The Developmental vitamin D model (DVD) as an animal model for schizophrenia (2007–2009)
Most Australians have the opportunity to enjoy the natural benefits of sunlight, however many Australians lack vitamin D. We have shown that even in Queensland, the so-called Sunshine State, vitamin D levels in the middle of winter are below World Health Organisation recommended levels. We are exploring low maternal vitamin D as a biological explanation for the universal phenomena worldwide of a 7-10% increase in the incidence of patients born with schizophrenia in the colder months of the year. Schizophrenia is a developmental disease that presents in adolescence and affects about 1% of the world's population. To date we have shown increased amounts of schizophrenia in offspring from mothers that had low blood vitamin D levels during pregnancy or who had inadequate vitamin D intake. Early signs therefore appear promising but obviously more research is required to confirm this idea. Our studies in animals have revealed that by restricting vitamin D intake in pregnant rats, newborns have brains that develop differently. Most notably lateral ventricle volume is increased, a key anatomical finding in patients with schizophrenia. When these animals become adults the increase in lateral ventricles persists. Also when we explore the behaviour of these animals we find a deficit in learning and memory similar to that seen in many schizophrenic patients. Furthermore when we expose these animals to agents that induce psychosis or agents that block psychosis in patients we see a heightened sensitivity in animals that were deprived of this vitamin in utero particularly in locomotion. These behavioural findings are consistent with the best animal models for schizophrenia. At a mechanistic level they indicate an abnormality in the two major neurotransmitters in the brain that have been consistently linked with this disease, dopamine and glutamate. The experiments outlined in this application will attempt to establish the neurochemical basis for these altered behaviours.