Thimerosal is used as a preservative in Rabies vaccine. This study aimed at comparing potency and stability of inactivated animal rabies vaccine with and without thimerosal. Therefore, two groups of rabies vaccine were produced. The results indicated that thimerosal has no deleterious effect on the vaccine; furthermore, its elimination did not influence the potency and stability of the vaccine.

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 (300μ g 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 were 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.

Thimerosal, which is approximately 50% mercury by weight is a preservative widely used in vaccines since the 1930’s. It meets the requirements for a preservative as set forth by Pharmacopeia challenge test and has been shown to be effective against a broad spectrum of pathogens. In July 1999, the Public Health Service agencies and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure but, due to the lack of appropriate alternative, it is still extensively used in multiple dose formulations of vaccines such as hepatitis-B in developing countries. In this study the effect of the removal of thimerosal in two formulations of hepatitis B vaccines containing either aluminum hydroxide or aluminum phosphate were evaluated in Balb/c mice. These formulations were administered interperitoneally and the titer of antibody was determined by ELISA technique after 28 days.The geometric mean of antibody titer (GMT), seroconversion and seroprotection rates, ED50 and relative potency of different formulations were determined. The ED50 of thimerosal-free formulations were reduced by more than 35% in both preparations. In addition, GMT ofantibody titer, seroconversion and seroprotection indicated significantly higher immunogenicity for thimerosal free formulations for both aluminum phosphate and hydroxide adjuvants.

Introduction: Existing evidence on the impact of thimerosal (THIM), acting to preserve pharmaceutical products (a preservative), on fetal neurodevelopment is very controversial. Here, we investigated the neonatal administration of THIM on behaviors including (1) locomotor activity, (2) social behaviors, and (3) stereotyped behaviors in rats. Since the development of cerebellum continues for some time after birth and it is very imperative in movement, balance, and sensory integration, the number of cerebellum Purkinje cells also were counted. Materials and Methods: The experiments were directed on 40 young male and female Wistar rats, which were randomly distributed into 4 groups including experimental (male & female) and control (male & female) groups. Each rat in the test groups were intramuscularly received 240 μ g Hg/kg THIM on postnatal days (7, 9, 11, 15), while the control contributors received saline in the same pattern. After drug interventions on the fourth postnatal week, rats were evaluated by open field test, and in eighth postnatal week, the test of three-chamber paradigm was performed on animals. At the end of the behavioral tests, histological studies were done. Results: Rats which were exposed to the THIM displayed impairments of locomotor activity and their social interactions were reduced. While the duration of freezing/grooming as stereotyped behaviors were increased significantly. The results of histological studies also showed a noteworthy decrease in the number of Purkinje cells in both sexes. Conclusions: These data prove that early postnatal exposure of children to THIM causes permanent neurobehavioral and histological impairments and if similar alterations occur in children exposed to THIM/mercurial agents, neurodevelopmental disorders may happen.

Background: Autism spectrum disorder (ASD) is identified by developmental deficits that lead to repetitive/stereotypic patterns of behavior and impaired social interactions. Studies have been indicated that exercise can decrease stereotypic behaviors in animal models of ASD. This research was designed to discover the effects of different models of forced exercise on stereotypical behaviors in a rat model of ASD induced by thimerosal (THIM). Materials and Methods: Fifty-six male Wistar rats were divided into eight groups. The rats were received saline (1 ml/kg) or THIM (300 μ, g Hg/kg) by four intramuscular injections on 7, 9, 11, and 15 postnatal days. The rats were also treated by several protocols of treadmill exercise, including non-sedentary, sedentary, protocol 1, protocol 2, and a combination of protocols 1 and 2. Results: Our study showed that THIM decreased the grooming time compared to the control group. Moreover, protocol 2 exercise significantly decreased grooming time in stranger zone 2 compared to the THIM group. Conclusions: Our results showed that stereotypical behaviors exaggerated by THIM and moderate exercise could improve ASD-associated behaviors in the THIM-treated rats. Hence, moderate exercise may be a useful protocol for the treatment of ASD.

Background and Aim: Today, Thimerosal is used as a preservative in vaccines, pharmaceutical and ‎health products. There is limited and conflicting information about the effects of this ‎substance on the structure of cortical synapses. The aim of this study was to investigate the ‎effects of Thimerosal on genes and molecules involved in the structure and function of ‎synaptic connectivity, the number of astrocytes, and neurons in the prefrontal cortex of ‎male rats. Methods: In this experimental study, 18 male rats were randomly divided into three groups: 1) experimental group receiving a dose of 3000 µg/kg Thimerosal on days 7, 9, 11, and 15 after birth, 2) solvent group receiving phosphate-buffered saline according to the same pattern, and 3) control group receiving no injection. In the fourth week after birth, samples from the prefrontal cortex were collected for immunohistochemical, histological, and molecular studies. One-way analysis of variance (ANOVA) and LSD test were used to determine statistically significant differences between the groups, and the data were expressed as Mean ± SD. Results: The results of this study revealed a significant decrease in the expression levels of Cadherin-8 (0. 18 ± 0. 079) and Synapsin-1 (0. 36 ± 0. 12) genes in the Thimerosal-exposed group compared to both control group (1 ± 0. 01 for Cadherin-8 and 1 ± 0. 009 for Synapsin-1) and solvent group (0. 91 ± 0. 097 for Cadherin-8 and 0. 84 ± 0. 10 for Synapsin-1) (p < 0. 001). Furthermore, there was a significant decrease in the number of astrocytes in the Thimerosal-exposed group (10. 66 ± 1. 86) compared to the control group (6. 43 ± 1. 01) and the solvent group (6. 93 ± 1. 39), as well as a decrease in the number of neurons (194. 66 ± 19. 59) compared to the control group (267. 99 ± 10. 19) and the solvent group (252. 33 ± 23. 06) (p < 0. 01). Conclusion: It seems that Thimerosal causes abnormal changes in the expression levels of genes ‎involved in the function and structure of synapses. Prolonged exposure to Thimerosal may lead to neurodevelopmental disorders.