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Purpose: To study the effect of simvastatin on behavioral performance in a rat model of autism, and its effect on hippocampal brain-derived BDNF-TrkB pathway.
Methods: Twelve rats with valproic acid (VPA)-induced autism were randomly divided into model group and simvastatin group, while six healthy rats served as normal control group. Rats in the simvastatin group received the drug (5 mg/kg) via i.p. route, while rats in model group and normal control group were injected with equivalent volume of normal saline in place of simvastatin. Capacity for interaction and repetitive stereotyped behavior, as well as results of Morris water maze test were determined for each group. The expressions of BDNF-TrkB proteins were assayed with immunoblotting.
Results: The frequencies of sniffing normal saline, alcohol and rat urine were significantly higher in model and simvastatin rats than in normal rats, but they were significantly lower in simvastatin-treated rats than in model rats (p < 0.05). There was higher duration of turning, jumping and grooming in the model group and simvastatin group than in the normal rats, but the duration was significantly reduced in simvastatin rats, relative to model rats. Escape latency times was significantly longer in model and simvastatin rats than in controls, but number of target quadrant crossings was significantly reduced. However, escape latency time was lower in simvastatin rats than in model rats, but number of target quadrant crossings was significantly higher. The model and simvastatin rats had down-regulated levels of BDNF and TrkB protein, relative to control rats, but there were markedly higher levels of these proteins in simvastatin-treated rats than in model rats.
Conclusion: Simvastatin improves the behavioral performance of autistic rats by regulating BDNF/TrkB signal axis. This finding may be useful in the development of new drugs for treating autism.