Protective Effects of Sesame Seed Oil Nanoemulsion Against Cypermethrin‐Induced Testicular Toxicity Through Modulation of Oxidative Stress and Apoptotic Signaling in Rats

Cypermethrin (CYP) is a widely used insecticide. This study investigated the protective effects of sesame seed oil nanoemulsion (SEONE) against CYP-induced testicular toxicity in 60 rats. Parameters investigated included body and reproductive organ weights, semen quality, oxidative stress markers (catalase, superoxide dismutase, reduced glutathione, malondialdehyde, reactive oxygen species, reproductive hormones, and expression of apoptotic and antiapoptotic genes [p53, Bax, caspase-3, caspase-9, Bcl-2]), along with structural evaluation of testes. Compared to controls, CYP reduced body weight (-12%) and reproductive organ weights (-18% to -22%), decreased sperm count (5.62 ± 0.74 × 10⁶) and motility (49.32% ± 2.89%), while increasing abnormal sperm (18.22% ± 1.24%). CYP administration induced oxidative damage, indicated by decreased activities of catalase (-46%) and superoxide dismutase (-55%), reduced levels of reduced glutathione (37.3% ± 2.1%), and elevated malondialdehyde (61.7% ± 23.6%), ROS (64.2% ± 3.2%), and hydrogen peroxide (145.3% ± 3.4%). Testosterone, luteinizing, and follicle-stimulating hormones levels were significantly decreased (-52% to -62%) in the CYP-treated group. These alterations were accompanied by significant upregulation of apoptotic genes p53, Bax, caspase-3, and caspase-9 and marked downregulation of the antiapoptotic gene Bcl-2. SEONE provided markedly better protection against CYP-induced testicular damage than unprocessed SEO (p < 0.05). Its administration resulted in higher body and reproductive organ weights, improved semen parameters, and restored testicular histology and ultrastructure, producing outcomes that closely resembled those of the control group. The superior performance of SEONE is likely linked to its improved physicochemical properties and multifaceted antioxidant and antiapoptotic protective actions. In conclusion, SEONE effectively mitigates CYP-induced testicular toxicity in rats, supporting its potential as a protective intervention against pesticide-induced reproductive damage.