NEUROCHEMICAL CHARACTERIZATION OF THE BRAIN GROUPS ACTIVATED AFTER BLOOD VOLUME EXPANSION

A. GODINO; J. ANTUNES-RODRÍGUES; L. VIVAS

Riberao Preto, Brasil

Congreso; XXXVIII Congreso da Sociedade Brasileira de Fisiologia SBFis e Congresso da Assoiaçao Latino-Americana de Ciências Fisiológicas; 2003

Previous evidence suggests the contribution of noradrenergic and serotonergic pathways in the brain systems that control body fluid and electrolytic homeostasis. The aim of the present work was to identify the catecholaminergic and serotonergic groups of neurons activated or Fos immunoreactive (Fos-ir), following blood volume expansion (BVE). Methods: Male Albino rats were volume expanded, via jugular vein, with isotonic saline, (2 ml/100 b.wt. for 60 seconds) or given sham infusion. Ninety minutes later the animals were subject to a combined immunohistochemical detection of Fos and serotonin (5HT) or Fos and Tyrosine hydroxylase (TH), as a marker of catecholaminergic neurons. Results: Compared to control animals we found a significant increase in the number of Fos-ir neurons in the anteroventral third ventricle (AV3V) region, parvocellular subdivisions of the paraventricular hypothalamus nucleus (PVN), supraoptic nucleus (SON), central amygdala (CeA), lateral parabrachial nuclei (LPBN), locus coeruleus (LC), dorsal raphe nucleus (DRN), and ventrolateral medulla (VLM), after blood volume expansion. Moreover, within the AV3V, RVLM, CVLM, PVN, NTS and LC we observed a higher percentage of double immunolabeled cells Fos-TH in relation to control animals. Besides, along the raphe system the DRN showed a greater number of double immunoreactive cells Fos-5HT, after BVE. In conclusion, the present results support the involvement of serotonergic pathways within the raphe system and forebrain and brainstem catecholaminergic circuits in the reflex response to volume reestablishment. A continuación se adjunta abstract por no disponer de la última versión del power point.