Neonatal exposure of male rats to nonylphenol has no effect on the reproductive tract

P. C. Lee (1998, Endocrine 9, 105-111) has reported that neonatal exposure of SD rats to nonylphenol (NP; 8 mg/kg/day) by daily intraperitoneal (ip) injection in DMSO results in decreased ventral prostate and epididymides weights, and delayed testes descent, at post natal day (pnd) 31. These effects were surprising given that similar effects were not reported in an earlier multigeneration study of NP. We have repeated the central experiment described by Lee and were unable to confirm the effects reported. Alpk (Wistar derived) rats were exposed to NP (8mg/kg/day by ip injection in either arachis oil or DMSO) from pnd 1-10 and assessed on pnd 34-36, No significant effects on animal body weights were observed. The weights of the epididymides, seminal vesicles, testes, and ventral prostate were unaffected using either vehicle. Testes descent proceeded normally, with both test and control testes fully descended by pnd 29, Possible reasons for this divergence in findings for NP are discussed.