Silver nanoparticles induced testicular damage targeting NQO1 and APE1 dysregulation, apoptosis via Bax/Bcl-2 pathway, fibrosis via TGF-β/α-SMA upregulation in rats

In medicine, silver nanoparticles (AgNPs) are employed often. They do, however, have negative impacts, particularly on the reproductive organs. This research aimed to assess AgNP impact on the testis and the possible intracellular mechanisms to induce testicular deteriorations in rats at various concentrations and different time intervals. Sprague Dawley rats (n = 40) were allocated into four equal groups: the control one, and three other groups injected intra-peritoneally with AgNP solution 0.25, 0.5, and 1 mg/kg b.w. respectively for 15 and 30 days. Our findings revealed that AgNPs reduced body and testicular weights, estradiol (E2) and testosterone (T) hormone levels, and sperm parameters while elevating the nitric oxide and malondialdehyde levels with inhibition of reduced glutathione contents in testicular tissue. Interestingly, AgNPs significantly upregulated the testicular inducible nitric oxide synthase, B cell lymphoma 2 (Bcl-2)-associated X, transforming growth factor, and alpha-smooth muscle actin (α-SMA) expression levels. However, apurinic/apyrimidinic endo deoxyribonuclease 1 (APE1), NAD (P) H quinone dehydrogenase 1 (NQO1), and Bcl-2 expression levels were all downregulated indicating exhaustion of body antioxidant and repairing defense mechanisms in testicles in comparison with the control rats. Various histological alterations were also detected which dramatically increased in rats sacrificed after 30 days such as loss of the lining cells of seminiferous tubules with no spermatozoa and tubular irregularities associated with thickening of their basement membranes. Immunolabeling implicated in the apoptotic pathway revealed a negative expression of Bcl-2 and marked immunoreactivity for caspase-3 after 30 days of AgNP treatment in comparison to the control rats. To our knowledge, there have been no previous publications on the role of the α-SMA, APE1, and NQO1 genes in the molecular pathogenesis of AgNP testicular cytotoxicity following AgNP acute and chronic exposure. Graphical Abstract: [Figure not available: see fulltext.].