The present study aimed to investigate the protective effect of silymarin on maternal cadmium toxicity complications in the kidney of neonatal rats. Forty adults Wistar female rats were selected and placed with male rats for copulation. The pregnant animals were randomly divided into five groups (n = 8) including control, sham, silymarin, cadmium, and silymarin + cadmium. The animals received 400 mg L-1 cadmium and 100 mg kg-1 silymarin (subcutaneously, three days per week, three weeks). Two-day neonates were dissected and their right kidneys were fixed in 10.00% buffered formalin solution and processed by standard paraffin embedding. Tissue sections were stained by hematoxylin and eosin and analyzed histologically and stereologically. The data were statistically analyzed by SPSS using a one-way ANOVA test and Tukey's post-hoc. The results showed that silymarin significantly increased the neonatal rats' weight compared to the control group. Cadmium significantly decreased the weight of neonatal rats' kidneys. The results of histological studies indicated that cadmium caused subacute glomerulosclerosis, severe damage to urinary tubules such as tubular necrosis, and severe hyperemia in the medulla, but silymarin could preserve these complications. Stereological results revealed that cadmium decreased the total volume of kidney, medulla, and proximal and distal tubules and increased interstitial tissue and indicated the protective effects of silymarin on maternal cadmium toxicity complications in the kidney tissue of neonatal rats. It can be concluded that the administration of silymarin during pregnancy may be used as a useful and effective way of protecting the maternal cadmium toxicity complications in the kidney tissue of neonatal rats.
