Investigating the Effects of Maternal Separation on Hypothalamic-Pituitary-Adrenal Axis and Glucose Homeostasis under Chronic Social Defeat Stress in Young Adult Male Rat Offspring

Effects of early-life stress followed by access to stevia or sucralose during adolescence on weight gain, glycemia, and anxiety-related behaviors in male and female rats

Early-life stress and subsequent high-calorie diets during adolescence are known to be risk factors for developing metabolic and psychological disorders. Although non-nutritive sweeteners such as stevia and sucralose have been a useful alternative to reduce sugar consumption, the effects of prolonged consumption of these sweeteners on metabolism and behavior in adolescents remain unclear. Here, we evaluated the effects of early-stress followed by access to stevia or sucralose during adolescence on weight gain, glycemia, and anxiety-related behaviors in male and female rats. During postnatal days (PNDs) 1-21, pups were separated twice a day, for 180 min each time, from their dam nest while non-separated pups served as controls. The pups were weaned, separated by sex and randomly distributed into the stevia, sucralose and water conditions. During PNDs 26-50, two bottles containing water and stevia or sucralose were placed in the animal home-cages, and body weight and blood glucose measures were scored. On PNDs 50 and 51, behavioral measures were obtained in the open-field test. Results showed that male rats consuming stevia reduced body weight gain, blood glucose and increased locomotion. Early-stress led to low blood glucose and alterations in anxiety and locomotion-related behaviors in a sex-dependent manner. Moreover, sucralose access during adolescence reversed the effects of early-stress on anxiety-related behaviors in female rats. The results suggest that the consumption of stevia and sucralose could be an alternative for the replacement of sugar-sweetened beverages, especially in adolescents who have had adverse early-life experiences.

Oral exposure to an acceptable daily intake dose of aspartame induced a delayed proinflammatory cytokine response in the cerebrospinal fluid of rats

This study aimed to investigate the effect of exposure to aspartame (ASP) at safe levels on proinflammatory cytokines in the cerebrospinal fluid (CSF) of rats. Sprague Dawley rats were sacrificed after 1, 2, 4 or 8 week(s) of continuous exposure to ASP (40 mg/kg body weight). Serum, CSF and brain tissue samples were prepared, and the levels of the IL-1β, IL-6 and TNF-α were analyzed by ELISA. In serum, the levels of all three cytokines showed a two-phase alteration, a decrease followed by an increase in the ASP group. In the brain, their levels increased from the second or fourth week compared with the control group. In CSF, the levels of these cytokines showed a similar change to that in brain tissue, but the increase appeared at a later time point. For each cytokine, there was a significant positive correlation between its levels in serum, brain tissue and CSF. This is the first discovery that ASP exposure increased the levels of proinflammatory cytokines in CSF in rats, which emerged later than in blood and brain tissue. This study suggests the necessity of conducting related clinical studies to evaluate potential neuroinflammatory effects induced by chronic ASP exposure through CSF analysis.

Epigenetic modifications and fetal programming: Molecular mechanisms to control hypertension inheritance

Cardiovascular diseases (CVD) are the number 1 cause of death in the United States and hypertension is a highly prevalent risk factor for CVD. It is estimated that up to 50 % of the hypertensive trait is genetically inherited while the other 50 % is determined by modifiable factors involving lifestyle, behaviors, and the environment. Interestingly, the hypertensive trait is induced or inhibited by epigenetic modifications modulated by modifiable factors. This review focused on the underlying mechanisms of stress, sleep deprivation, obesity and sedentarism as key players for epigenetic modifications contributing to the development of the hypertensive trait and, on the other hand, how epigenetic modifications induced by physical exercise and healthier habits may contribute to overturn and prevent the inheritance of hypertension trait. Furthermore, adversities during gestation and perinatal life also increase the risk for hypertension and CVD later in life, which can perpetuate the inheritance of the hypertensive trait whereas healthier habits during gestation and lactation may counteract fetal programming to improve the cardiovascular health of the progeny. Therefore, it is promising that a healthier lifestyle causes long-lasting epigenetic modifications and is transmitted to the next generation, strengthening the fight against the inheritance of hypertension.