Effect of neurotizing exposures on conditioned reflex activity in the late postresuscitation period in rats

In white rats resuscitated after 10-minutes stop of the blood circulation, conditioned switching over was elaborated on the basis of alimentary and defensive instrumental reflexes and the effect was studied of neurotizing influences. Single application of electrocutaneous pain stimulus in alimentary situation ("collision") led to more expressed disturbances of conditioned activity in resuscitated rats than in intact ones. Differentiation of a signal different from the positive conditioned stimulus only by the height of the tone, was practically not elaborated in resuscitated rats, and the disturbance of the conditioned alimentary reflex to the reinforced signal appearing during differentiation elaboration, was manifest in them to a greater degree. The obtained data testify that even a short-time brain ischemia, accompanied by a fast and full restoration of the neurological status, leads to functional defects of the CNS appearing at subsequent neurotic influences.     

Effects of carnosine on systemic hemodynamics and myocardial metabolism in rats in the early postresuscitation period]

It was demonstrated in experiments on male rats that acute lethal blood loss and subsequent resuscitation after 4- and 6-min clinical death induce lipid peroxidation processes, decreased antioxidant enzyme activity, cause activation of anaerobic glycolysis in the myocardium. This metabolic heart impairment causes hemodynamic instability in postresuscitation period. 25 mg/kg of carnosine injected during resuscitation decreased functional-metabolic heart impairments and hemodynamic disarrangement as well as early postresuscitation lethality. The authors attribute positive carnosine effect to its significant antioxidant activity.     

The autologous intestinal microflora in the postresuscitation period after acute blood loss in rats

In this work the data obtained in the study of intestinal microbiocenosis in rats on the third day of the postresuscitation period after acute blood loss are presented. The quantitative and qualitative shifts of microflora at different biotopes, such as the wall of the small intestine, the parietal microflora of Peyer's patches, the contents and wall of the large intestine, have been characterized. Some specific features of dysbiotic changes have been revealed in comparison with the shifts of intestinal microflora in cases of dysbacteriosis caused by other reasons. The translocation of different microorganisms, including Bacterium bifidum and lactobacilli, into mesenteric lymph nodes, the liver, the spleen and the blood has been observed.     

The effect of low-intensity laser radiation on blood metabolic indices in the postresuscitation period]

The effect of He-Ne laser radiation (632.8 nm; 0.3 mW/cm parallel to oxygenation on metabolism indices of blood, taken in early postresuscitation period after discontinuation of hemorrhagic shock was studied in vitro. Compared to oxygenation alone, combined therapy resulted in more marked oxygen consumption of the blood, normalization of plasma antioxidant total activity, superoxydismutase erythrocyte catalase activity, the number of double connections in fatty acid chain of general lipids and membrane viscosity were elevated. Regular dependence of lipid peroxidation on a number of metabolic blood parameters is revealed.     

Dark and clear Purkinje's cells in the cerebellum during the postresuscitation period

Interference microscopy was used to determine dry mass of the nucleus and cytoplasm of light, dark and morphologically changed Purkinje's cells (PC) of the cerebellum of dogs which had suffered clinical death of varying etiology as compared with intact animals. Two weeks after the 12-minute circulatory arrest the area of the nucleus of both light and dark PC sharply increased. Dry mass of the nucleus of dark PC and of the cytoplasm of both PC types also became greater. Two weeks following the 10-minute clinical death because of acute hemorrhage dry mass of the nucleus and cytoplasm of dark PC increased whereas in light PC it was unchanged as compared to the control level. In morphologically changed PC of dogs belonging to the both experimental groups, dry mass of the cytoplasm was essentially higher than in intact animals. It might be assumed that an increase in dry mass of the nucleus and cytoplasm has bearing on intracellular reparative regeneration. Taking into consideration that in intact dogs, dry mass of the cytoplasm and the concentration of dense substances in the nucleus of dark and light PC are similar, it should be suggested that light and dark PC differ in their roles in the maintenance of the population homeostasis rather than in the metabolic rate.     

C-fos expression in rat brain during heat stress

Rats, under urethane anesthesia, 0, 20, 40 or 80 min after the start of heat stress (42°C) were sacrificed for determination of c-fos expression in different brain regions. In situ hybridization and immunocytochemistry methods were used, respectively, for determination of c-fos mRNA and protein, respectively. In general, either colon temperature (T_CO), mean arterial pressure (MAP), local cerebral blood flow (CBF) or c-fos expression in different brain regions (including the preoptic area, supraoptic nuclei, paraventricular nuclei, thalamus, amygdala, nucleus tract solitarii, area postrema and ventrolateral medulla) increased at 20–40 min after the start of heat exposure. However, the heatstroke, which appears as profound decreases in both MAP and local CBF and increases in T_CO, was produced 80 min after heat stress. The c-fos expression was heavily induced in all these brain regions after the onset of heatstroke. The data suggest that c-fos expression in rat brain during heatstroke is associated with hyperthermia, arterial hypotension or cerebral ischemia.     

