Author contribution: Rakhmetova KK — sample collection, concept and design of the study, data analysis and interpretation, writing of the manuscript; Mishina ES — histological and morphological examination, data analysis and interpretation; Vorvul AO — statistical processing of the data, writing of the manuscript; Bobyntsev II — concept and design of the study, scientific editing of the manuscript; Dolgintsev ME — data analysis and interpretation, writing of the manuscript; Bezhin AI — concept and design of the study.

Compliance with ethical standards: the study was approved by Ethics Committee of the Kursk State Medical University (Protocol № 1 of January 16, 2014). The study was carried out in compliance with the European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes and the Guidelines for conducting preclinical drug trials (Moscow, 2012).