Autism spectrum disorders (ASD) is used in medical terminology to describe developmental disorders which have characteristic symptoms: poor social interaction, communication difficulties and repetitive behaviours. Autism spectrum disorders include autism, Asperger syndrome, and pervasive developmental disorder not otherwise specified (PDD-NOS). It is estimated that the disease affects 1 per 1000 people and is four times more common among males than females. Currently, the disease is incurable and in order to mitigate its symptoms pharmacological and psychological treatment can be used.
Specific cause or causes of autism spectrum disorders are not known yet. Many risk factors that may contribute to the development of the ASD were described. The risk factors include: genetics factors, prenatal and perinatal factors, neuroanatomical abnormalities, and environmental factors.
Studies show that more than one gene may be responsible for ASD, however mutations that increase the risk of autism have not been identified yet. Some studies suggest that autism spectrum disorders may be caused by abnormal growth of neurons leading to the situation when in some parts of the brain there is too many neurons and in other areas there is too few.
The study published in “Nature” shows two ways of reversing autism-like symptoms in mice. A team of researchers led by Nahum Sonenberg of McGill University in Montreal, Quebec created a new model of autism in mice and then reversed its symptoms. The mice deprived of gene Eif4ebp2 exhibited many symptoms typical for autism.
Sonenberg and team of researchers discovered a group of proteins – neuroligins (NLGNs), which proliferate in the absence of gene Eif4ebp2. NLGNs are located in the membrane of neurons and help to create and maintain connections between nerve cells. Neuroligins connect presynaptic and postsynaptic nerve cells and mediate trans-synaptic signaling. They are essential components of the molecular machinery that enables network of neurons to process complex signals.
When Sonenberg and his co-workers were examining slices of mouse brain they found that overproduction of NLGNs in synapses which are prone to over-stimulation can cause a ‘hyperconnectivity’. This term is used in medical terminology to describe millions of neurons creating excessive connections. Many researchers believe that it can be the main reason for the symptoms of ASD.
The researchers found that the effects of deleting gene Eif4ebp2 can be reversed in mice. Sonenberg and his colleagues were testing if a small-molecule drug, which binds to one of the protein components of complex that initiates translation, can prevent creation of this complex and counteract the gene deletion. The results show that this treatment can reverse hyperconnectivity in mice. They did not show any of the symptoms typical for autism which they had exhibited previously.
The team of researchers extended their research by testing whether direct suppressing of the translation using short interfering RNAs can give the same effect. As a result of experiments, researchers found that this treatment also prevents the development of hyperconnectivity and occurrence of symptoms typical for autism.
The research give hope for effective treatment in the future but researchers still have a very long way to go.
Written by: Paulina Dzięga
Source:
1.http://pl.wikipedia.org/wiki/Autyzm_dzieci%C4%99cy
2.http://pl.wikipedia.org/wiki/Spektrum_autystyczne
3.http://en.wikipedia.org/wiki/Autism_spectrum
4.http://en.wikipedia.org/wiki/Causes_of_autism
5.http://www.nature.com/news/autism-symptoms-reversed-in-mice-1.11869
6.http://www.eneuropsychiatria.pl/Rozpowszechnienie-wystepowania-zaburzen-z-grupy-spektrum-zaburzen-autystycznych,4848-4390.html
7.http://en.wikipedia.org/wiki/Neuroligin
8.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2673233/
9.http://www.neuropsychologycentral.com/interface/content/resources/page_material/resources_general_materials_pages/resources_document_pages/autistic_behavior_etiology_and_evaluation.pdf
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