Hughes BW, Sealey LA and Omar Bagasra
Mechanism of Male Gender Bias in Neuroblastoma Cell Lines Exposed to Fragrances: A Link to Autism Spectrum Disorder
Autism Spectrum Disorder (ASD) is a set of complex developmental disorders whose etiology is debatable. Although the symptoms may vary from person to person, they include impairment or loss of speech, lack of empathy, and social interaction deficiency. The cases of ASD have continued to increase drastically each year, with the CDC estimating 1:68 children diagnosed, along with 4 to 5 times more prevalence in males. It is believed that ASD is caused by a combination of genetic and environmental factors, but recent studies suggest that exposure to environmental chemicals may play a critical role in its pathogenesis. Although there are no biomarkers for the disease, low levels of oxytocin and arginine vasopressin have been reported. These neuropeptides play a critical role in the development of male brains. Here we assessed the potential neurotoxic effects of everyday female fragrances in order to determine if there are morphological and immunological changes to neurons, which may suggest that they contribute to the development of ASD during gestation. In order to determine whether chemicals in fragrances have a neurotoxic effect on fetal brain development, eight cell lines derived from male and female neuroblastoma were used as an experimental model. After exposure of the cells to the particular fragrances, immunostaining was performed with oxytocin receptor antibodies to determine the up or down regulations of these receptors. Immunofluorescence showed that cells exposed to fragrances significantly reduced the percentage of OT receptor positive neurons in fetal male brain cell lines, but not the female cell lines. Separately, differences in cell structure between the cells treated with fragrances and the untreated control cells were detected using hematoxylin and eosin (H&E) staining. There were significant changes observed, such as axon elongation and thinning. These results suggest a correlation between low levels of OT and fragrance exposure, with a potential cause for ASD. Statistical analysis of the characteristics observed through H&E staining and immunocytochemistry quantitatively helped determine the effects of the fragrances on the migration, differentiation, and organization of fetal brain neurons. This may shed light on the pathogenesis of autism and male gender bias.
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