low prenatal vit. D & schizophrenia risk

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Just saw this and thought people on the list might be interested:

Vitamin-deficient rats show symptoms of schizophrenia

2 February 2002 1:00 GMT

by Spinney, BioMedNet News

Australian researchers have produced the first compelling evidence that low

prenatal vitamin D might be a risk factor for schizophrenia. They have shown

that the brains of vitamin D-depleted neonate rats have proportionally thinner

cortices and larger ventricles than undepleted controls - changes that are also

seen in the brains of schizophrenics.

The group, led by McGrath of the Queensland Centre for Schizophrenia

Research in Wacol, revealed its new work, which is unpublished, on Saturday at

the International Society for Developmental Neuroscience (ISDN 2002) meeting in

Sydney.

The work shows that mitosis is elevated in the dentate gyrus, basal ganglia and

hypothalamus of the vitamin D-deficient rats. In a separate study, McGrath's

group has recently verified that levels of cell mitosis in schizophrenic brains

are also raised.

In behavioral studies, the rats showed a reduced pre-pulse inhibition (PPI) to

acoustic startle - the degree to which a low pulse of sound preceding a loud

test pulse inhibits their startle reaction to that test pulse. Reduced PPI is

regarded as the gold standard test of animal models of schizophrenia.

And the first clues to the mechanisms by which vitamin D might be influencing

brain development have become evident, according to the team's developmental

neurobiologist Alan Mackay-Sim of the Centre for Molecular Neurobiology at

Griffith University in , Queensland.

" We get big changes in nerve growth factor levels and receptors, " Mackay-Sim

told BioMedNet News.

Gene array analyses found that vitamin D depletion altered the expression of a

vast number of genes - the majority being downregulated. Among them are genes

regulating neurotransmission, cell cycle control, cell trafficking and the

cytoskeleton.

Many of the genes matched those found to be altered in similar gene array

studies of post-mortem tissue from schizophrenic brains.

Vitamin D synthesis in the body is triggered by UVB light. But until a few years

ago it was thought to play no role in the brain. When McGrath put forward his

controversial theory, in 1999, he argued that it could help to explain why the

incidence of schizophrenia was higher among those born in the winter and spring,

and among dark-skinned immigrants to northern countries.

What the new research shows, says Mackay-Sim, is that vitamin D has a broader

significance for brain development: " It's having profound effects on the brain

which could lead to more than just schizophrenia, because schizophrenia is only

operating in [genetically] susceptible individuals. "

And depletion until birth, later corrected, can have long-reaching effects into

adulthood, he adds.

Rees of the Department of Anatomy and Cell Biology at the University of

Melbourne, who studies schizophrenia and early brain development, says she looks

forward to seeing confirmation of the findings.

Rees' own group has shown that a number of insults occurring during development

can lead to enlarged ventricles in the brains of adolescent guinea pigs,

including hypoxia and malnutrition.

So Vitamin D depletion may not turn out to be the only culprit.

However, says McGrath, when you take into account that large-scale studies in

the US have suggested up to 12% of women of childbearing age are vitamin

D-deficient, the implications of his research are enormous. " If they were

children, they would have rickets, " he noted.

The incidence of schizophrenia in the population is about 1 in 100.