[Reproductive function and viability of progeny in female rats under unfavourable influences in run up to puberty].

Wistar female rats were subjected to a 3.5-day water deprivation once a week in the period of 1.5 to 3 months of age. Their progeny was subjected to the same influences during the same period of life. A week later, reproductive function of female rats was evaluated by mating them with normal males. In the experimental groups of both generations, no significant changes were found in number of neonates and their body mass, in maternal behaviour during the lactation period, in postnatal mortality of pups, in their growth and development, in motor activity, physical endurance and behaviour.

[Adaptation to new environments: microgravity].

Review and analysis of the experiments with Wastar rats in microgravity onboard "Cosmos" biosatellites allows to conclude that adaptive potentials of mammals in space flights lasting up to 1/50 th of their life span are enough for rapid elimination of microgravity-induced metabolic and structural alterations on return to Earth, for maintenance of adequate reactions to acute and chronic stressors in the post-flight period, for normal reproductive function and life span. Consideration is given to individual differences in body responses to the micro-g environment.

Ontogenesis of mammals and gravity.

The results of the experiments with Wistar rats in microgravity and 2G hypergravity are summarized. Their analysis allows to conclude that adaptive potentials of adult animals in space flights lasting up to 1/50 of their life span are enough for maintenance of adequate reactions to acute and chronic stressors in the postflight period, rapid elimination of space-induced metabolic and structural alterations on return to Earth, maintenance of normal reproductive function after space flight. In embryological experiments it was demonstrated that during space flight it is possible not only to maintain physiological functions of an adult organism, but to form functions of a developing fetus. The animals that spent the portion of their prenatal development in space flight were capable to go through the entire cycle of postnatal development, up to sexual maturity and reproduction. In ground based centrifuge experiments with 2G it was demonstrated the possibility of realizing, under hypergravity, of all the main stages of prenatal and early postnatal development of rats: fertilization, embryon implantation, fetal development, birth and lactation of progeny. Exposure of rats to microgravity did not reduce their life span post flight. Alterations in biological age of animals were small.

[Growth, reproductive function, and tolerance to load tests in rats under repetitive adverse conditions]. / Rost, reproduktivnaia funktsiia i perenosimost' nagruzochnykh prob u krys pri periodicheski povtoriaiushchikhsia neblagopriiatnykh vozdeistviiakh.

Wistar rats were subjected to a 3.5-day water deprivation once a month in the period of 1 to 10 months of age. The rats' adaptive abilities proved sufficient for compensation of adverse effects, the rats preserved their normal motor activity, emotionality, and orienting behaviour in the intervals between the effects. In the reproductive period, the males manifested a normal sexual behaviour and fertilizing capacity of their spermatozoids. In the end of the experiment, the experimental animals did not differ from the control animals.

[Microgravity, life span and biological age of animals]. / Nevesomost', prodolzhitel'nost' zhizni i biologicheskii vozrast zhivotnykh.

Summarized are author's and literary data about the microgravity effects on life span and biological age of animals obtained in experiments with laboratory rats flown in biosatellites Kosmos. Exposure of rats in the spaceflight microgravity as long as 3 wk. (up to 1/50th of the life period of this species) did not reduce the life span post flight. Alterations in biological age as judged by the reproductive function, general resistance and tissue regeneration rate were minor and in a number of parameters were significantly less as compared with the shifts resulting from simulation of the physiological effects of microgravity in laboratory (for a similar period). Prospects of investigations into this problem are considered.

Comparison of the reactions of male and female Wistar rats. To 5-day exposure to 2G hypergravity.

Number of essential distinctions between male and female rats both before and after 5-day exposure to 2g were observed. These distinctions are not simple quantitative. One gets an impression that males and females have various "strategies" of homeostasis maintenance in the norm and various patterns of adaptive reactions in different situations including 2g hypergravity.

[Microgravity and development of the mammals: problems results prospects]. / Nevesomost' i razvitie mlekopitaiushchikh (problema, rezul'taty, perspektivy).

The author reviews results of 20-yr in-space and laboratory investigations into the effects of hypergravity (2 g) and hypokinesia (immobilization, suspension, water deprivation). It was found out that the compensatory and adaptive potentials of mammalians (Wistar rats) in microgravity are sufficient to let proceed pregnancy, and activate anabolic processes associated with fetus growth and water-salt homeostasis maintenance. In a number of aspects effects of microgravity on the mother-fetus systems appear to be less significant than of various factors on Earth including the conventional models of microgravity. In all types of experiments, fetus state was determined by mother's well-being, compensatory and adaptive potentials. Under the disadvantageous conditions, survival of fetus cost dramatic shifts in mother's organism. Outlined is a long-range program of research on the problem and feasibility of an experiment in which mammalians will pass the overall life cycle in space flight.

