Müller cell gliotic response in the retina of the newts exposed to real and simulated microgravity
Abstract
The effects of real and simulated microgravity on the eye tissue regeneration of newts (Pl. waltli) after lens and/or retina removal were investigated. Changes in Müller glial cells in the retina of eyes regenerating after lens extirpation were detected in newts exposed to clinostat-ing. The cells were hypertrophied, and their processes thickened. Such changes were viewed as specific of reactive gliosis [1]. Later experiments onboard the Russian biosatellite Bion-11 showed similar changes in the retinas of newts regenerating after a two-week spaceflight. In the Bion-11 animals, GFAP, the major structural protein of macroglial cells was found to be up-regulated [2]. In more recent experiments onboard Foton-2 (2005) and Foton-M3 (2007), GFAP expression in retinas of space-flown, ground control (kept at 1 g), and basal control (sacrificed on launch day) newts was quantified, using microscopy, immunohistochemistry, and digital image analysis. It was found that Müller cell processes of non-operated animals dis-u played low GFAP immunolabeling. A low level of immunoreactivity was also observed in basal controls. In contrast, retinas of space-flown animals showed greater GFAP immunoreactivity associated with both an increased cell number and a higher density of intermediate filaments [3]. This, in turn, was accompanied by up-regulation of stress protein (HSP90) and growth factor (FGF2) expressions. It can be postulated that such a response of Müller cells was to mitigate the retinal stress in newts exposed to microgravity. Although the exact mechanisms remain unknown, it can be hypothesized that GFAP up-regulation is mediated by HSPs and growth factors, particularly by FGF2. Taken together, these data suggest that the retinal population of macroglial cells is sensitive to gravity changes and that in space it can react by enhancing its neuroprotective function. [1] Grigoryan E.N., Anton H.J., Mitashov V.I. Adv. Space Res. 1998. V. 22. N.2. P. 293-301. [2] Grigoryan E.N., Tuchkova S.Ya., Poplinskaya V.A., Mitashov V.I. Aviakosm. Ekol. Med. 1999. V. 33. N.3. P. 15-20 (In Russian). [3] Grigoryan E.N., Poplinskaya V.A., Domaratskaya E.I., Novikova Y.P., K.S. Aleinikova K.S., Dvorochkin N., Almeida E.A.C. Tissue Regeneration in Urodela on Foton-M3. J. Gravit. Physiol. 2008. V. 15. N.1. P. 277-280.
- Publication:
-
38th COSPAR Scientific Assembly
- Pub Date:
- 2010
- Bibcode:
- 2010cosp...38.3417G