Cartap hydrochloride induces dose-dependent oxidative stress and HSP70 overexpression in testicular tissue of Wistar rats: protective effect of α-tocopherol.

Cartap hydrochloride is a widely used nereistoxin-derived insecticide; however, the mechanistic basis of its effects on the male reproductive system remains poorly characterised. We have previously reported that subacute oral exposure to cartap hydrochloride reduces sperm count, sperm viability and sperm membrane integrity, and lowers plasma testosterone concentrations in adult male Wistar rats, with partial amelioration by α-tocopherol. The present study examined the biochemical and molecular changes accompanying those phenotypic outcomes in testicular tissue from the same experimental model. Forty-two adult male Wistar rats were divided into seven groups (n=6): control, vehicle control, α-tocopherol (100mg/kg), cartap hydrochloride (16.25 and 32.5mg/kg), and corresponding co-treatment groups, treated orally for 28 days. Body weight, absolute and relative testicular weight, testicular lipid peroxidation, superoxide dismutase, catalase, reduced glutathione and glutathione S-transferase were measured (n=6); HSP70 mRNA expression was quantified by real-time qPCR using the 2^(-ΔΔCt) method (n=3). Percent body weight gain was significantly reduced at 32.5mg/kg (P < 0.001), whereas absolute testicular weights were unchanged. Cartap produced significant (P < 0.001) dose-dependent increases in lipid peroxidation with concomitant depletion of antioxidant enzymes, and marked upregulation of HSP70 mRNA (8.17- and 27.70-fold at the low and high doses). α-Tocopherol co-administration attenuated these biochemical and molecular changes at the lower dose but not at the higher dose. These findings characterise the oxidative and transcriptional response accompanying cartap-induced reproductive toxicity and identify HSP70 as a sensitive marker of testicular biological response to cartap exposure.