McCaughey S A, Giza B K, Scott T R
Department of Psychology, University of Delaware, Newark 19716, USA.
Physiol Behav. 1996 Aug;60(2):501-6. doi: 10.1016/s0031-9384(96)80025-4.
Sodium depletion has powerful effects on ingestive behavior. Depleted rats consume NaCl avidly at first, but decrease their intake to normal levels as they restore their sodium balance. However, vestiges of the depletion experience are expressed as a more rapidly induced and robust sodium consumption when the rat is challenged with a second depletion. Thus, the salience of sodium to the rat is modified in a lasting manner by severe deprivation. Sodium depletion also causes changes in the responses of taste cells in the nucleus tractus solitarius (NTS). In the present study, we examined whether gustatory-evoked responses in rat NTS continue to reflect the condition induced by sodium deprivation after sodium balance is restored. Single-unit recordings were made in response to 13 taste stimuli in two groups of rats: an experimental group that underwent 10-16 days of sodium deprivation followed by a 2-week recovery period, and a control group that never experienced deprivation. Experimental animals were tested for daily intake of 0.5 M NaCl before and after deprivation; they demonstrated a clear salt appetite only on the first day of the recovery period. Electrophysiological recordings revealed no significant differences between the two groups in response to any single stimulus. Neurons from each group of rats were categorized into three subtypes: sugar-sensitive, salt-sensitive, and nonsugar cells. A comparison of responses in these three subtypes offered no significant differences across groups. Thus, as rats restore depleted sodium levels following deprivation, the responsiveness of cells in the NTS also returns to a predeprivation state.
钠缺乏对摄食行为有强大影响。缺钠的大鼠起初会大量摄取氯化钠，但随着它们恢复钠平衡，摄入量会降至正常水平。然而，当大鼠再次面临缺钠挑战时，缺钠经历的痕迹表现为更快诱导且更强烈的钠摄取。因此，严重缺钠会以一种持久的方式改变钠对大鼠的显著性。钠缺乏还会导致孤束核（NTS）中味觉细胞反应的变化。在本研究中，我们研究了在钠平衡恢复后，大鼠NTS中味觉诱发反应是否继续反映钠缺乏所诱导的状态。对两组大鼠的13种味觉刺激进行单单位记录：一组实验组经历10 - 16天的钠缺乏，随后有2周的恢复期；另一组对照组从未经历过缺钠。在缺钠前后对实验动物进行0.5 M氯化钠的每日摄入量测试；它们仅在恢复期的第一天表现出明显的盐食欲。电生理记录显示，两组对任何单一刺激的反应均无显著差异。每组大鼠的神经元分为三种亚型：糖敏感型、盐敏感型和非糖细胞型。对这三种亚型反应的比较在两组之间未发现显著差异。因此，随着大鼠在缺钠后恢复耗尽的钠水平，NTS中细胞的反应性也恢复到缺钠前的状态。
