[Show abstract][Hide abstract] ABSTRACT: It has been suggested that the use of nonnutritive sweeteners (NNS) can lead to weight gain, but evidence regarding their real effect on body weight and satiety is still inconclusive. Using a rat model, the present study compares the effect of saccharin and aspartame to sucrose in body weight gain and in caloric intake. Twenty-nine male Wistar rats received plain yogurt sweetened with 20% sucrose, 0.3% sodium saccharin or 0.4% aspartame, in addition to chow and water ad libitum, while physical activity was restrained. Measurements of cumulative body weight gain, total caloric intake, caloric intake of chow and caloric intake of sweetened yogurt were performed weekly for 12 weeks. Results showed that addition of either saccharin or aspartame to yogurt resulted in increased weight gain compared to addition of sucrose, however total caloric intake was similar among groups. In conclusion, greater weight gain was promoted by the use of saccharin or aspartame, compared with sucrose, and this weight gain was unrelated to caloric intake. We speculate that a decrease in energy expenditure or increase in fluid retention might be involved.
[Show abstract][Hide abstract] ABSTRACT: Major depression is more prevalent among women than men, and progesterone might be involved in the mechanisms that generate these differences. Progesterone is clinically used for women in several reproductive events, but its antidepressant effect is unclear. Animal studies showed the interference of progesterone on depressive behaviors of rodents, but they are inconclusive, and no study compared different treatment durations. This study investigated the antidepressant effect of low doses of progesterone in male and female rats under acute or chronic administration. Male and female Wistar rats in different phases of the estrous cycle were acutely administered different doses of progesterone (0.0, 0.4. 0.8 and 1.2mg/kg) and tested in the forced swimming test (FST). The lowest dose of progesterone (0.4 mg/kg) was chronically administered during two complete estrous cycles and diestrous II female and male rats were tested in the FST. Progesterone decreased depressive-like behaviors only in chronically treated diestrous II female rats and increased immobility in male rats. This low dose of progesterone did not interfere in the hormonal cycling in female rats. Results also showed that diestrous II female rats had greater immobility than male rats in the FST. The greater immobility of diestrous II female rats shows that rats in this estrous phase present more depressive-like behaviors that may be associated with their lower serum levels of progesterone. We showed that progesterone chronically administered at low doses reverses these depressive-like behaviors and has an antidepressant effect during the diestrous II phase of the estrous cycle.