Dietary zinc status reversibly alters both the feeding behaviors of the rats and gene expression patterns in diencephalon

Nutritional status influences feeding behaviors, food preferences and taste sensations. For example, zinc-deficient rats have been reported to show reduced and cyclic food intake patterns with increased preferences for NaCl. Although some impairments of the central nervous and endocrine systems have been speculated to be involved in these phenomena, the effects of short-term zinc deficiency on the brain have not been well examined to date. In this study, we performed a comprehensive analysis of the gene expression patterns in the rat diencephalon, which is a portion of the brain that includes the hypothalamus and thalamus, after short-term zinc deficiency and also during zinc recovery. The rats showed reduced and cyclic food intake patterns with increased salt preferences after a 10-day dietary zinc deficiency. A comparative analysis of their diencephalons using cDNA microarrays revealed that approximately 1% of the genes expressed in the diencephalons showed significantly altered expression levels. On the other hand, a 6-day zinc supplementation following the deprivation allowed for the recovery to initial food intake behaviors and salt preferences. The expression levels of most of the genes that had been altered by exposure to zinc deficient conditions were also recovered. These results show that feeding behaviors, taste preferences and gene expression patterns in the diencephalon respond quickly to changing zinc levels. This suggests that the gene expression changes observed in the diencephalon and the accompanying functional changes may be related to the development of deviations in feeding behaviors and increased preferences for NaCl in zinc-deficient rats.营养状态可对摄食行为、食物偏好及味觉感知产生调控作用。已有研究显示，锌缺乏（zinc deficiency）模型大鼠会表现出摄食量减少且呈周期性波动的进食模式，同时对氯化钠（NaCl）的偏好性显著增强。尽管有假说推测中枢神经系统与内分泌系统的功能损伤可能参与介导上述表型变化，但截至目前，短期锌缺乏对大脑的具体影响尚未得到充分探究。本研究针对短期锌缺乏状态及锌恢复阶段的大鼠间脑（diencephalon，即包含下丘脑（hypothalamus）与丘脑（thalamus）的脑区）的基因表达模式开展了全面分析。实验结果表明，经10天膳食锌缺乏干预的大鼠，确实呈现出摄食量减少且周期性波动的进食模式，同时对盐分的偏好性升高。通过cDNA微阵列（cDNA microarray）对大鼠间脑组织进行比较转录组分析后发现，间脑内表达的基因中约有1%的转录水平发生了显著改变。与之相对，在锌缺乏处理结束后进行6天的锌补充干预，可使大鼠的摄食行为与盐分偏好恢复至初始状态。多数因锌缺乏处理出现表达异常的基因，其转录水平也随之恢复至正常基线。上述研究结果证实，间脑内的摄食行为、味觉偏好以及基因表达谱均可对锌水平的动态变化做出快速响应。这提示，间脑内发生的基因表达改变及其伴随的功能变化，可能与锌缺乏大鼠出现的摄食行为异常以及对氯化钠偏好性升高的病理表型密切相关。