Exposure to microgravity leads to modifications of several physiological processes whose mechanisms are not clearly understood. This study aimed to determine whether modeled microgravity conditions performed with a three dimensional clinostat (Random Positioning Machine, RPM) influence intestinal transit in the rat and the expression of enzymes involved in this process and gastrointestinal homeostasis: the inducibile isoform of nitric oxide synthase (iNOS), ciclooxygenase (COX-1, 2), ICAM-1 and heat shock proteins (HSP 70 and 90). Rats, individually housed, were studied in 3 groups: RPM, kept in a semicylinder fixed on the RPM and two control groups: one kept immobilized in a semicylinder on the floor of RPM (CG), to rule out a possible effect of immobilization stress and another with animals kept in a stan- dard cage (CC). The present study shows that RPM reduced rat intestinal transit and that this effect could be medi- ated by an increase of iNOS, ICAM 1 and Hsp 70 expression as well as by a reduction of COX-2 expression. While we could not rule out a role of immobilization stress, data on intestinal iNOS and HSP 70 as well as HSP 90 in stom- ach support the idea that RPM reduced intestinal transit in the rat, a process with an important role in some adap- tive mechanisms.
EFFECTS OF MODELED MICROGRAVITY CONDITIONS ON RAT INTESTINAL TRANSIT / Marzocco, S; Autore, G; Forte, G; Muggironi, G.; Bianco, G; Pippia, P; Pinto, A; Peana, Alessandra Tiziana. - In: JOURNAL OF GRAVITATIONAL PHYSIOLOGY. - ISSN 1077-9248. - 16:2(2009), pp. 9-16.