The effects of endurance swimming and silymarin supplementation on structural remodeling and apoptotic index of adrenal cortex in pregnant rats exposed to cadmium toxicity

There are some conflicts about the advantages and disadvantages of exercise during pregnancy. The effect of heavy metals on human health is one of the most important recent concerns, especially in the pregnancy period when both mother and fetus can easily be affected. This study was conducted to investigate the effects of endurance swimming and silymarin on the structural remodeling of the adrenal cortex in pregnant rats exposed to cadmium toxicity.۷۲ pregnant Wistar rats were randomly divided into ۹ groups (n=۸) including control, sham, cadmium, silymarin, exercise, cadmium+silymarin, exercise+cadmium, exercise+silymarin+cadmium, and exercise+silymarin. Swimming exercise was performed five days a week for one hour each time. Cadmium was given to the animals as cadmium chloride dissolved in drinking water at a rate of ۴۰۰ mg/L and silymarin was administrated at a dose of ۱۰۰ mg/kg subcutaneously, ۳ times a week for ۳ weeks. Two days after parturition, mothers were euthanized and their adrenal glands were fixed in a ۱۰% buffered formalin. After tissue processing by standard paraffin embedding and Hematoxylin-Eosin and Mallory’s trichrome staining and TUNEL assay, histological, immunohistochemical and stereological studies were performed. The data were statistically analyzed by one-way ANOVA and Tukey’s post hoc using SPSS software.Cadmium toxicity significantly reduced the total volume of the adrenal gland, the adrenal cortex, and decreased the number of adrenocortical cells and promoted apoptosis in the zona glomerulosa, fasciculata and reticularis of the adrenal cortex. Swimming exercise alone could not improve these adverse effects of cadmium and even notably increased the apoptotic index of the adrenal cortex. Swimming exercise combined with the use of silymarin significantly improved the effects of cadmium, and the results of the exercise+silymarin+cadmium group were remarkably similar to the control group.According to the results of this study, it can be concluded that although endurance swimming alone cannot improve the side effects of cadmium toxicity on the adrenal cortex, but co-administration of antioxidant supplements such as silymarin can be a suitable supportive strategy for inhibition of adrenocortical damage in pregnant mothers exposed to heavy metal toxicity such as cadmium.