Dose-dependent reproductive toxicity of sodium benzoate in male rats: Inflammation, oxidative stress and apoptosis

The synthetic food preservative sodium benzoate (SB) is widely used in both food and pharmaceutical industries. A growing body of evidence highlights the adverse effects of SB on human health; however, effect of the prolonged intake of SB on the reproductive system is not fully elucidated. The current study investigates the effect of different doses of SB (0-1000 mg/kg BW) on the reproductive system of male rats administered oral SB for 90 consecutive days. Results revealed that increasing doses of SB significantly altered the weight of reproductive organs, decreased sperm count and motility and enhanced the percentage of abnormal sperms. This was concomitant with significant decline in plasma testosterone and FSH levels, increase in plasma LH and decrease in the activities of 17β-HSD and 17-KSR enzymes in the testes. Inflammation and oxidative stress were induced as indicated by the significant increase in TNF-α and IL-6 levels, inhibition of antioxidant enzymes activity and levels of GSH, increase in the levels of NO and TBARS and enhanced protein expression of mtTFA and UCP2 in the testes. Interestingly, p53 expression and caspase-3 activity were upregulated in the testes suggesting induction of apoptosis. Histopathological examination of the testes confirmed apoptosis and revealed degenerative alterations of the testes' architecture and perturbation of spermatogenesis. Based upon these findings, the no-observed-adverse-effect level of SB on the reproductive system was determined to be less than 1 mg/kg BW/day, highlighting the risks of long-term exposure to low as well as high doses of SB on male reproductive health.

Keywords: Sodium benzoate; apoptosis, testes histology; caspase-3; cytokines; male reproductive system; mitochondrial transcription factor A; oxidative stress; p53; uncoupling protein 2.