Biogenic amines in brain structures of rats of different zoo-social rank during immobilization stress]

The content of monoamines and their metabolites in different parts of the brain: mesencephalic reticular formation, locus coeruleus, sensomotor cortex was studied by high-performance liquid chromatography in rats with different zoo-social position. Content of dopamine and serotonin in the brain structures studied was found to be different in dominants and subdominants. Maximal changes of monoamines under immobilization stress were observed in dominants.     

Differential expression pattern of heat shock protein 70 gene in tissues and heat stress phenotypes in goats during peak heat stress period

It has been established that the synthesis of heat shock protein 70 (Hsp70) is temperature-dependent. The Hsp70 response is considered as a cellular thermometer in response to heat stress and other stimuli. The variation in Hsp70 gene expression has been positively correlated with thermotolerance in Drosophila melanogaster, Caenorhabditis elegans, rodents and human. Goats have a wide range of ecological adaptability due to their anatomical and physiological characteristics; however, the productivity of the individual declines during thermal stress. The present study was carried out to analyze the expression of heat shock proteins in different tissues and to contrast heat stress phenotypes in response to chronic heat stress. The investigation has been carried out in Jamunapari, Barbari, Jakhrana and Sirohi goats. These breeds differ in size, coat colour and production performance. The heat stress assessment in goats was carried out at a temperature humidity index (THI) ranging from 85.36–89.80 over the period. Phenotyping for heat stress susceptibility was carried out by combining respiration rate (RR) and heart rate (HR). Based on the distribution of RR and HR over the breeds in the population, individual animals were recognized as heat stress-susceptible (HSS) and heat stress-tolerant (HST). Based on their physiological responses, the selected animals were slaughtered for tissue collection during peak heat stress periods. The tissue samples from different organs such as liver, spleen, heart, testis, brain and lungs were collected and stored at ?70 °C for future use. Hsp70 concentrations were analyzed from tissue extract with ELISA. mRNA expression levels were evaluated using the SYBR green method. Kidney, liver and heart had 1.5–2.0-fold higher Hsp70 concentrations as compared to other organs in the tissue extracts. Similarly, the gene expression pattern of Hsp70 in different organs indicated that the liver, spleen, brain and kidney exhibited 5.94, 4.96, 5.29 and 2.63-fold higher expression than control. Liver and brain tissues showed the highest gene expression at mRNA levels as compared to kidney, spleen and heart. HST individuals had higher levels of mRNA level expression than HSS individuals in all breeds. The Sirohi breed showed the highest (6.3-fold) mRNA expression levels as compared to the other three breeds, indicating the better heat stress regulation activity in the breed.     

Thermoregulation of nutrient-restricted hair ewes subjected to heat stress during late pregnancy

In summers with severe hot environmental temperatures, thermoregulation is expected to be critical during the last third of gestation of hair ewes, and this effect can be overstated by suboptimal feeding conditions. Twenty-four multiparous hair sheep ewes with approximately 100 d of pregnancy were randomly assigned to two treatments to evaluate the effects of nutritional restriction (NR) during late gestation on some serum metabolites, physiological variables, and thyroid hormone concentrations under intense heat load (maximum temperature 42–45 °C). Treatments were as follows: (1) control, ewes fed free choice wheat straw plus a concentrate at a rate of 500 g/d, and (2) nutritionally-restricted (NR) ewes, which were offered wheat straw only ad libitum. Body weight of NR ewes dropped 5.1 kg (P<0.05), while control ewes gained 4.7 kg during the study period. Rectal temperature was not affected (P>0.05) by feeding regime either in the morning or afternoon hours. Respiration rate was greater (P<0.05) in control ewes (20 and 40 breaths/min higher in the day and night, respectively) on d 130 and 145 of pregnancy compared to NR ewes. Skin temperatures during the morning and afternoon were affected (P<0.05) by feeding regime at d 130 and 145 of pregnancy. In the morning, NR ewes presented greater (P<0.05) head and rump temperature at day 145 of gestation, and lower (P<0.05) udder temperatures at d 130 and 145 than control ewes. In the afternoon, skin temperatures of NR ewes were higher (P<0.05) in head and right flank on d 130 and 145 of pregnancy, and in udder at day 145 compared to control ewes. Serum glucose was higher (P<0.05) in NR ewes than control animals at day 145 of pregnancy. Serum cholesterol, triglyceride and thyroid hormones were not affected by nutritional restriction. Overall, it was found that nutritionally restricted ewes were less affected by intense heat loads than well-fed ewes, apparently due to the lower metabolic heat produced by this underfed animals. Also, it was apparent that the lower respiration rate of NR ewes was compensated by a greater body surface temperature.     

Ultrastructure of the cerebral cortex and hippocampus of rats in the early postresuscitation period following total ischemia

The rat frontal brain cortex and CAr hippocampal region were studied on the 4th day after 10-min complete ischemia. It has been established that the number of "dark" osmiophilic neurons was increased. The reparative, destructive and adaptive processes in cells were observed. The most prominent destructive changes were found in CAr hippocampal region, they can be associated with the microcirculatory disturbances. The hypertrophic thread-like mitochondria appear in the nervous and glial cells, with the quantity of lipofuscin granules increasing. Lipofuscin and hypertrophic mitochondria are thought to provide energy exchange in the brain cells during the postischemic period, forming one of the mechanisms of intracellular adaptation to hypoxia.     

