Godino Andrea, De Luca Laurival Antonio, Antunes-Rodrigues José, Vivas Laura
Instituto de Investigación Médica Mercedes y Martín Ferreyra, Casilla de Correo 389, 5000-Córdoba, Argentina.
Am J Physiol Regul Integr Comp Physiol. 2007 Sep;293(3):R1027-36. doi: 10.1152/ajpregu.00078.2007. Epub 2007 Jun 13.
Previous studies demonstrated the inhibitory participation of serotonergic (5-HT) and oxytocinergic (OT) neurons on sodium appetite induced by peritoneal dialysis (PD) in rats. The activity of 5-HT neurons increases after PD-induced 2% NaCl intake and decreases after sodium depletion; however, the activity of the OT neurons appears only after PD-induced 2% NaCl intake. To discriminate whether the differential activations of the 5-HT and OT neurons in this model are a consequence of the sodium satiation process or are the result of stimulation caused by the entry to the body of a hypertonic sodium solution during sodium access, we analyzed the number of Fos-5-HT- and Fos-OT-immunoreactive neurons in the dorsal raphe nucleus and the paraventricular nucleus of the hypothalamus-supraoptic nucleus, respectively, after isotonic vs. hypertonic NaCl intake induced by PD. We also studied the OT plasma levels after PD-induced isotonic or hypertonic NaCl intake. Sodium intake induced by PD significantly increased the number of Fos-5-HT cells, independently of the concentration of NaCl consumed. In contrast, the number of Fos-OT neurons increased after hypertonic NaCl intake, in both depleted and non-depleted animals. The OT plasma levels significantly increased only in the PD-induced 2% NaCl intake group in relation to others, showing a synergic effect of both factors. In summary, 5-HT neurons were activated after body sodium status was reestablished, suggesting that this system is activated under conditions of satiety. In terms of the OT system, both OT neural activity and OT plasma levels were increased by the entry of hypertonic NaCl solution during sodium consumption, suggesting that this system is involved in the processing of hyperosmotic signals.
先前的研究表明，血清素能（5-羟色胺，5-HT）和催产素能（OT）神经元对大鼠腹膜透析（PD）诱导的钠食欲具有抑制作用。PD诱导2%氯化钠摄入后，5-HT神经元的活性增加，而钠缺乏后则降低；然而，OT神经元的活性仅在PD诱导2%氯化钠摄入后出现。为了区分该模型中5-HT和OT神经元的不同激活是钠饱足过程的结果，还是在钠摄入期间高渗钠溶液进入体内所引起的刺激的结果，我们分别分析了PD诱导的等渗与高渗氯化钠摄入后，下丘脑视上核背侧中缝核和室旁核中Fos-5-HT和Fos-OT免疫反应性神经元的数量。我们还研究了PD诱导的等渗或高渗氯化钠摄入后的OT血浆水平。PD诱导的钠摄入显著增加了Fos-5-HT细胞的数量，与所消耗的氯化钠浓度无关。相比之下，在高渗氯化钠摄入后，无论是钠缺乏还是非钠缺乏的动物，Fos-OT神经元的数量均增加。与其他组相比，仅在PD诱导2%氯化钠摄入组中OT血浆水平显著升高，显示出两种因素的协同作用。总之，在机体钠状态恢复后5-HT神经元被激活，表明该系统在饱足状态下被激活。就OT系统而言，在钠消耗期间高渗氯化钠溶液的进入增加了OT神经活性和OT血浆水平，表明该系统参与了高渗信号的处理。
