Genome and Hormones: Gender Differences in Physiology Invited Review: Gender issues related to spaceflight: a NASA perspective (original) (raw)
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Frontiers in Physiology, 2018
Space flight-induced physiological deconditioning resulting from decreased gravitational input, decreased plasma volume, and disruption of regulatory mechanisms is a significant problem in returning astronauts as well as in normal aging. Here we review effects of a promising countermeasure on cardiovascular systems of healthy men and women undergoing Earth-based models of space-flight. This countermeasure is produced by a centrifuge and called artificial gravity (AG). Numerous studies have determined that AG improves orthostatic tolerance (as assessed by various protocols) of healthy ambulatory men, of men deconditioned by bed rest or by immersion (both wet and dry) and, in one case, following spaceflight. Although a few studies of healthy, ambulatory women and one study of women deconditioned by furosemide, have reported improvement of orthostatic tolerance following exposure to AG, studies of bed-rested women exposed to AG have not been conducted. However, in ambulatory, normovolemic subjects, AG training was more effective in men than women and more effective in subjects who exercised during AG than in those who passively rode the centrifuge. Acute exposure to an AG protocol, individualized to provide a common stimulus to each person, also improved orthostatic tolerance of normovolemic men and women and of furosemide-deconditioned men and women. Again, men's tolerance was more improved than women's. In both men and women, exposure to AG increased stroke volume, so greater improvement in men vs. women was due in part to their different vascular responses to AG. Following AG exposure, resting blood pressure (via decreased vascular resistance) decreased in men but not women, indicating an increase in men's vascular reserve. Finally, in addition to counteracting space flight deconditioning, improved orthostatic tolerance through AG-induced improvement of stroke volume could benefit aging men and women on Earth.
Journal of Investigative Medicine, 2006
Background: Exposure to microgravity induces cardiovascular deconditioning, manifested by orthostatic intolerance (OI). We assessed the renal, cardioendocrine, and cardiovascular responses of women and men to simulated microgravity to examine the impact of gender on OI. Methods: Fifteen healthy female and 14 healthy male subjects were given a constant diet for 3 to 5 days, after which they underwent a tilt-stand test (pre-TST) and began 14 to 16 days of head-down tilt bed rest (HDTB), followed by a repeat tilt-stand test (post-TST). Female subjects began HDTB so that the post-TST was at the same time in their menstrual cycle as their pre-TST. Twenty-four-hour urine collections (daily), hormonal measurements, plethysmography, and cardiovascular system identification were performed. Results: The times to presyncope were significantly different for men and women before (p = .005) and after HDTB (p = .001), with all of the women but only 50% of the men experiencing presyncope during the pre-TST (p = .002) and all of the women but only 64% of the men experiencing presyncope during the post-TST. At baseline, the following differences between women and men were observed: women had higher serum aldosterone levels (p = .02), higher parasympathetic responsiveness (p = .01), lower sympathetic responsiveness (p = .05), and lower venous compliance (p = .05). Several parameters changed with HDTB in both men and women. In a double-blinded randomized trial, midodrine (5 mg orally) or placebo given to female subjects 1 hour before post-TST was ineffective in preventing OI. Conclusion: In conclusion, the frequency of OI is higher in women than in men and is not modified by midodrine at the dose used. This increased susceptibility is likely secondary to intrinsic basal differences in the activity of volume-mediated parasympathetic and adrenergic systems and in venous tone. Thus, approaches to reduce OI in women are likely to differ from those effective in men.
