Effects of Thimerosal on Cerebellum Tissue and Neurodevelopmental Disorders Related Behaviors in Rats

Background: Thimerosal (THIM) is one of the most important and inexpensive preservatives in many pharmaceutical and health products. The current knowledge on the impact of this substance on fetal neurodevelopment and incidence of behavioral and tissue defects is very controversial. Here we investigated neonatal administration of THIM on behaviors and cerebellar tissue, which are important in movement, balance, and sensory integration and which are more typically altered in Autism spectrum disorder (ASD) ASD. Methods: The experiments were directed on 40 young adult male and female Wistar rats, in groups of 10, which were randomly divided into four groups: groups 2 & 1: male and female experimental groups (which received THIM (300μg Hg/kg), Intramuscular injections (im) on postnatal days (15 ,11 ,9 ,7) and groups 3 4 &: male and female control groups (which received saline in the same pattern). On the fourth week after birth, rats were examined with open field test and in the 8th post natal week, three-chamber paradigm test was conducted on the animals. After the end of the behavioral tests, histological studies wer e perfromed. Results: Adult male and female rats, which were exposed to THIM, demonstrated impairments of locomotors activity and their social affiliation, social memory, and novelity reduced (p<0.001). During freezing, grooming, as the stereotyped behavior, increased significantly (p<0.05). The results of histological studies showed a significant decrease in the number of purkinje cells in the groups treated with THIM (p<0.001). Conclusion: These data document that probably the early postnatal THIM administration causes lasting neurobehavioral and histological impairments and these conditions could contribute to neurodevelopmental disorders.