Exposição a uma dieta rica em sal altera a resposta ao estresse diferentemente em ratos machos e fêmeas

Abstract

The average salt consumption of Brazilians is 12g per day, which is well above that recommended by the World Health Organization, as in 2023 the maximum consumption guideline was around 5g of table salt per day, which is equivalent to 2.00g of sodium daily. Salt consumption for children should be even lower and adjusted according to their energy requirements. The consumption of industrialized, processed and ultra-processed foods, especially those declared “zero sugar”, which have a high sodium content, can cause, in addition to the effects commonly observed on the cardiovascular system, a pro-inflammatory state. This pro-inflammatory state may influence the emergence of neuropsychiatric diseases including post-traumatic stress, depression and anxiety. New evidence brings salt as a behavioral modifier in rodents, opening up new possibilities for study. The objective of this thesis was to study the effects of sub-acute and subchronic exposure to a high-salt diet on the stress response in male and female rats. To this end, the thesis is presented in two chapters, the first in the format of a scientific article and the second in the form of a manuscript. In the first protocol (Article), male and female Wistar rats were exposed to a high-salt diet (NaCl 8% w/w) for 44 days from weaning. The effects of this diet on behaviors related to the phenotypes of anhedonia and depression/coping with stress were evaluated, as well as on metabolic patterns and hypothalamic leptin and ghrelin levels. In the second protocol (manuscript), the effect of sub-acute exposure (7 days) to a diet rich in salt (NaCl 8%, w/w) on behavioral parameters of coping with stress in male and female rats (45 days old) was studied. and biochemical markers of renal functionality. The results of the thesis indicate that male rats exposed subchronically (44 days) to a high-salt diet showed an active stress coping phenotype compared to control, with no evidence of anhedonia in males and females. The diet did not alter plasma biochemical parameters of renal or metabolic functionality, nor lipid peroxidation in the kidneys of rats of both sexes. Hypothalamic leptin and ghrelin levels remained unchanged. In an sub-acute exposure model (7 days), male rats showed passive coping with stress, with reduced social preference, but no change in nest building behavior. Again, there were no differences in biochemical parameters of renal functionality and lipid peroxidation in the kidney in both sexes. In both protocols, females proved to be resilient to changes caused by the diet in the face of the tests applied, with only slightly increased plasma sodium levels. It is concluded that the time of exposure to a high-salt diet alters the stress response in male rats differently, while female rats are less susceptible to these changes, regardless of the exposure time.