Study of mouse behavioural response in microgravity: ethogram and neurobiological related

The conquest of space, which started with the dog Laika in 1966 to be followed few years later by Yuri Gagarin, has witnessed an increasing numbers of both vertebrates (tadpoles, frogs, rats mice etc.) and invertebrates (flies, scorpions, protozoa) species exposed to zero gravity levels. Animals are sent into orbit to proactively foresee possible health problems in humans. The issue of animal exposure to un-physiological gravity is of primary importance to i) understand behavioural and physiological adaptations in such environment as well as ii) develop coun-termeasures to improve 0-g life conditions and reduce possible animal suffering. The Mouse Drawer System (MDS), an Italian facility, has been transferred to the International Space Sta-tion with a first experiment investigating mechanisms underlying bone mass loss in microgravity in mice. Preliminary and ground-based control experiments have been conducted with six mice housed individually inside the MDS facility for 20 and 100 days. The behavioural repertoire of wild-type and transgenic mice housed in the MDS has been videorecorded with the observation subsystem, which allows to monitor animal's behavior through the use of 6 video cameras. The behavioural patterns characterizing mice in the MDS system have been finely analysed at several time points during the the experiment. Moreover, neurobiological parameters, known to be involved in the response to stress, have been evaluated. In particular, NGF and BDNF levels have been measured in the central nervous system (hippocampus, striatum, and cortex), adrenal gland and limbs. Preliminary data from ground based experiment revealed Several dif-ferences in behavioural profile between wt and tg mice, with transgenic ones apparently more active than wild type controls. Moreover a clear difference in time spent in different areas of the MDS cage was observed. Finally changes in neurotrophins levels were observed in relation to both genotype and environmental conditions. Data so far collected will be used as baseline and will compared with those obtained during spaceflight exposure currently under analysis and a fine characterization of the behavioral repertoire (ethogram) of the mice exposed to space environment will be reported.