Age and sex influence the response in lipid metabolism of dehydrated Wistar rats | Scientific Reports

The first dinosaurs had metabolisms akin to today’s birds. “Dinosaurs included remarkably swift and agile animals,” says Derek Briggs.


Scientific Reports

volume 12, Article number: 9164 (2022)
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Aging is associated a decrease in thirst sensation, which makes old people more susceptible to dehydration. Dehydration produces energy metabolism alterations. Our objective was to determinate the effect of water deprivation (WD) in the lipid metabolism of old male and female rats. Here we show that in the state of WD, aging and sex alters retroperitoneal white adipose tissue (R-WAT) weight of rats, WD old female rats had more lipolysis products than old male rats, a sexual dimorphism in the hormonal response related with metabolism of the adipose tissue of old rats during WD, the expression of P-para mRNA in R-WAT did not present any alteration in animals submitted to WD, the expression of Aqp7 mRNA in R-WAT is altered by WD, age, and sex. Also, WD stimulated an increase in the plasma concentration of oxytocin and the expression of mRNA of the oxytocin receptors in R-WAT.

Aging is associated with decrease in thirst sensation1. Hyperosmolarity and dehydration alter energetic metabolism2. Thus, hypertonicity condition with mannitol decrease plasma free fatty acids (FFA) in vivo and decreased insulin release in vitro2. Additionally, in male Sprague-Dawley rats deprived of water and food for 24, 48, and 72 h showed more loss of body weight and less increase of plasma FFA than fasted rats, but no differences in blood glucose levels and insulin were observed2. In addition, Levy and Stevens observed that plasma hyperosmolality stimulates leptin secretion acutely, which happen by a vasopressin-adrenal mechanism3.

During dehydration, the neurohypophyseal hormones, vasopressin, and oxytocin (OT) are released. The increase of these hormones helps to kept hydromineral homeostasis4. However, OT has been associated with metabolic effects and weight loss in diet-induced obese animals by reducing food intake and visceral fat mass5,6. Chronic central OT infusion increases adipose tissue lipolysis and fatty acid β-oxidation but reduces glucose intolerance and insulin resistance7. Furthermore, OT increases the expression of stearoyl-coenzyme A desaturase 1 and N-oleoyl-phosphatidyl-ethanolamine which are oleoylethanolamide productor, a known PPAR-alpha activator7. Furthermore, in young healthy men, OT reduces reward-related energy intake and glucoregulatory response to food intake8.

OT has a dual action mechanism on metabolism9. OT concentration below 10–8 M, which is basal plasma OT level, stimulates glucose incorporation into glycogen, promotes H2O2 production, and inhibits hormone-stimulated lipolysis. However, OT concentration higher than 10–8 M activates glycogenolysis and glucose transport system, which is additive to insulin effect, suggesting different mechanism of action for two hormones. Moreover, the inhibition of hormone-stimulated lipolysis is diminished, thus OT itself becomes lipolytic9.