Oxidative stress and space biology: An organ-based approach

Abstract

The environment of space provides many challenges to the human physiology and therefore to extended habitation and exploration. Research to define and countermeasures to address these challenges have been explored for well over 40 years yet success in alleviating these challenges has been inadequate, due in part to the lack of investigative tools (subject number and technology) to monitor and diagnose conditions in real time and by the overall lack of a relevant data base to understand the central causative agent(s) responsible for physiological adaptation and homeostasis in space [1-5]. Space flight adaptation syndromes are a product of the environmental conditions and the synergistic reaction of the systemic human physiology, which together combine to produce a combinatorial syndrome that must be resolved in order to safely inhabit and explore space, especially for extended periods [3-6]. This paper documents an exciting glimpse of current pertinent scientific literature sustaining the involvement of oxidative stress and damage (OSaD) [7,8] as a significant contributing factor in the following areas of Earth-based and space flight-related dysregulation of: (1) bone loss [9-13]; (2) cardiovascular function [14]; (3) immune insufficiency and metabolism [15-17]; (4) neurological impairment [18]; and (5) potential countermeasure implementation [18,19]. The cited literature illuminates the environmental challenges of spaceflight encompassing reduced gravity, radiation, varying atmospheric conditions, such as hyperoxia and hypoxia experienced during extravehicular and intravehicular activity (EVA/IVA), and evidence of synergistic effects that portend substantial consequences for long duration/exploration class missions. Now with 21st century scientific tools and advances in genomics, proteomics, and metabolomics ("omics") we have the resources to define syndromes at the molecular and systemic levels by enlisting a holistic approach to the assessment of the space flight physiology and to countermeasure development. To accomplish this, one must seek a "common denominator" that has systemic effects on the function of the entire physiology and stems from both environmental conditions (reduced gravity, radiation, mental and physical stress, etc.) and the byproducts of the human systems biology (reduction oxidation (REDOX)) equilibrium, free radical balance, and reactive oxygen and nitrogen species (ROS and RNS). One such common denominator is the stabilization of physiological homeostasis and control of OSaD in the body [7,8,20].