Formation of nicotine addiction in mongrel white rats

A study was made of the possibility of forming nicotine addiction in laboratory rats and using it as the basis for the design of experimental nicotine toxicomania. Experiments were carried out on 56 rats placed in individual cages with a possibility of free choice between water and 0.005% nicotine solution for 2 to 4 months. It was established that the population of intact laboratory rats with 8- and 16-week contact with nicotine solution could be divided into groups demonstrating 3 main types of attitude toward nicotine: aversion (68% of all the animals), moderate addiction (4%), and pronounced addiction (28%). These quantitative relationships remained unchanged whatever the time of contact with nicotine. Thus, the possibility has been shown of designing experimental nicotine toxicomania with marked elements of physical dependence in rats consuming nicotine on a voluntary basis.     

Hepatic microsomal mixed-function oxidases in rats exposed to high ambient temperature

Exposure of rats for 3 h or 6h to 28 degrees C or 37 degrees C led to changes in mixed-function oxidases in liver microsomes as compared with 21 degrees C. The complex pattern of the behaviour of the activities of aniline hydroxylase, 4-nitroanisole-O-demethylase, aminopyrine N-demethylase and NADH: cytochrome c oxidoreductase was not related to the observed decrease of cytochrome P-450 and cytochrome b5 contents.     

Circadian and seasonal rhythms in the radiosensitivity of mongrel white rats

From experiments in albino mongrel rats it is shown that the radiosensitivity of gamma-irradiated (60Co) animals follows a daily rhythm. A synchronization of the daily rhythms in radiosensitivity was noted in winter and during the first spring month which was impaired in April. Established were the rhythms of radiosensitivity for three seasons, i. e. winter, spring and summer, with the extremes in the dependence upon mean annual values varying significantly.     

Liver and brain mitochondrial ATPase activities in rats exposed to high ambient temperature

Liver and brain mitochondrial ATPase activities in rats exposed to high ambient temperature. Acta physiol. pol., 1985, 36 (3): 185-192. Rat liver and brain mitochondrial ATPase activities were investigated after a single exposure (6 h) of the animals to temperatures of 21 degrees, 28 degrees and 37 degrees C. An increase of ATPase activity stimulated by Ca++ ions was noted in the mitochondrial fractions of the liver at 28 degrees C and of the brain at 28 degrees and 37 degrees C. Only in liver mitochondria of rats exposed to 28 degrees C a depression of Mg++-ATPase activity was found.     

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.     

Myocardial hypertrophy in rats exposed to simulated high altitude

Myocardial hypertrophy in Sprague-Dawley adult rats exposed to hypobaric hypoxia (0.40 atmosphere of air/18 h daily for 7 days) in a hypobaric chamber was investigated. Changes in the myocardial mass were evaluated on the basis of the dry heart weight and expressed as mg/100 g of total body weight (mean +/- SEM). Data are presented indicating that: chronic hypobaric hypoxia causes a significant degree of myocardial hypertrophy in rats; hypertrophic process involves both ventricles (the right more than the left); removal of the hypoxic stimulus leads to the disappearance of hypertrophy when evaluated as an increase in dry heart weight; hypoxia affects the synthesis of a significant amount of connective tissue in the left ventricle, which is not exposed to pressure load. The r?le of neurohumoral factors (i.e., adrenergic stimulation and catecholamines) in the development of the ventricular hypertrophy is suggested.     

A quick method to screen high and low yielding wheat cultivars exposed to high temperature

In tropical countries, high temperature stress is the major abiotic stress, which controls the productivity and yield of crop plants. Two high yielding and low yielding genotypes of durum wheat were selected for detailed analysis of their photochemical efficiencies. In low yielding genotypes (Malvi local and Sawer local), the whole primary photochemical reactions are affected before and after heat stress. The results show that low yielding genotypes show less efficiency in the usage of the available excitation energy. This is a case study to establish use of chlorophyll a fluorescence measurement as an effective tool to screen plants for their stress tolerance. The study is important for stress physiology and may be useful for assessment of stress tolerant plants.     