Chronic stress and forming of psychoemotional state during prepubertal period in rats

Immediate and long-lasting effects of chronic stress during prepubertal period (21-32 postnatal days) on anxiety- and depression-related behavior were studied in Wistar and ISIAH (inherited stress-induced arterial hypertension) rats. Significant interstrain differences were found. Both juvenile and adult ISIAH rats were less anxious in the elevated plus-maze and less depressed in the forced swimming test. Immediate effects of the prepubertal stress were similar in both rat strains and depended on the type of stimulation. Long-lasting effects were genotype-dependent. Chronic prepubertal handling exerted an anxiolytic effect in young ISIAH and Wistar rats and adult Wistar rats. Immediate anxiogenic effect of prepubertal unpredictable stress was preserved only in adult ISIAH rats. Depression-related behavior was intensified by the unpredictable stress in young animals, whereas the long-lasting effect was observed only in adult hypertensive rats.     

Toxic activity of the blood plasma in the early postresuscitation period

The time course of blood plasma toxicity was studied in dogs in the early postresuscitation period 10 minutes after clinical death because of acute hemorrhage. The duration of dying, the rate of the recovery of the main vitally important body functions were discovered to affect the rate of accumulation in the blood of substances with different molecular weights. There were 3 phases in blood plasma toxicity accumulation. The first phase is marked by the overflow of blood vessels with low-molecular substances, the second one by relative lessening of the content of low-molecular metabolites and an increase in the content of medium-molecular substances. The second phase is in agreement with the maximal rise of blood plasma toxicity. The third phase that develops by the 60th minute of the postresuscitation period is characterized by reduction of the peak activity of all substances under study and by overt toxicity with relative normalization of the main body functions.     

Collagen synthesis by osteoblasts in the maxilla in rats during the embryonic period]

Under study was the intensity of the collagen synthesis by osteoblasts of the primordium of the rat's maxilla at different terms of embryogenesis. Autoradiographic method revealed that the greatest part of incorporated glycin was used for construction of collagenous molecules, and the least part--for the synthesis of other cytoplasmic proteins of osteoblast. Different intensity of the synthesis of de novo collagen was established at different stages of embryogenesis. The most intensive synthesis of collagen was found to begin from the 18th day of the maxillary bone primordium development.     

Relationship between heat stress during the peri-implantation period and early fetal loss in dairy cattle

The aim of the present study was to establish whether temperature-humidity index values, as a measure of heat comfort, from Days 1 to 40 of gestation could be associated with the pregnancy loss rate in high producing dairy cows. Data from 1391 pregnancies were recorded. Pregnancy was diagnosed by transrectal ultrasonography between Days 34 and 45, and again 90 days after insemination. Pregnancy loss was assumed when the second pregnancy diagnosis on Day 90 proved negative and was registered in 7.8% (108/1391) of pregnancies. Mean and maximum temperature-humidity index values were established for each cow for Days 0 (day of insemination), 1, 2 and 3 after insemination, and averages established for Days 0-3, 0-10, 11-20, 21-30 and 31-40 after insemination. Cow and management variables previously found to be significantly correlated with the early fetal loss in the same geographical area were also recorded. The relative contribution of each factor to the probability of pregnancy loss was determined using logistic regression models. Based on the odds ratio, a strong association with pregnancy loss of the factors warm period of pregnancy (warm period-May to September versus cool-October to April), twin pregnancy (as negative factors: odds ratios 3.1 and 3.4, respectively) and an additional corpus luteum (as a positive factor: odds ratio 0.32) was confirmed. The likelihood of pregnancy loss increased by a factor of 1.05 for each additional unit of the mean maximum temperature-humidity index from Days 21 to 30 of gestation. Logistic regression analysis revealed no significant effects of temperature-humidity index values for the remaining gestation periods. Our results indicate that heat stress can compromise the success of gestation during the peri-implantation period, such that high temperature-humidity index values for the period 21-30 days of gestation are a risk factor for subsequent early fetal loss.     

Ammonia formation in the brain during dying and in the recovery period following resuscitation]

Dynamics of some nitrogen metabolism indices in the brain of dogs during dying and post-resuscitation period was studied in experiments on dogs. Glutamine proved to serve as the main source of ammonium hydrate in the brain during dying and clinical death. In the reconstruction period after revival of the organism glutamine was converted into ammonium eliminator, and the main sources of ammoniogenesis were labile amide protein groups.     

Morphologic changes of the pancreas in hemorrhagic shock and the postresuscitation period

The canine pancreas (20) in the terminal period of hemorrhagic shock and postresuscitation period was studied histologically and electronmicroscopically. There were detected ultrastructural signs of the plasmatic membranes of pancreatocytes and membranes of secretory granules with "leakage" of pancreatic ferments in the interstitial tissue. The incretion of pancreatic ferments in the vascular bed is conditioned by the elevation of proteolytic activity of blood serum in hemorrhagic shock and postresuscitation period.