Impact of a simulated gravity load for atmospheric reentry, 10 g for 2 min, on conscious mice

Abstract

The Japan Aerospace Exploration Agency recently performed a mouse experiment in the International Space Station in which mice were raised for 35 days, retrieved using the Dragon spacecraft, and then harvested for analysis 2 days after splashdown. However, the impact of the retrieval procedure, which exposed mice to 5-10 g for 2 min during atmospheric reentry and splashdown, was unknown. Therefore, the purpose of this study was to examine the impact of a 10 g load for 2 min (using a gondola-type centrifuge with a 1.5-m arm installed at Gifu University) on conscious mice. Plasma corticosterone increased at 30 min after load application and recovered at 90 min. Significant Fos expression was observed in the vestibular nuclei (VeN), paraventricular hypothalamic nucleus (PVN), and central nucleus of the amygdala (CeA). Rearing behavior and food intake were suppressed. Mice with vestibular lesions demonstrated increased corticosterone and Fos expression in the PVN, but neither suppression of food intake and rearing behavior nor increased Fos expression in the VeN and CeA. These results suggest that the simulated gravity load induced a transient stress response, hypoactivity, and a vestibular-mediated suppression of food intake.

Development of new experimental platform ‘MARS’—Multiple Artificial-gravity Research System—to elucidate the impacts of micro/partial gravity on mice

“…Prior to the space experiment, we conducted various ground-based biocompatibility tests of the new hardware, as well as the Coriolis Effect, during short radius-centrifugation onboard and steady state acceleration during the launch and return phases 15 – 17 . The success of these ground-based biocompatibility tests convinced us to conduct space experiments with our new hardware.…”

Hypergravity Increases Blood–Brain Barrier Permeability to Fluorescent Dextran and Antisense Oligonucleotide in Mice

“…Hypergravity exposure at 2 g increases the corticosterone concentration when it is measured during the first hour of exposure [63]. The increase in the hypergravity level can transiently increase the plasma corticosterone level [64]. Nevertheless, as our data showed, after 24 h of weak exposure at 2 g, the corticosterone levels were not altered in the first hour following the stop of the centrifuge [65].…”

Stroboscopic lighting with intensity synchronized to rotation velocity alleviates motion sickness gastrointestinal symptoms and motor disorders in rats

“…Furthermore, numerous studies have reported that activation of vestibular-autonomic related brain areas was critical for the production of autonomic MS manifestations (Yates et al, 1999 ; Pompeiano et al, 2004 ; Balaban et al, 2014 ; Nalivaiko et al, 2014 ). Provocative motion stimulation could increase the expression of Fos protein (a marker of neuronal activity) in vestibulo-autonomic nuclei such as the caudal vestibular nucleus (CVN) including caudal medial and spinal vestibular nucleus, the nucleus of solitary tract (NTS), the parabrachial nucleus (PBN), the central nucleus of amygdala (CeA), and in stress-related areas such as the locus coeruleus (LC) and the paraventricular nucleus of hypothalamus (PVN) (Nakagawa et al, 2003 ; Cai et al, 2010 ; Balaban et al, 2014 ; Morita et al, 2017 ). These structures constitute neural networks that were believed to contribute to MS induced by vestibular stimulation (Balaban et al, 2014 ; Zhou et al, 2017 ).…”

“…Conditioned gaping response that can be elicited during exposure to a context previously paired with nauseant agents or provocative motion can be alleviated by corresponding anti-emetic and anti-MS drugs, making it plausible to serve as a rat model of conditioned nausea (Limebeer et al, 2008;Parker, 2014;Zhou et al, 2017;Qi et al, 2019;Rock et al, 2022). In addition, defecation response and decreased spontaneous locomotion activity were also observed in rats and mice exposed to whole-body rotation (Ossenkopp and Frisken, 1982;Ossenkopp et al, 1994;Yu et al, 2007;Limebeer et al, 2008;Morita et al, 2017;Wang et al, 2017;Deshetty et al, 2021). Balance disorder characterized by the decline in the time taken traversing balance beam was also elicited by passive motion stimulation in both rats and mice (Tung et al, 2014;Zhou et al, 2017;Manno et al, 2020;Zhong et al, 2022).…”