Mahía Javier, Bernal Antonio, Puerto Amadeo
Department of Psychobiology, University of Granada, Granada, Spain,
Acta Neurobiol Exp (Wars). 2013;73(3):326-37. doi: 10.55782/ane-2013-1940.
Lesions in the hypothalamic median eminence (ME) induce polydipsia and polyuria in male rats. A first experiment was designed to examine the effect of salt consumption (standard 0.25 percent Na+ vs. low-salt 0.04 percent Na+ diet) on the fluid-electrolytic balance (plasma sodium, urinary sodium excretion, urine osmolality) and water intake of ME polydipsic animals. In the first 6 h post-surgery, the natriuretic response was higher in ME-lesioned animals than in control groups. At 24 h post-surgery, however, less sodium was excreted by ME rats fed with a standard salt diet (ME/SS), despite showing no decrease in salt intake, and they evidenced an increase in plasma sodium concentration and water intake. Urine osmolality was significantly higher in control animals than in either ME-lesioned group. In experiment 2, hypertonic NaCl administration (2 ml/2M) increased the polydipsic behavior of ME-lesioned but not control rats (day 2). Animals deprived of food/salt showed a significant reduction (on day 2) in the initial (day 1) polydipsia, which increased on day 3 when the animals had access to a standard-salt diet. These results suggest that the reduced natriuretic response and the consequent sodium retention observed in ME animals may exacerbate the hydromineral imbalance of this polydipsic syndrome.
下丘脑正中隆起（ME）的损伤会诱发雄性大鼠出现烦渴和多尿症状。首个实验旨在研究盐摄入量（标准的0.25% Na⁺ 饮食与低盐的0.04% Na⁺ 饮食）对ME烦渴动物的液体 - 电解质平衡（血浆钠、尿钠排泄、尿渗透压）及水摄入量的影响。在手术后的最初6小时内，ME损伤动物的利钠反应高于对照组。然而，在手术后24小时，尽管喂食标准盐饮食的ME大鼠（ME/SS）盐摄入量未减少，但它们排出的钠却更少，且血浆钠浓度和水摄入量增加。对照组动物的尿渗透压显著高于任一ME损伤组。在实验2中，注射高渗氯化钠（2 ml/2M）增加了ME损伤大鼠而非对照大鼠的烦渴行为（第2天）。禁食/禁盐的动物（第2天）初始（第1天）的烦渴症状显著减轻，而在第3天动物能够获取标准盐饮食时，烦渴症状又有所加重。这些结果表明，在ME动物中观察到的利钠反应降低及随之而来的钠潴留可能会加剧这种烦渴综合征的水盐失衡。
