Grant abstract:

Organic mercury compounds are known to be toxic mainly to the nervous system. Recently, the similarities between the neurological findings in mercury exposure and autism have come to attention. It has been estimated that children are exposed to a quantity of mercury that exceeds the safety guidelines in the first two years of life through thimerosal (ethylmercury salicylate) in vaccines. And, a strong association between the administration of certain vaccinations and the onset of autistic manifestations has been noted. Autism is a multi-factorial disease in the pathogenesis of which genetic, immunological, and environmental factors play a role. Brain biopsies from autistic children show degeneration and a loss of neuronal cells without any evidence of inflammation that is consistent with an apoptotic (programmed cell death) process. Mercury accumulates in the mitochondria and disrupts cell energetics. It has been shown to induce apoptosis by causing mitochondrial dysfunction in lymphocytes. No study has been published on the apoptotic effect of mercury in the nervous system. We hypothesize that mercury induces apoptosis in neuronal cells and this effect is mainly via the mitochondrial pathway. This might be more pronounced in children with autism because of genetic susceptibility. Thus, apoptosis due to mercury exposure may contribute to the pathogenesis of autism. Therefore, we intend to examine the effect of thimerosal on apoptosis induction and the signaling steps of mitochondrial pathway of apoptosis in neuronal cells. The results would clarify the effect of a mercury compound in neuronal cell death and degeneration, and provide a better understanding of the potential role of mercury exposure in the pathogenesis of autism.

Paper from the study

Yel L, Brown LE, Su K, Gollapudi S, Gupta S. Thimerosal induces neuronal cell apoptosis by causing cytochrome c and apoptosis-inducing factor release from mitochondria. Int J Mol Med. 2005 Dec;16(6):971-7. PMID: 16273274
To understand what role thimerosal might play in the onset of autistic symptoms, it is important to understand the effects of thimerosal on cells. This study examined the effects of thimerosal at different doses on neuroblastoma (cancer) cells, finding that thimerosal caused cell death even at very low doses. The study is suggestive that thimerosal can have deleterious effects on cell viability. Further study will be needed to determine if similar effects are seen with other types of cells and within living organisms. However, the findings from this type of study are an important basis for understanding how environmental factors such as mercury may play a role in triggering autism, and which biological processes they impact.