It is well known that in mice the extension in lifespan by rapamycin is sexually dimorphic, in that it has a larger effect in females than males. In a previous study we showed that in male C57BL6 mice, rapamycin had less profound effects in both gene expression and liver metabolites when compared to dietary restriction (DR), but no data was available in females. Because recent studies showed that rapamycin increases longevity in a dose dependent manner and at every dose tested the effect remains larger in females than in males, we hypothesized that rapamycin should have a stronger effect on gene expression in females, and this effect could be dose dependent. To test this hypothesis, we measured the changes in liver gene expression induced by rapamycin (14 ppm) with a focus on several genes involved in pathways known to play a role in aging and that are altered by DR. To investigate whether any effects are dose dependent, we also analyzed females treated with two additional doses of rapamycin (22 and 42 ppm). We observed striking differences between male and female in gene expression at 14 ppm, where females have a larger response to rapamycin than males, and the effects of rapamycin in females resemble what we observed under DR. However, these effects were generally not dose dependent. These data support the notion that female mice respond better to rapamycin, and at least with the set of genes studied here, the effect of rapamycin in females resemble the effect of DR.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-0909-7) contains supplementary material, which is available to authorized users.

Vitamin A overdose is a common occurrence due to food fortification and ingestion of vitamin A supplements. Vitamin A is a nutrient that possesses known and potential effects on general health and the immune response. This research work is an in vivo investigation of the effects of administration of vitamin A above dietary requirements on some organs involved in immunity, vitamin A storage, and metabolism in healthy male rats. A total of 60 young adult male Wistar rats were equally divided into three groups. Rats in the two test groups were orally administered with vitamin A at different concentrations (8000 and 15 000 IU kg -1 body weight) for 21 days, while the control rats did not receive any supplementation. Weekly body weights and weights of the liver, kidney, spleen, and thymus were measured. Histological evaluations were carried out on the liver, kidney, thymus, and Peyer's patches. Findings show that vitamin A did not significantly affect body and organs' weights, except for a significant decrease of spleen weights for both experimental groups. Vitamin A was found to lead to some changes in the histology of the tested organs. This is the first study of its kind and sets a base for future studies.