[STUDIES OF THE ANTIHYPOXIC AND ANTIAMNESTIC EFFECTS OF MELATONIN IN ANIMALS].

Experiments with mice showed that in a multitude of acute hypoxia models (normobaric hypoxic hypoxia with hypercapnia, hypobaric, hemic and histotaxic) the antihypoxic action of a single intra-abdominal dose of melatonin surpasses greatly amtisol, the standard antihypoxic agent. Single melatonin injection produced a strong antiamnestic action on various amnestic models (scopolamine-induced, acute normobaric hypoxia with hypercapnia, and a combination of extreme factors) which was much better than of pyracetame, a well-known nootropic (mind-stimulating) drug. Increase of the melatonin dose from 1 mg/kg to 20 mg/kg amplified both the antihypoxic and antiamnestic effects.

[VESTIBULAR AND THERMOPROTECTIVE PROPERTIES OF A NEW ACTOPROTECTOR].

In experiments with rats, a new 3-hydroxypyridine (3-HP) derivative--2-ethyl-6-methyl-3-hydroxypyridine L-asparaginate (30 mg/kg)--exhibited a strong vestibuloprotective effect which was better than of promethazine (50 mg/kg), a well-known vestibuloprotector Besides the new actoprotector was competitive with another 3-HP derivative, namely, mexidol (ethyl-methyl-hydroxypyridine succinate) (100 mg/kg). Moreover, a distinct thermoprotective effect of 2-ethyl-6-methyl-3-hydroxypyridine L-asparaginate (30 mg/kg) in mice was not worse than that of mexidol or metaprot (ethylthiobenzimidasol, former name bimethy), an actoprotector with good thermoprotective properties. To conclude, owing to the membrane-protective and antioxidative qualities, the vestibuloprotective and thermoprotective properties of 2-ethyl-6-methyl-3-hydroxypyridine L-asparaginate are better or competitive with the reference preparations.

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.

Effects of space flight on Xenopus laevis larval development.

Fifty-three fertilized Xenopus laevis embryos at early tail bud stage were launched into orbit aboard a Biocosmos satellite and remained in microgravity for 11.5 days. During this period, the embryos hatched and continued to develop as free-living larvae.