Taste and Cyclophosphamide in Mice

描述(申请人提供)：被广泛用于治疗癌症的环磷酰胺(CYP)将作为研究新问题的典型药物，如化疗药物如何破坏味觉，味蕾中的细胞群体如何更新，以及我们如何保护这些细胞免受化疗药物的影响。化疗引起的味觉丧失往往会减少食物的摄入量，导致营养不良，生活质量下降，康复较差， 并增加了死亡率。之前的研究主要集中在这些药物的恶心和其他副作用如何形成减少食物消耗的条件性食物厌恶，或者这些药物如何扰乱唾液功能。然而，还没有人问过这些药物对味觉上皮有何影响。CYP在有丝分裂过程中破坏DNA，从而针对参与高有丝分裂的细胞，如癌症或具有高自我更新率的组织的成体祖细胞。被CYP攻击的非癌症细胞在其细胞周期中被阻止，直到其DNA修复或细胞死亡。在行为学研究中，一次剂量的CYP破坏了小鼠在注射后5天内辨别两种相似味道的能力，并在注射后8-12天再次中断。味觉细胞的寿命为8-12天。当它们死亡时，它们被来自味蕾底部周围的祖细胞的细胞所取代。我们的初步发现表明，CYP会杀死或破坏味觉上皮中的祖细胞，当幸存的味觉细胞在8-12天后死亡时，没有足够的替代细胞来维持正常的味觉功能，直到细胞更新周期重新开始。这项拟议的研究有三个具体目的来验证我们的假设，即CYP诱导味蕾中的细胞死亡，并阻止通常取代味觉细胞的前体细胞的有丝分裂活动。这两种作用都会扰乱味觉功能，但在药物治疗后的不同时间。目的1将通过测试小鼠对甜、酸、苦和盐的敏感度和味觉敏锐度来评估CYP改变小鼠味觉功能的程度。目标2将确定f CYP通过杀死味觉细胞和停止味觉细胞替换周期来破坏味觉。其他单元格 标记物将用于确定祖细胞何时重新启动其细胞周期以产生替代味觉细胞，以及特定味觉细胞类型何时开始发挥功能。目的3将测试氨磷汀是否可以防止味觉丧失，并探索它如何防止CYP诱导的味觉细胞死亡。虽然这项研究的重点是化疗药物和味觉，但它使用了一种新的行为和细胞分析相结合的方法，利用味觉细胞的短暂寿命来研究味蕾在正常和受伤后重新繁殖。这项研究将为未来更密切地研究化疗药物的作用机制、味觉细胞更新的过程以及保护味觉细胞免受癌症治疗的有害影响的可能机制奠定基础。癌症治疗是与癌症治疗相关的一个重大健康问题。更广泛地说，该模型可用于研究其他形式的损伤，如辐射，并适用于研究其他组织的快速细胞更替。

DESCRIPTION (provided by applicant): Cyclophosphamide (CYP), widely used to treat cancer, will serve as a prototypical agent to study novel questions about how chemotherapy drugs disrupt taste, how cell populations within taste buds are renewed, and how we might protect these cells from the effects of chemotherapy drugs. Taste loss caused by chemotherapy frequently reduces food intake and results in malnutrition, lower quality of life, poorer recovery, and increased mortality. Prior research has focused mostly on how nausea and other side effects of these drugs form conditioned food aversions that reduce food consumption, or how these drugs disrupt salivary function. However, no one has asked how these drugs affect taste epithilium. CYP damages DNA during mitosis and thus targets cells engaged in high rates of mitosis such as cancer or adult progenitor cells of tissues with high rates of self-renewal. A noncancerous cell attacked by CYP is arrested in its cell cycle until its DNA is repaired, or the cell dies. In behavioral studies, one dose of CYP disrupted the ability of mice to discriminate between two similar tastes for up to 5 days post injection and again at 8-12 days post injection. Taste sensory cells have life spans of 8-12 days. When they die, they are replaced by cells derived from progenitor cells around the base of taste buds. Our initial findings suggest CYP kills or damages progenitor cells in taste epithelium and when surviving taste cells die 8-12 days later, there are insufficient replacement cells to maintain normal taste functions until the cell-renewal cycle is restarted. The proposed research has 3 Specific Aims to test our hypothesis that CYP induces cell death in taste buds and arrests mitotic activity of progenitor cells that normally replace taste sensory cells. Both effects disrupt taste functions but at different times after drug treatment. Aim 1 will assess the extent to which CYP alters taste functions of mice by testing their sensitivity and taste acuity for sweet, sour, bitter, and salt. Aim 2 will determine f CYP disrupts taste by killing taste cells and stopping the taste cell replacement cycle. Other cell markers will be used to determine when progenitor cells restart their cell cycles to generate replacement taste cells, and when specific taste cell types become functional. Aim 3 will test if amifostine can prevent taste loss and explore how it prevents taste cell death induced by CYP. Although this research is focused on chemotherapy drugs and taste, it uses a novel combination of behavioral and cellular assays that capitalize on the short life span of taste cells to study ho taste buds are repopulated, normally and after injury. This research will lay the foundation for future studies that more closely examine mechanisms underlying the effects of chemotherapy drugs, the processes underlying taste cell renewal, and possible mechanisms that can protect taste cells from the deleterious effects of cancer treatments, a significant health issue associated with the treatment of cancer. More broadly, this model can be used to study other forms of injury such as irradiation and is applicable for studying other tissues with rapid cell turnover.