ACTIN OF SMOOTH MUSCLE CELLS AS A CRITERION OF GRAVITY-SENSITIVITY OF THE GASTROINTESTINAL TRACT OF MICE AND MONGOLIAN GERBILS; [АКТИН ГЛАДКОМЫШЕЧНЫХ КЛЕТОК КАК КРИТЕРИЙ ГРАВИЧУВСТВИТЕЛЬНОСТИ ЖЕЛУДОЧНО-КИШЕЧНОГО ТРАКТА МЫШЕЙ И МОНГОЛЬСКИХ ПЕСЧАНОК]

Despite the key role of the smooth muscle tissue (SMT) in the gastrointestinal organs functioning, mechanisms of SMT gravity sensitivity still remain inadequately studied in space biomedicine. Smooth muscle actin (a-SMA) was studied in membranes of the stomach and small gut fundus in mice C57BL/6N (experiment in 30-d BI0N-M1 mission and synchronous control BIOS-MLZh), Mongolian gerbils Meriones unguiculatus (experiment in 12-d Foton-M3 missions), and after 30-d tail-suspension according to E.R. Morey-Holton (C57BL/6N males). Immunohistochemical "detection of a-SMA was conducted in 2 \jm sections using the mouse SMA monoclonal antibodies (1:100, Zytomed Systems; Cat No. MSK030). Documentary photography and analysis of micropreparations were performed with microscope ZEISS Axio Imager A2. Quantitative analysis was performed on the basis of the area of immunopositive sections using ImageJ 1.5138. Morphometry analysis of a-SMA in muscular coat of the stomach and jejunum of the space-flown mice and gerbils detected a reduction of Immunopositive sections which points to weakening of the SMT functional activity. Gravitational sensitivity of the gastrointestinal contraction structures can be conditioned by changes in structural components of actin myofilament in smooth myocytes or myofibroblasts. Absence of changes in the o-SMA expression after tail-suspension confirms that microgravity affects functional properties of the gastrointestinal muscular coats. © 2024 Slovo Ltd. All rights reserved.