Dose-dependent cochlear and vestibular toxicity of trans-tympanic cisplatin in the rat.

In vivo studies are needed to study cisplatin ototoxicity and to evaluate candidate protective treatments. Rats and mice are the preferred species for toxicological and pharmacological pre-clinical research, but systemic administration of cisplatin causes high morbidity in these species. We hypothesized that trans-tympanic administration of cisplatin would provide a good model for studying its auditory and vestibular toxicity in the rat. Cisplatin was administered by the trans-tympanic route in one ear (50µl, 0.5-2mg/ml) of rats of both sexes and two different strains. Cochlear toxicity was corroborated by histological means. Vestibular toxicity was demonstrated by behavioral and histological analysis. Cisplatin concentrations were assessed in inner ear after trans-tympanic and i.v. administration. In all experiments, no lethality and only scant body weight loss were recorded. Cisplatin caused dose-dependent cochlear toxicity, as demonstrated by hair cell counts in the apical and middle turns of the cochlea, and vestibular toxicity, as demonstrated by behavioral analysis and hair cell counts in utricles. High concentrations of cisplatin were found in the inner ear after trans-tympanic administration. In comparison, i.v. administration resulted in lower inner ear concentrations. We conclude that trans-tympanic administration provides an easy, reproducible and safe model to study the cochlear and vestibular toxicity of cisplatin in the rat. This route of exposure may be useful to address particular questions on cisplatin induced ototoxicity and to test candidate protective treatments.

Environmental concentration of nonylphenol alters the development of urogenital and visceral organs in avian model.

Nonylphenol (NP) is an endocrine disruptor with harmful effects including feminization and carcinogenesis on various organisms. This substance is a degradation product of nonylphenol ethoxylates (NPEO) that is used in several industrial and agricultural processes. In this paper, we examined the assessment of NP exposure on chick embryo development, using a concentration consistent with the environmental concentrations of NP. With this aim, NP (between 0.1 and 50 µg/egg) was injected into the yolk of egg through a small needle hole in the shell. We report the effect of NP on chick reproductive system development although the effect we observed is lower than those observed by exposition to other endocrine disruptors. However, histological analysis highlighted a decrease of intraluminal seminiferous surface area in 64.12% of case (P=0.0086) and an heterogeneous organization of the renal tubules when 10 µg/egg were injected. Moreover, an impairment of liver development with an abnormal bile spillage was observed when higher concentration of NP was injected (50 µg/egg).