Microgravity and aging of animals.

A study of changed gravity effects upon viability, life span and aging is of interest, on one hand, from a practical viewpoint in relation to the growing duration of space missions and on other hand, from a theoretical viewpoint, because gravity is one of the key factors in the evolutionary process on the Earth. In 1978 special conference titled "Space Gerontology" was held. Well known experts in space biology and physiology of aging participated in it. However, all the materiales presented at the conference were based on analogies and on what could be during exposure to microgravity rather than on real data. I shall try to discuss this problem, basing on the results of rats experiments on board "Cosmos" biosatellites and ground based model experiments. Male wistar rats examined after 1-3 weeks exposure to microgravity on board biosatellites demonstrated some changes similar to the signs [correction of sings] of aging, such as decreased motor activity, thymus involution, muscle atrophy, osteoporosis etc. But all these changes were reversible and in rats examined 3 weeks after return to the Earth we did not find any deviations from the controls.

Morphogenesis of asymmetry of rat brain nuclei under normal conditions and during exposure to microgravitation.

Histological and morphometrical analysis of the brain and peripheral analyzers revealed proliferative migration abnormalities of brain development and neuron differentiation in mammals during a space flight, which can limit space exploration.

[The effect of unfavorable environmental factors on the mother-fetus system]. / Vliianie neblagopriiatnykh faktorov sredy na sistemu mat'-plod.

The paper provides a generalization of data and the results of own experiments with Wistar rats in the conditions of hypokinesia, immobilization, water deprivation, hypergravity, weightlessness and other factors affecting mother and fetus as a system. It gives a comparison of reactivity of pregnant and non-pregnant animals under stress, and also of the effects of unfavorable impacts sustained during various phases of ontogenesis: in pubertation period, directly before pregnancy and during various phases of pregnancy. It demonstrated that exposition of pregnant animals to unfavorable conditions is accompanied by significant stress of the compensatory-adaptive possibilities of mother aiming to support of homeostasis of the developing fetus. Clear changes develop in fetus only in case the adaptive possibilities of mother turn out inadequate or when the developing organs of fetus become active components of adaptive reaction of mother-fetus system and compensate for functional inadequacy of some mother's organ. The paper discusses the problem of individual features of resistivity and reactivity.

[The influence of hypokinesia on the mother-fetus system]. / Vliianie gipokinezii na sistemy "mat'-plod".

In experiments with rats effects of hypokinesia on the course of pregnancy and the mother-fetus system were investigated. Immobilization in penal-type cages of female rats on days 8 through to 19 of pregnancy gave rise to significant shifts in mother's organism, i.e. retarded body mass gain, mass reductions in thymus, spleen, liver, some other organs, and adipose tissue. Rates of prenatal fatality in the experimental group were not changed; yet, fetuses were behind the control by the values of body mass, ossification ranges, development of analyzers and other parameters. Quantities of liquid, sodium, magnesium and calcium per one gram of dry tissue were equal in the experimental and control fetuses. Comparison of the data with results of the embryological experiment with rats aboard the space "shuttle" suggests that immobilization is more baneful for the mother-fetus system than microgravity of the same length.

[Effect of weightlessness on rats endocrine system development]. / Vliianie nevesomosti na razvitie neiroéndokrinnoi sistemy u krys.

The histological structure of the brain and spinal cord, visual, olfactory, auditory and vestibular analysers, and endocrine organs (epiphysis, hypophysis, thyroid and parathyroid glands) were investigated in newborn rats delivered by females who had been exposed to weightlessness a half of the pregnancy period. Analysers of the flight animals did not have any marked deviations from the norm. Loci of neurone degeneration resembling porencephaly but less massive were revealed in various brain portions (cortex, hypocampus, metencephalon, spinal cord) of the infant rats developed in space flight. Endocrine studies showed accelerated differentiation of the thyroid cells secreting thyroid hormones, C-cells, and parathyroid cells in most of the infant rats of the flight group. The test animals reduced the size of epiphysis and the number of pinealocytes. Adenohypophysis was found to be smaller with altered spatial distribution of the trabecular system. The changes look quite impressive but do not threaten viability of the animals.

Simulation models of weightlessness in mammalian's developmental program.

