Postradiation changes in the thyroid gland and skeletal muscle after exposure to iodine-131

The functional status of rat skeletal muscles was studied at dormancy and during the intensive muscular work under conditions of repeated administration of iodine 131 in doses causing reversible and irreversible damages to thyroid gland (the absorbed doses were from 0.27 to 266 Gy). The biochemical changes in muscles were transient; they correlated with the thyroid gland status and lifetime of animals and were displayed during the first 15 days and 2-12 months after the start of the isotope injection.     

Neuroimmunoregulatory properties of short protein fragments in rats exposed to immobilization stress

The influence of short protein fragments on immobilization stress-induced alterations in neuroendocrine and immune systems (catecholamine content in the striatum, hypothalamus and adrenals, serum corticosterone concentration, specific antibody producing activity) was investigated. Immunoglobulin G fragments--tuftsin, rigin, polar amino acid set--polarin and thymus hormone fragment--thymopoetin, as well as substance P (as reference drug) were administered intraperitoneally at doses of 100 and 500 micrograms/kg 30 min before exposure to stress. Rigin and thymopentin showed high stress-protective activity. It is suggested that similar protein fragments, being endogenously formed, may play a regulating role in neuroimmunological homeostasis during exposure to stress.     

Pulmonary xanthine oxidase activity of rats exposed to prolonged immobilization stress

This study was designed to study xanthine oxidase (XO) and xanthine dehydrogenase (XD) activity in the lung of rats exposed to prolonged restraining immobilization stress. Immobilization caused more than twofold increase of xanthine oxidase activity in the rat lung. The activity of xanthine oxidase decreased in lung homogenates incubated at -20 degrees C for 24 h. The same incubation of homogenates from control rats caused a non-significant increase of the activity. No measurable NAD(+)-dependent xanthine dehydrogenase activity could be established in the lungs of both control rats and rats subjected to immobilization. All rats revealed methylene blue-dependent xanthine dehydrogenase activity which was more than two-times higher in the immobilized animals. Incubation at -20 degrees C for 24 h increased the methylene blue-dependent xanthine dehydrogenase activity in homogenates from control rats and decreased the enzyme activity in homogenates from immobilized rats. A working hypothesis was proposed for the sequence of events explaining the results obtained: XO-catalyzed generation of activated oxygen species may take place in the initiation of lipid peroxidation in the lung of rats immobilized for prolonged periods of time.     

Physiological changes in rats exposed to cold/restraint stress.

An investigation was made into the effects of cold/restraint stress in rats on renal function, plasma constituents, blood count and endocrine function. Cold/restraint caused an increased volume of urine output, with increased K⁺ and urea excretion, and decreased Na⁺ and Cl^? excretion. There was a fall in plasma glucose, and a rise in plasma urea. A marked leucopenia was found, and the blood pH was significantly lowered. Cold/restraint was also found to cause marked increases in corticosterone and thyroxine levels, and a fall in the insulin level.     

Effect of naloxone on hypoalgesia in rats exposed to prolonged immobilization stress

Significant hypoalgesia (tail-flick reflex at 60 degrees C) was observed in rats during the whole period of 24-hour immobilization in cramped cages, as compared to food-and-water deprived and control animals. This hypoalgesia was not antagonized by naloxone (1 mg/kg), however, the animals periodically receiving the drug during immobilization revealed aggressiveness and significant hypoalgesia after immobilization was discontinued (30-120 min observation).     

Morphologic changes in the pineal gland of rats exposed to continuous darkness

We examined the pineal structure of rats exposed to constant darkness (DD) at light microscopic level. Two groups of rats were exposed to 12:12 light/dark cycle (LD) or DD from their prenatal ontogenesis and then for 3 months after birth. The gland structure of DD rats was observed to have an active appearance. Some of the observed pinealocytes with light nuclei from DD rats were determined to contain double nucleoli. Nuclear area and perimeter of both dark and light types were greater in rats kept in DD than in LD. Rats exposed to DD had more cells with light nuclei and lesser cells with dark ones than rats kept in LD. No significant differences in nuclear characteristics of intermediate type were found between rats kept in LD and those kept in DD. The activity of mammalian pineal can be altered by light conditions to which the animal is exposed.     

Physiological and structural changes of the lung tissue in male albino rat exposed to immobilization stress

In case of a life-threatening, stressful event, the body prepares for an emergency. Indeed, the lung is unique in which alveolar cells are constantly exposed to physical and chemical stresses. This study aimed to study the impact of immobilization stress on the blood–air barrier and how it initiate and maintain an inflammatory response, plus determining the resolution of lung inflammation and repair. There was a significant increase in the plasma levels of stress markers “corticosterone and catecholamines” with a decrease in surfactant protein A (a lung-injury marker). Chronic stress produced a significant increase in the pulmonary oxidative and inflammatory markers malondialdehyde, tumor necrosis factor α, and induced nitric oxide synthase when compared with that of acute stress. Both stresses provoked marked pulmonary morphological and ultrastructural changes with a significant increase in caspase-3 immunoexpression. There was increasing evidence of lung’s capacity for repair. This process involved edema resolution, cell proliferation, and tissue remodeling in improving the lung-injury, oxidative, and inflammatory markers.     

Change in temperature in young and old rats exposed to emotional-noise and immobilization stress]

Experiments with rats have shown that thermoregulation under normal conditions and in response to stressful factors (immobilization, emotionally significant sound) is different in animals of different age. The effect of these stressful factors leads to more significant temperature changes in the group of young animals, as compared with the adult ones.