The channel protein Pannexin1 keeps nerve cells flexible and thus the brain receptive for new knowledge. Together with colleagues from Canada and the U.S., researchers at the Ruhr-Universität Bochum led by the junior professor Dr. Nora Prochnow from the Department of Molecular Brain Research describe these results in PLoS ONE.
Micrograph of the hippocampus: The blue curves show the long-term potentiation in mice with (left) and without Pannexin1 (right). Brains of animals without the channel protein respond especially sensitively to small stimuli, as the big difference between the light and dark blue curve shows. The data is based on original measurements of the study.
Image: Nora Prochnow
In the study, mice comprising no Pannexin1 in memory-related brain structures displayed symptoms similar to autism. Their nerve cells lacked synaptic plasticity, i.e. the ability to form new synaptic contacts or give up old contacts based on the level of usage.
Pannexins are abundant in the central nervous system of vertebrates
Pannexins traverse the cell membrane of vertebrate animals and form large pored channels. They are permeable for certain signalling molecules, such as the energy storage molecule ATP (adenosine triphosphate). The best known representative is Pannexin1, which occurs in abundance in the brain and spinal cord and among others in the hippocampus - a brain structure that is critical for long-term memory. Malfunctions of the pannexins play a role in the development of epilepsy and strokes.
No more scope in long-term potentiation
The research team studied mice in which the gene for Pannexin1 was lacking. Using cell recordings carried out on isolated brain sections, they analysed the long-term potentiation in the hippocampus. Long-term potentiation usually occurs when new memory content is built - the contacts between nerve cells are strengthened; they communicate more effectively with each other. In mice without Pannexin1, the long-term potentiation occurred earlier and was more prolonged than in mice with Pannexin1. “It looks at first glance like a gain in long-term memory”, says Nora Prochnow. “But precise analysis shows that there was no more scope for upward development.” Due to the lack of Pannexin1, the cell communication in general was increased to such an extent that a further increase through the learning of new knowledge was no longer possible. The synaptic plasticity was thus extremely restricted. “The plasticity is essential for learning processes in the brain”, Nora Prochnow explains. “It helps you to organise, keep or even to forget contents in a positive sense, to gain room for new inputs.”
Autistic-like behaviour without Pannexin1
The absence of Pannexin1 also had an impact on behaviour: when solving simple problems, the animals were quickly overwhelmed in terms of content. Their spatial orientation was limited, their attention impaired and an increased probability for seizure generation occurred. “The behavioural patterns are reminiscent of autism. We should therefore consider the Pannexin1 channel more closely with regard to the treatment of such diseases”, says the neurobiologist from Bochum.
Theory: feedback regulation gets out of hand without Pannexin1
According to the scientists’ theory, nerve cells lack a feedback mechanism without Pannexin1. Normally the channel protein releases ATP, which binds to specific receptors and thus reduces the release of the neurotransmitter glutamate. Without Pannexin1 more glutamate is released, which leads to increased long-term potentiation. This causes the cell to lose its dynamic equilibrium, which is needed for an efficient learning process.
N. Prochnow, A. Abdulazim, S. Kurtenbach, V. Wildförster, G. Dvoriantchikova , J. Hanske, E. Petrasch-Parwez, V.I. Shestopalov, R. Dermietzel, D. Manahan-Vaughan, G. Zoidl (2012): Pannexin1 stabilizes synaptic plasticity and is needed for learning, PLoS ONE , DOI: 10.1371/journal.pone.0051767
Prof. Dr. Nora Prochnow, Department of Molecular Brain Research, Faculty of Medicine, 44780 Bochum, Germany, Tel. +49/234/32-24406, E-Mail: Nora.Prochnow@ruhr-uni-bochum.de
Editor: Dr. Julia Weiler
Dr. Josef König | idw
HKUST researchers discover ways to regenerate corticospinal tract axons
06.07.2015 | Hong Kong University of Science and Technology
Southampton researchers go with the flow to help protect endangered European eel
06.07.2015 | University of Southampton
Wind turbines could be installed under some of the biggest bridges on the road network to produce electricity. So it is confirmed by calculations carried out by a European researchers team, that have taken a viaduct in the Canary Islands as a reference. This concept could be applied in heavily built-up territories or natural areas with new constructions limitations.
The Juncal Viaduct, in Gran Canaria, has served as a reference for Spanish and British researchers to verify that the wind blowing between the pillars on this...
New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions
A new technique pioneered at the U.S. Department of Energy's Brookhaven National Laboratory reveals atomic-scale changes during catalytic reactions in real...
Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.
Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and...
A team of scientists including PhD student Friedrich Schuler from the Laboratory of MEMS Applications at the Department of Microsystems Engineering (IMTEK) of...
The three-year clinical trial results of the retinal implant popularly known as the "bionic eye," have proven the long-term efficacy, safety and reliability of...
25.06.2015 | Event News
16.06.2015 | Event News
11.06.2015 | Event News
06.07.2015 | Power and Electrical Engineering
06.07.2015 | Press release
06.07.2015 | Physics and Astronomy