Sodium intake by hyperosmotic rats treated with a GABAA receptor agonist into the lateral parabrachial nucleus
Sodium intake by hyperosmotic rats treated with a GABAA receptor agonist into the lateral parabrachial nucleus
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DOI：
10.1016/j.brainres.2007.11.004
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发表时间：
2008-01-23
期刊：
影响因子：
2.9
通讯作者：
Callera, Joao Carlos
中科院分区：
文献类型：
--
作者：
Kimura, Everton Heidi;Oliveira, Lisandra B.;Callera, Joao Carlos
臂旁外侧核(LPBN)的抑制机制和中枢GABA能机制参与水和盐摄取的调节。除了增加液体耗竭引起的钠摄入量外，在正常血压和正常水合状态下，通过激活GABA(A)受体进入下丘脑核内，还能诱导0.3M氯化钠的摄取。有人认为，渗透压信号激活的抑制机制被LPBN中GABAA受体的激活所阻断，从而增加了高渗盐的摄入量。因此，在本研究中，我们观察了下丘脑室旁核注射蝇草酚对高渗细胞脱水大鼠(灌胃2M氯化钠)水摄入量和0.3M氯化钠摄入量的影响。雄性Wistar大鼠双侧LPBN内植入不锈钢套管。在完全水化的大鼠中，双侧侧臂旁核注射蝇草酚(0.5nmol/0.2亩L)，可引起0.3M氯化钠(24.6+/-7.9vs溶剂：0.5+/-0.3ml/180min)和水(6.3+/-2.1vs溶剂：0.5+/-0.3ml/180min)的摄入。在2M氯化钠负荷(2ml)后1h，双侧LPBN内注射蝇草酚也可引起0.3M氯化钠摄入量(22.1+/-5.2vs.0.9+/-0.8ml/210min)和水摄入量(16.5+/-3.6mlvs.7.8+/-1.8ml/210min)。下丘脑核内注入GABA受体拮抗剂荷包牡丹碱(0.4nmol/0.2亩L)，可降低蝇草酚对0.3M氯化钠摄入量(7.1+/-2.1ml/210min)的影响。因此，激活LPBN中的GABAA受体可诱导高渗细胞脱水大鼠摄取0.3M的氯化钠，提示血浆肾素水平或渗透压不影响LPBN抑制机制阻断后的钠摄取。(C)2007 Elsevier B.V.保留所有权利。
Inhibitory mechanisms in the lateral parabrachial nucleus (LPBN) and central GABAergic mechanisms are involved in the regulation of water and NaCl intake. Besides increasing fluid depletion-induced sodium intake, the activation of GABA(A) receptors with muscimol into the LPBN also induces ingestion of 0.3 M NaCl in normonatremic, euhydrated rats. It has been suggested that inhibitory mechanisms activated by osmotic signals are blocked by GABAA receptor activation in the LPBN, thereby increasing hypertonic NaCl intake. Therefore, in the present study we investigated the effects of muscimol injected into the LPBN on water and 0.3 M NaCl intake in hyperosmotic cell-dehydrated rats (rats treated with an intragastric load of 2 M NaCl). Male Wistar rats with stainless steel cannulas implanted bilaterally into the LPBN were used. In euhydrated rats, muscimol (0.5 nmol/0.2 mu l), bilaterally injected into the LPBN, induced ingestion of 0.3 M NaCl (24.6 +/- 7.9 vs. vehicle: 0.5 +/- 0.3 ml/180 min) and water (6.3 +/- 2.1 vs. vehicle: 0.5 +/- 0.3 ml/180 min). One hour after intragastric 2 M NaCl load (2 ml), bilateral injections of muscimol into the LPBN also induced 0.3 M NaCl intake (22.1 +/- 5.2 vs. vehicle: 0.9 +/- 0.8 ml/210 min) and water intake (16.5 +/- 3.6 vs. vehicle: 7.8 +/- 1.8 ml/210 min). The GABAA antagonist bicuculline (0.4 nmol/0.2 mu l) into the LPBN reduced the effect of muscimol on 0.3 M NaCl intake (7.1 +/- 2.1 ml/210 min). Therefore, the activation of GABAA receptors in the LPBN induces ingestion of 0.3 M NaCl by hyperosmotic cell-dehydrated rats, suggesting that plasma levels of renin or osmolarity do not affect sodium intake after the blockade of LPBN inhibitory mechanisms with muscimol. (c) 2007 Elsevier B.V. All rights reserved.