AT(1) receptor blockade in the lateral parabrachial nucleus reduces the effects of muscimol on sodium intake
The blockade of the lateral parabrachial nucleus (LPBN) with GABA(A) receptor agonist muscimol induces robust hypertonic NaCl and water intake by rats. In the present study we investigated the effects of previous injections of losartan (AT(1) angiotensin receptor antagonist) into the LPBN on 0.3 M N...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2011 |
| País: | Brasil |
| Institución: | Universidade Estadual Paulista (UNESP) |
| Repositorio: | Repositório Institucional da UNESP |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.unesp.br:11449/16342 |
| Acceso en línea: | http://dx.doi.org/10.1016/j.brainres.2011.06.004 http://hdl.handle.net/11449/16342 |
| Access Level: | acceso abierto |
| Palabra clave: | GABA receptor Angiotensin II Losartan Sodium appetite Thirst Lateral parabrachial nucleus |
| Sumario: | The blockade of the lateral parabrachial nucleus (LPBN) with GABA(A) receptor agonist muscimol induces robust hypertonic NaCl and water intake by rats. In the present study we investigated the effects of previous injections of losartan (AT(1) angiotensin receptor antagonist) into the LPBN on 0.3 M NaCl and water intake induced by muscimol injected bilaterally in the same area in fluid replete rats and in rats treated with the diuretic furosemide combined with a low dose of the angiotensin-converting enzyme inhibitor captopril injected subcutaneously. Male Wistar rats with stainless steel cannulas implanted bilaterally into the LPBN were used. Bilateral injections of muscimol (0.5 nmol/0.2 mu l, n=8) into the LPBN in fluid replete rats induced 0.3 M NaCl intake (23.4 +/- 4.1 vs. saline: 0.4 +/- 0.4 ml/3 h) and water intake (9.3 +/- 1.9 vs. saline: 0.7 +/- 0.4 ml/3 h) and pre-treatment of the LPBN with losartan (50 mu g/0.2 mu l) reduced 0.3 M NaCl intake (3.3 +/- 2.5 ml/3 h) and water intake (4.0 +/- 2.9 ml/3 h) induced by muscimol. In rats treated with furosemide + captopril, pretreatment with losartan into the LPBN attenuated the increase of 0.3 M NaCl intake produced by muscimol (12.8 +/- 5.3, vs. saline + muscimol: 36.7 +/- 6.7 ml/3 h) without changing water intake. Therefore, the results suggest that deactivation of LPBN inhibitory mechanisms by muscimol injections into the LPBN is facilitated by endogenous angiotensin II acting on AT(1) receptors in the LPBN, which drives rats to ingest large amounts of hypertonic NaCl. (C) 2011 Elsevier B.V. All rights reserved. |
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