Physiological study on the role of zinc enzyme on the improvement of taste disorders

我们已经证实，在饲喂4天后，锌缺乏和低锌大鼠的NaCl偏好大于对照（锌充足和配对喂养）大鼠。此外，我们还报道了长期锌缺乏会降低鼓室索神经水平的味觉敏感性，并且锌缺乏导致的NaCl偏好变化发生在味觉敏感性下降之前。为了阐明锌缺乏和低锌大鼠在喂养早期对NaCl偏好增加的机制，我们研究了锌缺乏对血浆指数（矿物质浓度、pH值、红细胞压积）、血压、尿排泄、饮水量和选定激素的影响。4周龄雄性Sprague-Dawley大鼠分为缺锌组、低锌组和配对喂养组。在饲喂前期，缺锌大鼠血浆钠浓度无明显变化。我们还研究了锌缺乏对大鼠神经垂体激素的影响，因为大脑催产素系统通过影响钠的摄入和排泄来调节钠平衡。由此可见，饲喂缺锌日粮后4 d血浆催产素浓度下降。这些结果表明，锌缺乏的饮食信号可能反映了NaCl偏好，可能通过下丘脑-神经垂体系统。

We have confirmed that NaCl preference is greater in the zinc-deficient and low-zinc rats than in the control (zinc-sufficient and pair-fed) rats after 4 days' feeding. Furthermore, we have also reported that long-term zinc deficiency decreases taste sensitivity at the level of the chorda tympani nerve and that the change in NaCl preference due to zinc deficiency occurs before the decrease in taste sensitivity. In order to clarify the mechanism for the increased NaCl preference observed in zinc-deficient and low-zinc rats at an earlier stage of the feeding, we therefore investigated the effects of zinc deficiency on plasma index (mineral concentration, pH, hematocrit), blood pressure, urinary excretion, water intake and selected hormones. Male 4 week-old Sprague-Dawley rats were divided into three groups (zinc-deficient, low-zinc and pair-fed). At an earlier stage of the feeding period, there was no change of plasma sodium concentration in the zinc-deficient rats. We also investigated that the effects of zinc deficiency on neurohypophysial hormones in rats because brain oxytocin system is important for the regulation of sodium balance via effects on sodium intake and excretion. In consequence, the feeding of zinc-deficient diet causes the decrease of plasma oxytocin concentration even after 4 days' feeding. These results suggest that the dietary signal of zinc-deficiency may reflect NaCl preference, possibly through the hypothalamus-neurohypophysial system.