Lactate inhibited sodium intake in dehydrated rats

Francineide Fernandes-Costa; Atalia Ferreira de Lima Flôr; Valdir de Andrade Braga; Josiane Campos Cruz

doi:10.1016/j.appet.2022.106046

Lactate inhibited sodium intake in dehydrated rats

Appetite. 2022 Aug 1:175:106046. doi: 10.1016/j.appet.2022.106046. Epub 2022 Apr 22.

Authors

Francineide Fernandes-Costa¹, Atalia Ferreira de Lima Flôr¹, Valdir de Andrade Braga¹, Josiane Campos Cruz²

Affiliations

¹ Departamento de Biotecnologia, Centro de Biotecnologia, Universidade Federal da Paraíba, Brazil.
² Departamento de Biotecnologia, Centro de Biotecnologia, Universidade Federal da Paraíba, Brazil. Electronic address: josianecruz@cbiotec.ufpb.br.

PMID: 35461891
DOI: 10.1016/j.appet.2022.106046

Abstract

Recent studies have suggested that glial cells, especially astrocytes, are involved in balanced hydromineral modulation. In response to increased extracellular Na⁺ concentration, astrocytic Na_x channels are activated, promoting lactate production and release. Furthermore, previous in vitro studies have suggested that lactate and hypertonic Na + solution activate SFO GABAergic neurons involved in the salt-appetite central pathways. Here, we evaluated the role of lactate in dehydration-induced sodium and water intake. To this end, intracerebroventricular microinjection (icv) of l-lactate or α-cyano-4-hydroxycinnamic acid (α-CHCA, MCT lactate transporter inhibitor) was performed in rats subjected to 48 h of water deprivation (WD) and 1 h of partial rehydration after 48 h of WD (WD-PR). The rehydration protocol was used to distinguish the mechanisms of thirst and sodium appetite induced by WD. Then, water and sodium (0.3 M NaCl) intake were evaluated for 2 h. Our results showed that central α-CHCA induced an increase in sodium preference in WD rats. Furthermore, central lactate increased water intake but reduced sodium intake in WD-PR animals. In contrast, central lactate transporter inhibition did not change water or sodium intake in WD-PR rats. Our results suggest that lactate is involved in inhibitory mechanisms that induce sodium intake avoidance in dehydrated rats.

Keywords: Lactate; MCT; Sodium avoidance; Thirst; Water deprivation.