Effect of artificial gravitation on the skeletal musculature of rats during space flights]

Comparative morphological and histochemical investigation of the rat skeletal muscles after a 18.5 days flight in the space ship "Cosmos-936" under conditions of weightlessness and artificial gravitation created by means of a centrifuge has demonstrated that weightlessness creates muscular atrophy, with fibres of different types affected in different muscles. The greatest changes take place in the soleus muscle. Metabolic disorders in the muscular tissue are manifested as an excessive deposition of glycogen and an increased content of phospholipids in it. The artificial gravitation favourably affects the state of the skeletal musculature preventing the development of metabolic disorders, though it does not completely avert the appearance of atrophic processes in it.     

Electron microscope analysis of cardiomyocytes in the rat left ventricle under simulation of weightlessness effects and artificial gravitation

Electron microscopic study of left ventricle cardiomyocytes and quantitative analysis of their mitochondriom was performed in rats exposed to tail-suspension, as a model of weightlessness effects, to artificial gravity produced by intermittent 2 G centrifugation and a combination of these effects. It was found that the cardiomyocytes ultrastructure changed slightly after tail-suspension and after intermittent 2 G influence, as well as under a combination of these effects. However, the number of intermitochondrial junctions increased significantly in the interfibrillar zone of cardiomyocytes under a combination of tail-suspension and intermittent 2 G influence, which agrees with the cell hypertrophy described earlier.     

Effect of lithium chloride on the thyroid gland of white rats]

The morphological and functional changes in the thyroid tissue of white rats injected lithium chloride at doses 0.5 mekv/kg and 1.0 mekv/kg (groups 1 and 2, respectively) during three weeks were studied by the radiometric, histological and biochemical methods. The radiometric, histological and biochemical methods. The inhibitory action of lithium chloride on hormonogenesis in the thyroid gland and secretion of thyroid hormones into the blood was proved to be directly related to the lithium dose and concentration in the blood. The data of intravital radiometric and morphological analysis of the organs of the 1st group animals suggest some activization of the gland function, with the secretion of the hormones into the blood being suppressed. Increased concentration of the drug inhibits hormonogenesis and secretion of thyroid hormones into the blood.     

Effect of aging on the morphology and function of the thyroid gland of the cream hamster

Summary The effect of aging on the morphology and function of the thyroid gland of the cream hamster was studied by light and electron microscopy coupled with autoradiography or histochemistry.Morphologically, aging induces an accumulation of lysosomal dense bodies and a loss of the phagocytosis of colloid droplets after stimulation with TSH. Iodine uptake and organification occur normally and thyroglobulin synthesis, estimated by autoradiography with ³H-leucine, is not different from that observed in young animals. The basal T₄ and T₃ plasma levels are lower in the old animals. A low iodine diet administered for several months prevents the age related accumulation of lysosomal dense bodies. Hormone secretion seems to proceed by two different mechanisms; phagocytosis of colloid droplets, the classical mechanism that decreases with age, and an additional mechanism, probably micropinocytosis, that is maintained during the whole lifespan.Presented at the First French Congress of Endocrinology, Montpellier, September 1980Work was performed under contracts n 3.4523.79 and n 3.4512.80 of the Fonds de la Recherche Scientifique Médicale, thanks to a grant of the Ministère Belge de la Politique Scientifique (Action concertée) and with the help of the Fondation Interuniversitaire pour la Recherche du Processus du Vieillissement, Belgium     

Studies on quantitative morphology. XII. Distribution of thyroid gland compartments in an activated rabbit thyroid gland

A series of longitudinally cut step sections with a distance of 50 microns of a rabbit thyroid gland was measured by point counting for the relative tissue elements colloid, epithelium, and interstitium. Furthermore, the ratio epithelium:colloid was computed, which was somewhat high, indicating an activated stage. Higher colloid data were found in the outer regions and insignificantly lower epithelium values. Neither the volume data nor the distribution of the structure elements show any difference between both of the lobes. The degree of heterogeneity was comparably low, but only about 30% of all data for the relative colloid percentages or for the ratios are enclosed in a range of +/- 5% in relation to the most accurate value from all hits all over the gland, and about 20% of the ratio data are crossing the +/- 20% borderlines. It was calculated that measuring of not more than 5 sections with approximately equal distances with a very few 10(3) hits yields values of an acceptable accuracy for all parameters and this with a reasonable time expense.     

