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Whole body sodium depletion modifies AT 1 mRNA expression and serotonin content in the dorsal raphe nucleus
Author(s) -
Porcari Cintia Yamila,
Araujo Iracema Gomes,
UrzedoRodrigues Lilia,
De Luca Laurival Antonio,
Menani José Vanderlei,
Caeiro Ximena Elizabeth,
Imboden Hans,
AntunesRodrigues José,
Reis Luís Carlos,
Vivas Laura,
Godino Andrea,
Mecawi André Souza
Publication year - 2019
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/jne.12703
Subject(s) - dorsal raphe nucleus , endocrinology , medicine , serotonergic , chemistry , serotonin , receptor , raphe nuclei , subfornical organ , 5 ht receptor , biology , angiotensin ii
Angiotensin II ( Ang II ) acts on Ang II type 1 ( AT 1) receptors located in the organum vasculosum and subfornical organ ( SFO ) of the lamina terminalis as a main facilitatory mechanism of sodium appetite. The brain serotonin (5‐ HT ) system with soma located in the dorsal raphe nucleus ( DRN ) provides a main inhibitory mechanism. In the present study, we first investigated the existence of Ang II AT 1 receptors in serotonergic DRN neurones. Then, we examined whether whole body sodium depletion affects the gene expression of the AT 1a receptor subtype and the presumed functional significance of AT 1 receptors. Using confocal microscopy, we found that tryptophan hydroxylase‐2 and serotonin neurones express AT 1 receptors in the DRN . Immunofluorescence quantification showed a significant reduction in 5‐ HT content but no change in AT 1 receptor expression or AT 1/5‐ HT colocalisation in the DRN after sodium depletion. Whole body sodium depletion also significantly increased Agtr1a mRNA expression in the SFO and DRN . Oral treatment with the AT 1 receptor antagonist losartan reversed the changes in Agtr1a expression in the SFO but not the DRN . Losartan injection into either the DRN or the mesencephalic aqueduct had no influence on sodium depletion‐induced 0.3 mol L ‐1 NaCl intake. The results indicate the expression of Agtr1a mRNA in the DRN and SFO as a marker of sodium depletion. They also suggest that serotonergic DRN neurones are targets for Ang II . However, the function of their AT 1 receptors remains elusive.