Gravity and neuronal adaptation [01.09.17]
Using in vivo und in vitro data, Dr. Florian P.M. Kohn from the Department of Membrane Physiology together with a colleague from the Institute of Sport and Sport Science of the University of Freiburg postulates a model, how neuronal cells adapt to gravitational changes.
Photo Credit: Wikimedia
Original Studies:
Kohn, F., Hauslage, J. & Hanke, W. Microgravity Sci. Technol. (2017) Membrane Fluidity Changes, A Basic Mechanism of Interaction of Gravity with Cells? doi.org/10.1007/s12217-017-9552-y (2017)
Abstract: All life on earth has been established under conditions of stable gravity of 1g. Nevertheless, in numerous experiments the direct gravity dependence of biological processes has been shown on all levels of organization, from single molecules to humans. According to the underlying mechanisms a variety of questions, especially about gravity sensation of single cells without specialized organelles or structures for gravity sensing is being still open. Biological cell membranes are complex structures containing mainly lipids and proteins. Functional aspects of such membranes are usually attributed to membrane integral proteins. This is also correct for the gravity dependence of cells and organisms which is well accepted since long for a wide range of biological systems. However, it is as well established that parameters of the lipid matrix are directly modifying the function of proteins. Thus, the question must be asked, whether, and how far plain lipid membranes are affected by gravity directly. In principle it can be said that up to recently no real basic mechanism for gravity perception in single cells has been presented or verified. However, it now has been shown that as a basic membrane parameter, membrane fluidity, is significantly dependent on gravity. This finding might deliver a real basic mechanism for gravity perception of living organisms on all scales. In this review we summarize older and more recent results to demonstrate that the finding of membrane fluidity being gravity dependent is consistent with a variety of published laboratory experiments. We additionally point out to the consequences of these recent results for research in the field life science under space condition.
Kohn FPM, Ritzmann R. (2017) Gravity and neuronal adaptation, in vitro and in vivo-from neuronal cells up to neuromuscular responses: a first model. Eur Biophys J. 2017 Jun 27. doi: 10.1007/s00249-017-1233-7. [Epub ahead of print]
Abstract: For decades it has been shown that acute changes in gravity have an effect on neuronal systems of human and animals on different levels, from the molecular level to the whole nervous system. The functional properties and gravity-dependent adaptations of these system levels have been investigated with no or barely any interconnection. This review summarizes the gravity-dependent adaptation processes in human and animal organisms from the in vitro cellular level with its biophysical properties to the in vivo motor responses and underlying sensorimotor functions of human subjects. Subsequently, a first model for short-term adaptation of neuronal transmission is presented and discussed for the first time, which integrates the responses of the different levels of organization to changes in gravity.