Genome and Hormones: Gender Differences in Physiology
This minireview provides an overview of known and potential gender differences in physiological responses to spaceflight. The paper covers cardiovascular and exercise physiology, barophysiology and decompression sickness, renal stone risk, immunology, neurovestibular and sensorimotor function, nutrition, pharmacotherapeutics, and reproduction. Potential health and functional impacts associated with the various physiological changes during spaceflight are discussed, and areas needing additional research are highlighted. Historically, studies of physiological responses to microgravity have not been aimed at examining gender-specific differences in the astronaut population. Insufficient data exist in most of the discipline areas at this time to draw valid conclusions about genderspecific differences in astronauts, in part due to the small ratio of women to men. The only astronaut health issue for which a large enough data set exists to allow valid conclusions to be drawn about gender differences is orthostatic intolerance following shuttle missions, in which women have a significantly higher incidence of presyncope during stand tests than do men. The most common observation across disciplines is that individual differences in physiological responses within genders are usually as large as, or larger than, differences between genders. Individual characteristics usually outweigh gender differences per se.
Journal of Applied Physiology, 2001
This minireview provides an overview of known and potential gender differences in physiological responses to spaceflight. The paper covers cardiovascular and exercise physiology, barophysiology and decompression sickness, renal stone risk, immunology, neurovestibular and sensorimotor function, nutrition, pharmacotherapeutics, and reproduction. Potential health and functional impacts associated with the various physiological changes during spaceflight are discussed, and areas needing additional research are highlighted. Historically, studies of physiological responses to microgravity have not been aimed at examining gender-specific differences in the astronaut population. Insufficient data exist in most of the discipline areas at this time to draw valid conclusions about genderspecific differences in astronauts, in part due to the small ratio of women to men. The only astronaut health issue for which a large enough data set exists to allow valid conclusions to be drawn about gender differences is orthostatic intolerance following shuttle missions, in which women have a significantly higher incidence of presyncope during stand tests than do men. The most common observation across disciplines is that individual differences in physiological responses within genders are usually as large as, or larger than, differences between genders. Individual characteristics usually outweigh gender differences per se. physiological responses; health issues THIS MINIREVIEW PROVIDES a summary of gender-specific physiological changes and health issues in astronauts. It is derived from a special task-force report prepared by discipline experts to aid management in policy decisions and selection of research needed to understand gender differences in responses to spaceflight. Histor-ically, investigations of physiological responses to microgravity have not been aimed at examining genderspecific differences in the astronaut population. Many of the discipline experts, however, identified one or more potential gender-specific physiological differences.
Effects of sex and gender on adaptation to space: musculoskeletal health
Journal of women's health (2002), 2014
There is considerable variability among individuals in musculoskeletal response to long-duration spaceflight. The specific origin of the individual variability is unknown but is almost certainly influenced by the details of other mission conditions such as individual differences in exercise countermeasures, particularly intensity of exercise, dietary intake, medication use, stress, sleep, psychological profiles, and actual mission task demands. In addition to variations in mission conditions, genetic differences may account for some aspect of individual variability. Generally, this individual variability exceeds the variability between sexes that adds to the complexity of understanding sex differences alone. Research specifically related to sex differences of the musculoskeletal system during unloading is presented and discussed.
Assessment of the Psychophysiological State of Female Operators Under Simulated Microgravity
Frontiers in Physiology, 2022
The article describes methods of non-verbal speech characteristics analysis used to determine psychophysiological state of female subjects under simulated microgravity conditions (“dry” immersion, DI), as well as the results of the study. A number of indicators of the acute period of adaptation to microgravity conditions was described. The acute adaptation period in female subjects began earlier (evening of the 1st day of DI) and ended faster than in male ones in previous studies (2nd day of DI). This was indicated by a decrease in the level of state anxiety (STAI, p < 0,05) and depression-dejection [Profile of Mood States (POMS), p < 0,05], as well as a decrease in pitch (p < 0,05) and voice intensity (p < 0,05). In addition, women, apparently, used the “freeze” coping strategy – the proportion of neutral facial expressions on the most intense days of the experiment was at maximum. The subjects in this experiment assessed their feelings and emotions better, giving more ...
