Dietary intervention of mice using an improved Multiple Artificial-gravity Research System (MARS) under artificial 1 g

Abstract

Japan Aerospace Exploration Agency (JAXA) has developed mouse habitat cage units equipped with an artificial gravity-producing centrifuge, called the Multiple Artificial-gravity Research System (MARS), that enables single housing of a mouse under artificial gravity (AG) in orbit. This is a report on a hardware evaluation. The MARS underwent improvement in water leakage under microgravity (MG), and was used in the second JAXA mouse mission to evaluate the effect of AG and diet on mouse biological system simultaneously. Twelve mice were divided into four groups of three, with each group fed a diet either with or without fructo-oligosaccharide and housed singly either at 1 g AG or MG for 30 days on the International Space Station, then safely returned to the Earth. Body weight tended to increase in AG mice and decrease in MG mice after spaceflight, but these differences were not significant. This indicates that the improved MARS may be useful in evaluating AG and dietary intervention for space flown mice.

Nrf2 contributes to the weight gain of mice during space travel

“…After arrival at the ISS, mice were relocated to the HCU by the crew. We used an HCU that accommodates one mouse per cage 11,12 . Before mice were returned to Earth, they were transferred back into the TCU and loaded into the Dragon capsule which subsequently splashed down in the Pacific Ocean offshore from Southern California on May 5.…”

“…The HCU rev.1 is an onboard habitation cage that accommodates one mouse per cage 11 , 12 . The HCU is equipped with a food bar, watering system (two redundant water nozzles and a water balloon acting as power-free pressure source), an odor filter, two fans (for redundancy) for air ventilation, waste collecting equipment, an LED/IR video camera with a wiper inside the cage to keep the observation window clean.…”

“…These apparatuses in combination can house mice individually and realize artificial gravity experiments in space. In the first and second missions utilizing this equipment, referred to as Mouse Habitat Unit-1 and -2 (MHU-1 and MHU-2 conducted in 2016 and 2017, respectively), 12 wild-type (WT) male mice were successfully launched each time, and all the mice returned safely to Earth after approximately 1 month stays in the ISS 11,12 . One salient finding in these missions is that ageing phenotypes, such as reduction of bone density and muscle mass, were markedly accelerated during space flight; notably, these phenotypes could be prevented by housing in space with artificial gravity.…”

Gut Microbiome and Space Travelers’ Health: State of the Art and Possible Pro/Prebiotic Strategies for Long-Term Space Missions

“…Additional mechanistic studies under microgravity and simulated space environment, but also intervention studies and clinical trials directly in space travelers are needed to support current evidence on pre-, probiotics or combined strategies on Earth, before these microbiota manipulation tools can be integrated into spaceflight clinical practice. The use of prebiotics for the production of SCFAs is currently being investigated for space travel (Matsuda et al, 2019;Akiyama et al, 2020).…”

Integrated RNA-seq Analysis Indicates Asynchrony in Clock Genes between Tissues under Spaceflight

“…Rodent models are often used as analogs for estimating biological mechanisms inside human tissues [ 3 , 4 ]. Mice studies under spaceflight conditions have been successfully conducted to elicit molecular mechanisms at the tissue and cellular levels [ 3 , 5 , 6 , 7 , 8 ].…”