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The aim of the study was to investigate the association between blood and tissue levels of selenium and thyroid cancer through a systematic review. We searched for observational studies written in English, Spanish, and Portuguese indexed in PubMed, LILACS, and Scielo without date restriction, that evaluated the association between selenium levels in whole-blood, serum, or plasma and/or thyroid tissue and thyroid cancer, both in individuals with cancer of thyroid as in healthy individuals. Then data were extracted and analyzed. Of the 570 articles identified, five cross-sectional studies were included in the review. In one study, lower concentrations of selenium were found in whole-blood (0.543 μg/ml) and in the thyroid (0.88 μg/g) of thyroid cancer patients compared to controls. Another study showed a decrease in serum selenium concentrations in patients with follicular carcinoma and papillary types (0.077 ± 0.021 μg/ml and 0.080 ± 0.020 μg/ml, respectively). On the other hand, other studies showed no difference in plasma selenium content or glutathione peroxidase activity among patients and healthy volunteers. The available evidence on this issue is inconclusive. Additional studies are needed to elucidate the association between serum and/or tissue levels of selenium and the development of thyroid cancer.

Progesterone is a neuroactive hormone with non-genomic effects on GABAA receptors (GABAAR). Changes in the expression of GABAAR subunits are related to depressive-like behaviors in rats. Moreover, sex differences and depressive behaviors have been associated with prefrontal brain asymmetry in rodents and humans. Thus, our objective was to investigate the effect of progesterone on the GABAAR α1 and γ2 subunits mRNA expression in the right and left prefrontal cortex of diestrus female and male rats exposed to the forced swimming test (FST). Male and female rats (n = 8/group) were randomly selected to receive a daily dose of progesterone (0·4 mg·kg–1) or vehicle, during two complete female estrous cycles (8–10 days). On the experiment day, male rats or diestrus female rats were euthanized 30 min after the FST. Our results showed that progesterone significantly increased the α1 subunit mRNA in both hemispheres of male and female rats. Moreover, there was an inverse correlation between depressive-like behaviors and GABAAR α1 subunit mRNA expression in the right hemisphere in female rats. Progesterone decreased the GABAAR γ2 mRNA expression only in the left hemisphere of male rats. Therefore, we conclude that the GABAA system displays an asymmetric distribution according to sex and that progesterone, at lower doses, presents an antidepressant effect after increasing the GABAAR α1 subunit expression in the right prefrontal cortex of female rats. Copyright © 2012 John Wiley & Sons, Ltd.

In a previous study, we showed that saccharin can induce weight gain when compared with sucrose in Wistar rats despite similar total caloric intake. We now question whether it could be due to the sweet taste of saccharin per se. We also aimed to address if this weight gain is associated with insulin-resistance and to increases in gut peptides such as leptin and PYY in the fasting state. In a 14 week experiment, 16 male Wistar rats received either saccharin-sweetened yogurt or non-sweetened yogurt daily in addition to chow and water ad lib. We measured daily food intake and weight gain weekly. At the end of the experiment, we evaluated fasting leptin, glucose, insulin, PYY and determined insulin resistance through HOMA-IR. Cumulative weight gain and food intake were evaluated through linear mixed models. Results showed that saccharin induced greater weight gain when compared with non-sweetened control (p = 0.027) despite a similar total caloric intake. There were no differences in HOMA-IR, fasting leptin or PYY levels between groups. We conclude that saccharin sweet taste can induce mild weight gain in Wistar rats without increasing total caloric intake. This weight gain was not related with insulin-resistance nor changes in fasting leptin or PYY in Wistar rats.

It has been suggested that the use of nonnutritive sweeteners (NNSs) can lead to weight gain, but evidence regarding their real effect in 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.