PINK1-PARKIN-dependent mitophagy links diphenyltin exposure to steroidogenic collapse in Rat Leydig Cells during...

Diphenyltin (DPT) is an organotin and an endocrine disruptor, impairing the male reproductive system. However, the effect of DPT on Leydig cell function during puberty remains unknown. DPT exhibits selective testicular toxicity without altering gross reproductive organ weights. In rats administered 2.5-10 mg/kg DPT from postnatal day 35 to 57, serum testosterone levels were significantly reduced at 5 and 10 mg/kg, while luteinizing hormone and follicle-stimulating hormone levels remained unchanged. Histological and immunohistochemical analyses revealed decreased Leydig cell numbers and reduced expression of steroidogenic markers (STAR, LHCGR, SCARB1, CYP11A1, and INSL3). Testicular oxidative stress was evident, with downregulated SOD1, SOD2, and CAT and elevated malondialdehyde. Autophagy markers (LC3B, Beclin1) were upregulated alongside decreased phosphorylated mTOR, as well as increased 4-hydroxynonenal, 8-hydroxy-2'-deoxyguanosine, and LC3B staining in Leydig cells, suggesting oxidative stress-induced autophagy. In vitro, adult Leydig cells displayed ROS accumulation, mitochondrial membrane potential loss, and autophagosome formation. In adult Leydig cells, DPT enhanced mitochondrial fission by upregulating DRP1 and FIS1, downregulating MFN1, and activating PINK1-PARKIN-mediated mitophagy. The fission inhibitor mdivi-1 mitigated mitochondrial fragmentation, decreased mitophagy, and partially restored steroidogenesis. These findings indicate that DPT disrupts Leydig cell function through oxidative stress, mitochondrial fission, and mitophagy, ultimately leading to testosterone suppression and compromised sperm production. Therapeutic targeting of mitochondrial dynamics may protect steroidogenic cells from toxin-induced damage.