Triptolide induces Sertoli cell apoptosis in mice via ROS/JNK-dependent activation of the mitochondrial pathway and inhibition of Nrf2-mediated antioxidant response

Acta Pharmacol Sin. 2018 Feb;39(2):311-327. doi: 10.1038/aps.2017.95. Epub 2017 Sep 14.


Triptolide (TP), an oxygenated diterpene, has a variety of beneficial pharmacodynamic activities but its clinical applications are restricted due to severe testicular injury. This study aimed to delineate the molecular mechanisms of TP-induced testicular injury in vitro and in vivo. TP (5-50000 nmol/L) dose-dependently decreased the viability of TM4 Sertoli cells with an IC50 value of 669.5-269.45 nmol/L at 24 h. TP (125, 250, and 500 nmol/L) dose-dependently increased the accumulation of ROS, the phosphorylation of JNK, mitochondrial dysfunction and activation of the intrinsic apoptosis pathway in TM4 cells. These processes were attenuated by co-treatment with the antioxidant N-acetyl cysteine (NAC, 1 mmol/L). Furthermore, TP treatment inhibited the translocation of Nrf2 from cytoplasm into the nucleus as well as the expression of downstream genes NAD(P)H quinone oxidoreductase1 (NQO1), catalase (CAT) and hemeoxygenase 1 (HO-1), thus abrogating Nrf2-mediated defense mechanisms against oxidative stress. Moreover, siRNA knockdown of Nrf2 significantly potentiated TP-induced apoptosis of TM4 cells. The above results from in vitro experiments were further validated in male mice after oral administration of TP (30, 60, and 120 mg·kg-1·d-1, for 14 d), as evidenced by the detected indexes, including dose-dependently decreased SDH activity, increased MDA concentration, altered testicle histomorphology, elevated caspase-3 activation, apoptosis induction, increased phosphorylation of JNK, and decreased gene expression of NQO1, CAT and HO-1 as well as nuclear protein expression of Nrf2 in testicular tissue. Our results demonstrate that TP activates apoptosis of Sertoli cells and injury of the testis via the ROS/JNK-mediated mitochondrial-dependent apoptosis pathway and down-regulates Nrf2 activation.

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Caspase 3 / metabolism
  • Cytochromes c / metabolism
  • Diterpenes / adverse effects*
  • Epoxy Compounds / adverse effects
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Male
  • Membrane Potential, Mitochondrial / drug effects
  • Mice, Inbred ICR
  • NF-E2-Related Factor 2 / metabolism
  • Phenanthrenes / adverse effects*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Reactive Oxygen Species / metabolism
  • Sertoli Cells / drug effects*
  • Sertoli Cells / pathology
  • Signal Transduction / drug effects
  • Testis / drug effects*
  • Testis / pathology
  • bcl-2-Associated X Protein / metabolism


  • Bax protein, mouse
  • Diterpenes
  • Epoxy Compounds
  • NF-E2-Related Factor 2
  • Nfe2l2 protein, mouse
  • Phenanthrenes
  • Proto-Oncogene Proteins c-bcl-2
  • Reactive Oxygen Species
  • bcl-2-Associated X Protein
  • triptolide
  • Cytochromes c
  • JNK Mitogen-Activated Protein Kinases
  • Casp3 protein, mouse
  • Caspase 3