Shedding light on possible contributors to autism, schizophrenia and other neuro-psychiatric disorders, Washington University researchers have found that a type of support cell in the brain, called an astrocyte, may play a role in the ability of neurons to communicate. The scientists found, in culture, that without astrocytes, communication between neurons is slowed.
THE MOST STUDIED CELLS IN THE BRAIN ARE CALLED NEURONS, BUT THEY ARENT THE MOST NUMEROUS. THERE ARE MORE SUPPORT CELLS, CALLED OLIGODENDROCYTES AND ASTROCYTES, THAN NEURONS IN THE BRAIN. AND A RESEARCH TEAM FROM WASHINGTON UNIVERSITY SCHOOL OF MEDICINE IN ST. LOUIS SAYS ITS IMPORTANT THAT SCIENTISTS FOCUS ON MORE THAN ONLY NEURONS WHEN STUDYING THE BRAIN. THEYVE FOUND THAT THE SUPPORT CELLS CALLED ASTROCYES ARE VERY IMPORTANT TO THE HEALTHY DEVELOPMENT AND FUNCTION OF NEURONS. JIM DRYDEN REPORTS
SUPPORT CELLS LIKE ASTROCYTES ARE MORE THAN JUST THE GLUE THAT HOLDS THE BRAIN TOGETHER. THOSE CELLS PERFORM IMPORTANT FUNCTIONS THAT MAKE IT POSSIBLE FOR NEURONS TO DO THEIR JOBS, ACCORDING TO NEUROSCIENCE GRADUATE STUDENT COURTNEY SOBIESKI. WORKING IN THE LABORATORY OF WASHINGTON UNIVERSITY PSYCHIATRY PROFESSOR STEVEN MENNERICK, SOBIESKI DEVELOPED A METHOD TO GROW NEURONS IN THE SAME CULTURE DISH IN WHICH SOME OF THE CELLS SAT ATOP AN ASTROCYTE AND OTHER NEURONS DIDNT. AND MENNERICK SAYS THEY FOUND THAT UNDER IDENTICAL CONDITIONS WITH THE EXCEPTION OF THE FACT THAT SOME NEURONS WERE ON ASTROCYTES AND OTHERS WERENT THE RESEARCHERS FOUND BIG DIFFERENCES IN HOW NEURONS USE THE TRANSMITTER GLUTAMATE TO SEND OUT MESSAGES.
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In the neurons lacking astrocytes, the signal was quite a bit
delayed, but several milliseconds. Now that sounds like a
small amount of time, but in the time course of electrical
communication in the nervous system, thats a lifetime. A
few milliseconds is a big deal.
MENNERICKS LAB IS HOUSED IN THE DEPARTMENT OF PSYCHIATRY AND IS AN INTEGRAL PART OF THE TAYLOR FAMILY INSTITUTE FOR INNOVATIVE PSYCHIATRIC RESEARCH, A GROUP OF INVESTIGATORS LOOKING FOR NEW TARGETS FOR TREATING PSYCHIATRIC ILLNESS. AND HE SAYS THESE FINDINGS INVOLVING ASTROCYTES MAY SUGGEST THAT THOSE CELLS ARE SOMEHOW RELATED TO PSYCHIATRIC DISORDERS.
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People have shown, for instance, that astrocyte numbers are
altered in mood disorders depression, anxiety and theres
increasing evidence for astrocyte involvement in autism and
schizophrenia. Weve also known for a long time that astrocytes
are needed for neuronal development and survival.
BUT HOW THE CELLS MAY BE AFFECTING NEURONS HASNT BEEN CLEAR PREVIOUSLY. MENNERICK SAYS THESE EXPERIMENTS SUGGEST THAT THE SLOWING DOWN OF GLUTAMATE RELEASE MAY BE PART OF THE ANSWER.
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Cells that use glutamate as a transmitter were the ones that were
affected by the loss of the astrocyte. Those are the cells that will
excite activity through the nervous system. Since its the key to
normal brain functioning and communication, we believe its also a
key to what might go wrong in many neuropsychiatric diseases.
MENNERICK AND SOBIESKI BELIEVE THAT IN BRAIN RESEARCH IT ISNT ENOUGH TO STUDY NEURONS AND IGNORE OTHER CELLS IN THE BRAIN. THEY SAY ITS VERY LIKELY THAT PROBLEMS WITH ASTROCYTES ARE INVOLVED IN CERTAIN PSYCHIATRIC DISORDERS. AND THEY SAY THE RELATIONSHIP BETWEEN ASTROCYTES AND NEURONS ALSO MAY BE INVOLVED IN OTHER BRAIN DISEASES.
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Our focus, being in a department of psychiatry, is largely on
neuropsychiatric disease. But when one thinks about some of
the disruptions that we found in this work, one also thinks
immediately of seizures, I think, of epilepsy. Epilepsy is
characterized by a temporal disruption in electrical signaling,
and so that is another disorder in which one might start to
suspect an astrocyte involvement through the mechanisms that we
pointed out in this work.
MENNERICK AND SOBIESKI REPORT THEIR FINDINGS IN THE JOURNAL OF NEUROSCIENCE. IM JIM DRYDEN