induced inhibition of ameloblast differentiation but inhibited NMU-induced keratinization of odontogenic epithelium. The beta-carotene had a moderate suppressive effect on the development of the odontogenic tumors. Synthetic beta-carotene seems to be slightly more effective on NMU-induced disturbances in odontogenesis than natural beta-carotene. The beta-carotene may play a role in the normal differentiation of odontogenic epithelial tissue as a biological function and as a provitamin A function. This study may suggest inhibitory effects of beta-carotene on odontogenic tumor development as a biological function rather than as a provitamin A function.