The physiological effects of human spaceflight
Space travel affects all human physiological systems and nearly all travellers. The main threats include muscular atrophy, radiation, and osteoporosis; the latter two of which, plus sleep and behavioural disturbance, being serious enough to threaten mission viability. Although the lowest energy form of space radiation is relatively harmless, beyond near-Earth-space the remaining two of the three forms are dangerous, while the most powerful type can penetrate any known material and destroy cells. Current shielding materials may increase the danger to human tissues, and in any case adds impractical extra launch weight. Thus, with effective shielding being essentially impossible, deep-space astronauts would suffer possibly-severe tissue damage and cancers over extended periods. Since radiation damage is cumulative, there is also a clear relationship between mission duration and extent of cell death including brain cells. Even low-energy radiation affects the nervous system, impeding cognitive function, and otherwise causes uncomfortable conditions leading to injury and disease. Bone demineralisation and related effects are another serious consequence of microgravity. The rate of bone loss is 1-2 percent per month, although 24% has been observed in animals; the mechanisms may involve the 3D shape of protein enzymes which vary depending on force. It is unknown whether the rate of bone loss is constant. Post-flight recovery time exceeds the flight period by at least a factor of 10, and astronauts may never fully recover. Microgravity also causes skeletal-and cardiac-muscle weakening, whereby muscles lose up to 30% of mass and 50% of strength, with long term recovery prospects unknown. The space environment suppresses astronauts' immunity, reactivating latent viruses. Likely factors include radiation and stress. The stress of confinement – even brief periods – causes numerous secondary effects including mood disorders that have been shown to impact mission performance. The greatest source of stress may be one's own colleagues from whom there can be no possibility of respite. The space environment also affects sleep, which seriously impacts health as well. The true extent and nature of synergistic combinations is virtually unstudied and unknown, although one clear example is space appendicitis. Even the few realistic mitigation options would have at best a mild and temporary effect of no real consequence. Thus, given current and realistically foreseeable spacecraft technologies, the chances of landing on Mars a crew capable of performing complex intellectual or physical work are virtually nil.
Proceedings of the Human Factors Society annual meeting, 1992
A major factor in determining the success of any manned long duration space mission will be how well the human body can endure the microgravity environment. Data collected from long duration space missions conducted by both the United States and the former Soviet Union have shown that almost every system in the human body is adversely affected by microgravity. These adverse affects, taken individually or in concert, can have operational implications for a long duration space mission. Data collected to date indicate that significant human factors complications could arise due to the deconditioning of the musculoskeletal, cardiovascular and hematological systems that occur in a microgravity environment, resulting in decrements in overall astronaut performance. This paper examines some of these deconditioning effects, their immediate operational implications and possible countermeasures.
Objective: The incidence of postflight orthostatic intolerance after short-duration spaceflight is about 20%. However, the incidence after long-duration spaceflight was unknown. The purpose of this study was to test the hypothesis that orthostatic intolerance is more severe after long-duration than after short-duration flight. Methods: We performed tilt tests on six astronauts before and after long-duration (129 -190 days) spaceflights and compared these data with data obtained during stand tests before and after previous short-duration missions. Results: Five of the six astronauts studied became presyncopal during tilt testing after long-duration flights. Only one had become presyncopal during stand testing after short-duration flights. We also compared the long-duration flight tilt test data to tilt test data from 20 different astronauts who flew on the short-duration Shuttle missions that delivered and recovered the astronauts to and from the Mir Space Station. Five of these 20 astronauts became presyncopal on landing day. Heart rate responses to tilt were no different between astronauts on long-duration flights and astronauts on short-duration flights, but long-duration subjects had lower stroke volumes and cardiac outputs than shortduration presyncopal subjects, suggesting a possible decrease in cardiac contractile function. One subject had subnormal norepinephrine release with upright posture after the long flight but not after the short flight. Plasma volume losses were not greater after long flights. Conclusion: Long-duration spaceflight markedly increases orthostatic intolerance, probably with multiple contributing factors.