Modification of hepatic proteins in rats exposed to high oxygen concentration

The effect of high concentrations of oxygen on cellular proteins was examined in hepatocytes isolated from rats exposed to 100% oxygen for 0, 24, 48, or 54 h. Previous studies have demonstrated that protein oxidation mediated by mixed-function oxidase systems is accompanied by the formation of protein carbonyl derivatives that can be detected by the formation of protein hydrazone derivatives on treatment with 2,4-dinitrophenylhydrazine (DNPH). In these studies the levels of DNPH-reactive proteins increased steadily during 48 h of continuous oxygen treatment and then decreased to control levels by 54 h. Although the specific activity of two hepatic enzymes, glutamine synthetase and glucose-6-phosphate dehydrogenase, decreased during oxygen treatment, antibody titration of each enzyme indicated that the levels of immunological cross-reactive protein either remained constant or increased slightly during 48 h of oxygen treatment. After 54 h of oxygen exposure the levels of immunologically cross-reactive material were significantly reduced. These results suggest that exposure of rats to high concentrations of oxygen leads to the oxidative inactivation of enzymes and the accumulation of oxidized proteins that are subsequently degraded.     

Quantitative study of behavioral disturbances in rats exposed to high pressure

When human divers or experimental animals are exposed to high pressure, they develop the High Pressure Neurological Syndrome (HPNS). Male Sprague-Dawley rats were exposed to high pressure in a conventional helium-oxygen breathing mixture to 80 bars. Pressure-induced behavioral motor disturbances including hyperlocomotor activity (HLA), tremor and myoclonia were monitored with a noninvasive piezoelectrical sensor device enabling a without discontinuity long-term analysis. New data were obtained on the development of the HPNS behavioral motor disturbances. Indeed, the present results suggest myoclonia would be more sensitive to constant high pressure exposure, while HLA and tremor would be more sensitive to increasing pressure. Moreover, myoclonia were found to occur significantly later in rats which developed epileptic seizures than in other. The present results constitute the quantitative basis of HPNS motor disturbances for future pharmacological pressure experiments.     

Dietary GABA and food selection by rats

To obtain further information pertaining to amino acid-induced alterations in feeding behavior, studies were performed to examine the food choices made by rats fed low protein diets made more or less aversive by the addition of various amino acids. When rats were allowed to choose between two diets, they preferred a low protein control, threonine-imbalanced or nonprotein diet to one containing 2.5% gamma-aminobutyric acid (GABA). Acceptance increased when GABA content was lowered to 1.5%; rats preferred this diet when the alternative diet was made sufficiently aversive. There were large individual differences among rats selecting from pairs of unacceptable diets. Avoidance of, or preference for, a given diet is clearly affected by the relative aversive qualities of the offered pair of diets.     

Disorders of vaginal development in the progeny of white rats exposed to x-ray irradiation

One hundred and twenty white rat embryos 13-22-day-old have been irradiated with x-rays (the dose 250 R) on the 12th-14th day of embryogenesis. The embryos have been divided into series of sagittal, frontal, transversal sections and stained by means of general histological methods. The irradiation performed on the days mentioned does not affect formation of the paramesonephric ducts. In all the experimental animals the caudal end of the paramesonephric duct is separated from the mesonephric duct as a solid cellular cord in which the lumen appears later. In the experimental females the disturbances developed after irradiation are manifested first of all in retardation of the main stages of the organ's formation; the retardation is observed: in fusion of the paramesonephric ducts, in resorption of the medial septum between the fused ducts, in separating the sinuous part of the vagina from the urogenital sinus, in recanalization of the vaginal epithelial cord. More severe lesions are presented as agenesia of the vaginal sinuous part and as its atresia represented by a transversal septum of the organ. The disorders in the vagina development are depended on massive primary necrobiotic radial lesions of the mesenchymal cells around the epithelial anlages of the small pelvis.     

Changes in the oxidation-reduction system of glutathione--glutathione reductase [NAD(P). H] in the blood and tissues of white rats exposed to high and low temperatures

The content of different forms of glutathione and the NADPH-dependent glutathione reductasa activity in blood, brain, liver and sceletal muscle of the white rats exposed to low and high temperatures have been investigated. It was shown that in general cooling of animals the amount of glutathione in blood, brain and liver increases, the glutathione reductasa [NAD(P)H] activity decreases. Under super-heating conditions concentration of all forms of glutathione in blood and tissues and the glutathione reductasa activity reduce. Data obtained permitted to assume the considerable role of the changes of the glutathione-glutathione reductasa system state in the realization of temperature factors action.