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Could a treatment for Parkinson's disease help the social impairment of diseases like autism?

Monday September 02, 2013

Medical Xpress - A stressful pregnancy might be the last thing a future mother needs, but it is to her unborn baby that this stress spells real trouble. All because stress hormones (called glucocorticoids or GCs) can change foetal brain development, causing the new individuals to develop serious behavioural and/or emotional problems. Despite this danger we remain far from understanding how GCs work. But now a study in rats by a Portuguese team has discovered that the prenatal (before birth) effect of GCs on behaviour is linked to problems in dopamine (a brain messenger). Surprisingly, they also found that it is possible (and easy) to reverse the abnormal behaviours seen in these individuals, a discovery with possible implications for neurological diseases like autism and attention-deficit hyperactivity disorder (ADHD).

Sonia Borges and Barbara Coimbra from the University of Minho found that when rats are exposed to high levels of GCs during its foetal formation, not only they develop abnormal behaviour, but their dopamine levels are lower than normal in several brain areas linked to pleasure. Once normal levels are restored, though, the emotional and social abnormalities seen in these animals disappear. This seems to show that brain changes triggered by early life trauma could be reversed by dopamine, what is remarkable. The study, which is coming out September in the journal Neuropsychopharmacology, has implications for neuropsychiatric disorders associated with dopamine and early neurodevelopmental problems, such as depression, anxiety, ADHD, schizophrenia and autism. Ana João Rodrigues, one of study leaders (together with Nuno Sousa) warns for the need to be very cautious though " Although there are some clues that prenatal stress may affect emotional and social behaviour in humans, our work is still at very early stages. All we can really say" – she points – "is that dopamine is able to improve deficiencies in social behaviour and this might have important implications for diseases characterised by social impairment".

GCs are crucial life hormones – if they mediate the negative effects of stress, they are also involved in all types of normal functions of the body; from controlling the immune system and regulate the metabolism to even help the maturation of foetal organs, GCs are indispensable for life. In fact, even if they can provoke problems in the foetal brain, these hormones are still routinely given to pregnant women in danger of premature delivery, to help foetal lung maturation. So it is urgent to understand better how GCs work to be able to make better crucial, even life-depending, decisions.

So in the study to be published Borges, Coimbra and colleagues looked at their effects before birth, by exposing rats still in the uterus to high levels of GCs (the equivalent of having a very stressed mother), and found that they went to develop signs of depression and lack of motivation (like reported before), but they also saw social impairments. Animals exposed to prenatal stress played less, had less "happy" calls ("happy" and "sad" calls can be differentiated by their sound frequencies) but also interacted awkwardly with others.

(2 Sep 2013). Medical Xpress. Could a treatment for Parkinson's disease help the social impairment of diseases like autism? medicalxpress.com