Plamen I Zagorchev1,
Vesela Yu Kokova2 
,
Elisaveta G Apostolova2,
Lyudmil P Peychev2
For correspondence:- Vesela Kokova Email: vesela_uk@abv.bg Tel:+35932602099
Accepted: 15 June 2018 Published: 28 July 2018
Citation: Zagorchev PI, Kokova VY, Apostolova EG, Peychev LP. Possible role of 18-kDa translocator protein (TSPO) in etifoxine-induced reduction of direct twitch responses in isolated rat nerve-skeletal muscle preparations. Trop J Pharm Res 2018; 17(7):1309-1315 doi: 10.4314/tjpr.v17i7.12
© 2018 The authors.
This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative (http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited..
Purpose: To determine the effects of etifoxine on directly-elicited twitch tension of isolated rat nerve-skeletal muscle preparations and to propose a possible explanation of the mechanism of the observed effect.
Methods: Striated muscles contractile activity was elicited by electrical field stimulation. The effects of etifoxine and nifedipine on direct single twitch response were studied.
Results: The results demonstrate that the effect of etifoxine on skeletal muscle depends on the concentrations: low concentrations (10-8 i2; and 10-7 i2;) have little effect on twitch tension, whereas higher concentrations (10-6 i2; and 10-5 i2;) induced a significant decrease in the direct single twitch response in comparison to controls. The mean IC50 (reduction of directly-elicited twitch tension) of etifoxine was 0.85 x 10-6 M. The selective L-type calcium channel blocker nifedipine (10-5 i2;) induced a greater decrease in the muscle force than 10-6 i2; etifoxine. The different abilities of etifoxine and nifedipine to reduce direct single twitch response may be related to their distinct mechanisms of action. The observed effect of etifoxine could be more complex. Probably etifoxine acts as a non-selective agent not only on L-type calcium channels Cav1.1 localized in sarcolemma but also on 18-kDa translocator protein (TSPO) in skeletal muscle.
Conclusion: Etifoxine-induced reduction of direct twitch responses could be attributed to an effect on TSPO and Cav1.1. Knowledge of the effects of TSPO ligands on the contraction of skeletal muscle might explain the role of TSPO in muscle contractility.
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