The ontogenetic model of gravitation and weightlessness: theoretical and applied aspects

In the review we discuss the earlier postulated [1] natural motor strategies which are dependent on gravitation and temperature and which evolve during the human life span. The first of them, FM-strategy is the characteristic of the intrauterine immersion in the amniotic fluid and ofmicrogravitation in the spaceflight (G - 0). It is based on domination of fast muscle fibers and phasic movements and forms the fetal strategy to survive in heating, strongly hypoxic, albeit normal for fetus, immersion. In the adults, adaptive response separately to microgravitation, heat stress and hypoxia also shifts muscle fiber properties to faster values. In accordance with that paradigm the process of parturition can be considered as equivalent to cosmonaut's/astronaut's transition from microgravitation back to Earth gravitation (G = 1) during landing. This new GE-strategy) is opposite to the FM-strategy, because it decreases the motor unit firing and "slows" the activity of muscle fibers. The next, SJ-strategy is the characteristic of normal ageing that causes further dominance of slow motor units, thus simulating hypergravitation (>1G). Cooling evokes similar adaptive reactions. The synergy of sensory inputs which act across the motor system within the above said motor strategies suggests their mutual substitution. Thus, even moderate cooling may serve as partial "surrogate" for gravitation (approximately 0.2G), that could be utilized as a prophylactic countermeasure for unfavorable effects of the long term space flight.     

Effect of carbamylcholine on Harderian gland morphology in rats

Summary To determine the effect of cholinergic secretagogue on the Harderian gland of rats, several light- and electron-microscopic parameters were morphometrically assessed at different time intervals after carbamylcholine injection. In controls, two types of glandular cells (type A cells having 40–55 large vacuoles per cell profile and type B cells containing 30–38 smaller vacuoles per cell profile) and myoepithelial cells were recognized. At 5 min after injection of carbamylcholine, when rats secreted bloody tears, many alveoli showing narrower lumina and exocytotic figures in both types of cells were observed. Some vacuoles, which were covered by thin cytoplasmic sheets, protruded into the alveolar lumina. However, there was no evidence of apocrine or holocrine secretion. At 30 min and 120 min after injection, most of the alveolar lumina were dilated, and a pronounced decrease in the number of vacuoles in the glandular cells was observed. At 300 min after injection, the secretory vacuoles in both cell types reaccumulated. Transitional forms between the two cell types were not observed. The two types of Harderian gland cells can therefore be considered independent populations rather than different secretory stages of the same cell. It appears that the secretory process of the Harderian gland of rat is affected by cholinergic stimulation of the two types of glandular cells and of myoepithelial cells.     

14C-1-Tyrosine metabolism on rat thyroid gland]

Amino acid composition of incubation medium, thyroid tissue hydrolysate and purified thyreoglobulin (Tr) preparations, isolated after 5 hour incubation with 14C-1-tyrosine in Jey medium is studied by means of electrophoresis and autoradiography. 5 radioactivity stains are detected on radioelectrophoregram of incubation medium, 2 of them corresponding to tyrosine and serine. 2 stains corresponding to diiodotyrosine and triiodotyronine are found in hydrolysate of thyroid tissue. No radioactive stains were found on radioelectrophoregrams of thyreoglobulin. The data obtained indicate that in the reaction of condensation of iodotyrosines into iodotyronine a lateral chain of iodotyrosine (serine) splits off. Thyroid hormones biosyntesis takes place by condensation of either a single free molecule of iodotyrosine with iodotyrosyl residue of polypeptide chain of pre-synthesized thyreoglobulin, or two free molecules of iodotyrosine.     

Effect of mesotocin on thyroid gland of the frogRana temporaria

The thyroid gland was studied in intact and hypophysectomized (10 and 60 days before the experiment), sexually mature male frogsRana temporaria after three injections of mesotocin at 30-min intervals (a dose of each injection was 5 ng/g body weight). As determined morphologically, height of the thyrocytes was statistically significantly decreased in intact frogs, while no statistically significant changed were revealed in hypophysectomized animals. The data obtained indicate that at stress responses in frogs, mesotocin can affect the thyroid gland via adenopituitary rather than via general circulation, i.e., by an indirect way.