Protective and restorative potency of Vitamin D on persistent biochemical autistic features induced in propionic acid-intoxicated rat pups

Reducing exposure to toxic environmental agents is a critical area of intervention. Prenatal or postnatal exposure to certain chemicals has been documented to increase the risk of autism spectrum disorder. Propionic acid (PA) found in some foods and formed as a metabolic product of gut microbiota has been reported to mediate the effects of autism. Results from animal studies may help to identify environmental contaminants and drugs that produce or prevent neurotoxicity, and may thereby aid in the treatment of neurodevelopmental disorders such as autism. The present study investigated the protective and/or therapeutic effects of vitamin D against brain intoxication induced by propionic acid (PPA) in rats.

Twenty-eight young male Western Albino rats were enrolled in the present study. They were grouped into four equal groups of 7. The control group received only phosphate buffered saline; the oral buffered PPA-treated group received a neurotoxic dose of 250 mg/kg body weight/day for 3 days; and the Vitamin D-protected group received 1000 IU/kg/day of alpha, 25-dihydroxyvitamin D (3) (1, 25-VD) for two weeks, after which the rats were injected with PPA 250 mg/Kg body weight/day for 3 days. The fourth group received PPA 250 mg/Kg body weight/day for 3 days followed by alpha, 25-dihydroxyvitamin D (3) (1, 25-VD) for two weeks (Vitamin D therapeutic effect). Vitamin D and calcium were measured in the plasma of the four studied groups. Serotonin, interferon gamma (IFN-γ), glutathione-s-transferase activity and DNA double helix breaks were assayed in the brain tissue of the rats for all groups.

The obtained data showed that the PPA-treated group demonstrated higher plasma vitamin D levels compared to the control rats, together with multiple signs of brain toxicity, as indicated by a depletion of serotonin (5HT), an increase in IFN-γ and inhibition of glutathione-s-transferase activity as three biomarkers of brain dysfunction. Additionally, Comet DNA assays showed remarkably higher tail length, tail DNA % damage and tail moment as a neurotoxic effect of PPA.

Vitamin D showed a greater protective than therapeutic effect on PPA-induced neurotoxicity in rats, as there was a remarkable amelioration of the impaired biochemically measured parameters representing neurochemical, inflammation, and detoxification processes.