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

我们已经报道了诱导干扰牙齿和牙源性肿瘤的NMU处理仓鼠的门牙，也证明了维生素A对肿瘤和干扰牙齿的影响。在本研究中，我们研究了天然和合成β-胡萝卜素对NMU处理的仓鼠的影响。在施用β-胡萝卜素后6小时，每周进行两次NMU治疗，持续三个月。NMU诱导的下颌切牙牙发育障碍的特点是发育不良的变化，从釉质发育不良到釉质丢失和不规则的发育不良的牙本质形成。在NMU处理的仓鼠，过量的β-胡萝卜素轻微抑制紊乱的牙发生，非典型增生的牙源性上皮，上皮成分的角化。在NMU抑制成釉细胞分化的情况下，成牙本质细胞的分化以及成釉细胞与成牙本质细胞之间的细胞间接触并没有受到阻止。β-胡萝卜素不能阻止NMU诱导的成釉细胞分化抑制，但能抑制NMU诱导的牙源性上皮角化。β-胡萝卜素对牙源性肿瘤的发生有一定的抑制作用。合成β-胡萝卜素似乎比天然β-胡萝卜素对牙齿发育中的NMU诱导的干扰稍微更有效。β-胡萝卜素可能在牙源性上皮组织的正常分化中发挥生物学功能和维生素原A功能。这项研究可能表明β-胡萝卜素对牙源性肿瘤发展的抑制作用是一种生物学功能，而不是维生素原A的功能。

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.