• Lucia F Franchini, Alan Kim Johnson, José de Olmos, and Laura Vivas.
• Instituto de Investigación Médica Mercedes y Martin Ferreyra, 5000 Córdoba, Argentina.
• Am. J. Physiol. Regul. Integr. Comp. Physiol. 2002 Jan 1; 282 (1): R235-43.

AbstractWe evaluated serotonergic hindbrain groups of cells for their involvement in the generation and inhibition of sodium appetite. For that purpose, we analyzed the number of Fos-immunoreactive (Fos-ir) cells and double-labeled Fos-serotonin (5-HT)-ir neurons within different nuclei of the hindbrain raphe system and the area postrema (AP). Sodium depletion and sodium appetite were induced by peritoneal dialysis. Twenty-four hours after peritoneal dialysis, a 2% NaCl solution intake test was given to peritoneal dialyzed animals [PD-with access (PD-A) group] and to control dialyzed animals [CD-with access (CD-A) group]. Two additional groups of animals received either peritoneal dialysis or control dialysis but were not given access to the 2% NaCl [CD-no access (CD-NA) group or PD-no access (PD-NA) group]. The number of Fos-ir neurons within different nuclei of the raphe system was increased in spontaneous and induced sodium ingestion of CD-A and PD-A groups compared with the CD-NA and PD-NA groups. The PD-NA group had significantly fewer double-labeled cells along the raphe system compared with the animals in near-normal sodium balance (CD-NA and CD-A) or in the process of restoring sodium balance by consuming NaCl (PD-A). The AP of the PD-A group showed a significant increase in the number of Fos-ir and Fos-5-HT-ir cells compared with the PD-NA and CD groups. Our results suggest that serotonergic pathways with cell bodies in the AP and the raphe system are involved in the control of sodium appetite.

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