Efeito da restrição calórica e da rapamicina sobre o envelhecimento ovariano em camundongos

Abstract

Caloric restriction (CR) is known to increase the preservation of the ovarian reserve. Likewise, rapamycin has been shown to have similar effects to CR regarding the ovarian reserve. The aim of this study was to evaluate the effects of rapamycin and caloric restriction on follicular reserve, oxidative stress, ovarian gene expression and also on glucose metabolism in mice. Thirty-six female mice of C57BL/6 lineage maintained with standard diet, water ad libitum and under controlled light and temperature conditions were used. The mice were alocated into 3 groups of 12 animals each (control group, group treated with intraperitoneal rapamycin every 2 days at a dose of 4mg/kg body weight and the group submitted to CR of 30% compared to the control group). At 85 days of treatment, an insulin tolerance test (ITT) and glucose tolerance test (GTT) were performed. At 93 days of treatment the mice were euthanized, and the ovaries were collected, one for histological analysis, and the other for gene expression and analysis of reactive oxygen species (ROS). Statistical analyzes were performed using Graphpad Prism 6 software. Values of P<0.05 were considered significant. There was no difference in consumption and weight gain between the control and rapamycin (P>0.05). In the ITT, mice of the rapamycin were more resistant to insulin whereas those of the CR had higher insulin sensitivity (P=0.003). In the GTT, from females of the rapamycin group were more intolerant to glucose when compared with RC and control groups (P=0,04). Females of the rapamycin group had higher levels of ROS when compared to the control group (P<0.05). The females, CR and rapamycin had a higher number of primordial follicles (P=0.02 and 0.04) and a lower number of primary follicles (P<0.001) and both had greater expression of the transcription factor Foxo3a (P=0.01). CR mice had lower level of expression of Akt1 than those of rapamycin (P<0.05). Therefore, females of rapamycin and CR had a greater ovarian reserve and higher expression of Foxo3a, but females of rapamycin were more intolerant to glucose whereas those of CR were more sensitive to insulin and there was no difference in weight gain and consumption of the females of the rapamycin. This indicates that the expression of Foxo3a was a common factor between the treatments and that resulted in reduced activation of primordial follicles.