INFLUENCE OF MODELING OF GRAVITATIONAL UNLOADING ON THE POSTSYNAPTIC
ACETYLCHOLINE RECEPTOR ORGANIZATION AND ACETYLCHOLINESTERASE ACTIVITY
IN NEUROMUSCULAR SYNAPSES OF RAT FAST AND SLOW MUSCLES
O.V. Tyapkina,1,2 L.F. Nurullin,1,2 K.A. Petrov,1,3 E.M. Volkov 2,*
1 Kazan Institute of Biochemistry and Biophysics KSC RAS,
2 Kazan State Medical University and
3 A.E. Arbuzov Institute of Organic and Physical Chemistry KSC RAS, Kazan;
* e-mail: euroworm@mail.ru
Using immunofluorescent techniques, we have revealed that, after 35 days of rats hindlimb unloading, neuromuscular
synapses of fast and slow muscles show enhanced fluorescence intensity and decreased area of fluorescent
staining of acetylcholine receptors; increased fluorescent intensity and area of fluorescent staining for
acetylcholinesterase. The ratio of the number of postsynaptic acetylcholine receptors and the amount of acetylcholinesterase
changed as well as their spatial position in relation to each other. These rearrangements correspond
to electrophysiological data on the reduction of the amplitude of the miniature endplate currents in both
muscles. Identified synapses restructuring accompanied by a decrease in the volume of muscle fibers. Hindlimb
unloading (simulation of hypogravity) leads to an increase in functional activity of acetylcholinesterase on the
background of reduced postsynaptic membrane area occupied by acetylcholine receptors. This leads to a decrease
in the amplitude of excitatory postsynaptic potentials thereby reducing the nerve-muscle excitation transmission
safety factor.
Key words: hypogravity modeling, fast and slow muscles, acetylcholinesterase, acetylcholine receptors
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