Gravity and neuronal adaptation, in vitro and in vivo—from neuronal cells up to neuromuscular responses: a first model

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.

Vestibular Responses to Gravity Alterations

“…Ion channel is the gate for the (de)polarization in a cell, and its function is generally expressed by the state probability [6].…”

“…Especially, the constructed model provides some comparable outcomes to the experimental results, and it can show an insight which has been veiled. Also, the results are directly applicable to examine the expected behavioral consequences of the astro-nauts, providing the biological changes at the molecular and cellular levels [6]. Furthermore, a model study can provide all different level of gravity including hypergravity.…”

“…The altered gravity was mainly detected in the peripheral vestibular system, especially otolith, and the corresponding neural information is sent to the central nervous system [4,5]. Initially, the changed gravity affects the membrane viscosity, which decreases or increases under hypo-or hypergravity, respectively [6]. The changes on the cell membrane modify the open state probability of ion channels, influencing the resting potential which is closely related with the neuronal action potential threshold [6].…”

“…Initially, the changed gravity affects the membrane viscosity, which decreases or increases under hypo-or hypergravity, respectively [6]. The changes on the cell membrane modify the open state probability of ion channels, influencing the resting potential which is closely related with the neuronal action potential threshold [6]. As shown in the serial reactions, all related processes are requisites for the homeostasis of body condition because all living creatures have adapted to the gravity on Earth.…”

“…As known, the most critical factor to affect the neuronal activity is the open state probability of ion channels, and it directly induces the change in the conductance between two connected neurons. For instance, the microgravity (hypo-gravity) induces the decrease of the membrane conductance, and the consequence finally reduce the transmission of the related neural information [6].…”