NASA: The author briefly reviews 20 years of study of the effects of weightlessness simulation in rat and mouse development. Results of hypokinesia, immobilization, and tail suspension studies are compared with results of studies conducted during space flight. Results of an experiment using 2G on pregnant rats are reported.^ieng

[Adaptive potentials of mammals under conditions of weightlessness]. / Prisposobitel'nye vozmozhnosti mlekopitaiushchikh v usloviiakh nevesomosti.

Review and analysis of experiments with Wistar rats in microgravity allows to deduce that compensatory-adaptive potentials of mammals in space flight lasting up to 1/50th of their life span suffice for rapid elimination of space-induced metabolic and structural alterations on return to Earth, maintenance of adequate reactions to acute and chronic stresses in the post-flight period, demonstration of a stereotype of pre-flight elaborated conditional reflexes and pregnancy dominant, normal reproductive function and life span. Consideration is given to individual differences in body responses to the micro-g environment. A conclusion is made to the effect that the role of individual stamina and reactivity will be gaining in importance with increasing duration of space flights.

[Effect of weightlessness on the mother-fetus system (results of embryological experiment NIH-R1 abroad the "Space Shuttle"]. / Vliianie nevesomosti na sistemu mat'-plod (rezul'taty embriologicheskogo eksperimenta NIH-R1 na korable "Shattl".

Female rats were exposed to weightlessness in the mid-deck of US "Space Shuttle" in the period between days 9 to 20 of pregnancy and examined on Earth post flight. No significant structural anomalies threatening the life and normal development were found in newborn rats carried by mothers under the conditions of weightless exposures. Water, Na, K, Ca, Fe and Cu contents in fetal and placental tissues of the flight animals were not changed. Differences between the flight and ground-based synchronous controls, or the rates of formation of the fetal skeleton were not revealed. Comparison of these data with results of the experiment aboard biosatellite "Cosmos 1514" in which female rats stayed in weightlessness from day 13 to 18 of pregnancy indicates that the two-fold increase of space flight duration did not add changes in the state of fetuses.

[The effect of water deprivation on the mother-fetus system at different stages of pregnancy in rats]. / Vliianie vodnoi deprivatsii na sistemu mat'--plod na raznykh étapakh beremennosti u krys.

Female Wistar rats were exposed to stress (water deprivation) during 3 days starting from the 8th, 14th or 19th day of pregnancy. In all cases serious changes in the mother's organism were observed and they were manifested in the essential delay of body mass increment. The main indexes of reproductive function (the number of alive new-born rats, relationship between males and females in broods) did not change. The signs of lagging behind in development were revealed for experimental groups of new-born rats (less body mass, delay of bone formation) and they were the most pronounced in the group exposed to stress at the 14-17th day of pregnancy. In postnatal period no essential differences between experimental groups and control in terms of teeth appearance, hearing onset, as well as in the indexes of physical endurance were observed. Behavioral reactions of progeny in the "open field" appeared to be changed only for the generation of female rats exposed to stress in the second period of pregnancy and were different on the exposures as of the 14-17th and 19th-22nd day of pregnancy. The results obtained have been discussed in the context of views about critical periods of development.

[Water-salt homeostasis in rats during space flight]. / Vodno-solevoi gomeostaz u krys v usloviiakh kosmicheskogo poleta.

The paper generalized the results of s series of experiments aimed at studying liquid and electrolytes contents in various organs and tissues of rats following 3-week space flights (SF). The results ascertain high reliability of the water-salt homeostasis maintaining system which ensures stable water and electrolytes amounts in the majority of animal tissues in SF. The following alterations appear to be of greatest significance: deduced potassium levels in the heart ventricle tissues in male rats after short-duration (7-9 d) exposure in SF, zero-g-induced degradation of the body ability to bind potassium at injection of isotonic solution KCl into the stomach; redistribution of potassium ions between mother and developing fetuses in space experiments with pregnant animals. Simulated experiments showed that similar shifting of potassium ions in the mother-fetus system may be due not to weightlessness exclusively but other impacts, i.e. they are not specific.

[The redistribution of calcium ions and organic substances in pregnant rats under extreme conditions]. / Pereraspredelenie ionov kal'tsiia i organicheskikh veshchestv u beremennykh krys v ékstremal'nykh usloviiakh.

It was found that under water deprivation the liver, spleen, white and brown fat decreased in weight in rats whereas the weight of the heart, kidneys and uterus with fetuses did not differ from the control. In pregnant rats, water deprivation led to involution of thymus and hypertrophy of adrenals, decrease in the calcium ions content in the liver and kidney and reducing of the liver and some other organs weight. A similar picture was observed during space flight in pregnant rats. The data obtained suggest a redistribution of organic and inorganic substances under water deprivation.