P-Nonylphenol (p-NP) as a non ionic surfactant is used in many industries such as pesticides, cosmetics, detergents and so on. Our previous study showed that the p-NP causes reduction in viability of the rats Bone Marrow Mesenchymal Stem cells (MSCs). The aim of the present study was to investigate the mechanism of the cell death due to p-NP exposure. The cells, after 3rd passage were treated with 100μM p-NP for a period of 36 hrs, then using TUNEL, caspase and comet assay as well as fluorescent dye like Hochest, acridine orange and monodansylcadaverin (MDC) staining the mechanism of cell death was studied. The results of this study showed that the p-NP treated cells were TUNEL positive and also, activated caspase-3 enzyme in their cytoplasm was visualized. Hochest staining showed chromatin condensation and nuclei breakage, at which the nuclear breakage was further confirmed by comet assay. In addition, staining the cells with acridine orange revealed that the cytoplasm of the treated cells contained numerous vesicles. Furthermore, staining of the cells with MDC showed the presence of the double layer autophagic vacuoles. In conclusion, the induced cell death due to p-NP toxicity was determined to be caspase dependent apoptosis as well as autophagy.
