Relation between the parameters of lipid peroxidation and the constant potential of the rat brain

Studies were carried out of the relationship between the constant potential level (CPL) and the intensity of lipid peroxidation (LP) of the brain membranes in rats with different motor asymmetry. Strong correlation was found between CPL and the content of LP products (diene conjugates, hydroperoxides and Schiff bases) in the hemispheres of the brain (R = 0.7-0.8).     

Basic principles of structural asymmetry of cortex formations in the human brain

Studying the cytoarchitectonical asymmetry of human brain cortex requires using the new approaches and modern quantitative methods. One of the promising ways is analyzing relation between the macroscopic and neuronal structure of the brain. The present article contains original data of histological and morphological studies. The authors develop the concept of different degree of expression of asymmetry in the cortex formations of left and right hemispheres. The data on the principal differences of topography and types of structure of fissure and gyrus in different brain hemispheres are presented. Results of the analysis carried out enable one to show the basic criteria of peculiarities of cytoarchitecture of human brain cortex in the left and right hemispheres.     

Overhauser-enhanced magnetic resonance imaging characterization of mitochondria functional changes in the 6-hydroxydopamine rat model

Oxidative stress may be involved in the dopaminergic neurodegenerations seen in 6-OHDA-lesioned rats through its production of free radicals and through mitochondrial dysfunction. In this study, we noninvasively demonstrate brain redox alterations in 6-OHDA-lesioned rats using Overhauser-enhanced magnetic resonance imaging (OMRI). The reduction rate of 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-l-oxyl (methoxycarbonyl-PROXYL), a redox-sensitive contrast agent, was used as an index of the redox status in vivo. The methoxycarbonyl-PROXYL reduction rate, calculated from continuous images, decreased significantly in lesioned hemispheres compared to their corresponding contralateral hemispheres. The reduction rates in cellular fractions obtained from the striatum were estimated by X-band electron spin resonance (ESR) and calculated by assuming first-order kinetics for their time-dependent decreases. When methoxycarbonyl-PROXYL was mixed with cytoplasm fractions, the reduction rates were the same in both hemispheres. However, the ESR signal of methoxycarbonyl-PROXYL in the mitochondrial fraction of the lesioned hemispheres decayed more slowly than that of the corresponding contralateral hemispheres. Concordantly, biochemical assays showed that the activity of mitochondrial complex I also decreased more slowly in lesioned hemispheres. Thus, this method of noninvasively imaging brain redox alterations faithfully reflects changes in mitochondrial complex I activity in 6-OHDA-lesioned rats.     

Synthesis of S100 Protein on Free and Membrane-Bound Polysomes of the Rabbit Brain

Abstract: Free and membrane-bound polysomes were isolated from the cerebral hemispheres and cerebellum of the young adult rabbit. The two polysomal populations were translated in an mRNA-dependent cell-free system derived from rabbit reticulocytes. Analysis of the [³⁵S]methionine-labeled translation products on two-dimensional polyacrylamide gels indicated an efficient separation of the two classes of brain polysomes. The relative synthesis of S100 protein by free and membrane- bound polysomes was determined by direct immuno-precipitation of the cell-free translation products in the presence of detergents to reduce nonspecific trapping. Synthesis of S100 protein was found to be twofold greater on membrane-bound polysomes compared with free polysomes isolated from either the cerebral hemispheres or the cerebellum. In addition, the proportion of poly- (A+)mRNA coding for SlOO protein was also twofold greater in membrane-bound polysomes compared with free polysomes isolated from the cerebral hemispheres. These results indicate that the cytoplasmic S100 protein is synthesized predominantly on membrane-bound polysomes in the rabbit brain. We suggest that the nascent S100 polypeptide chain translation complex is attached to the rough endoplasmic reticulum by an ionic interaction involving a sequence of 13 basic amino acids in S100 protein.     

Protein Turnover in Brain of the Rat Fetus

Protein synthesis in vivo was studied in whole brain of rat fetuses using continuous intravenous infusion of L-[U-14C]tyrosine into unrestrained pregnant rats at 19 and 21 days gestation. Protein degradation (KD) was calculated by subtracting fractional growth rate of brain protein (KG) from the fractional synthesis rate (KS). KS was high at both gestational ages (0.42 +/- 0.03 days-1 at day 19, 0.47 +/- 0.029 days-1 at 21 days), comparable to values previously reported for newborn rat cerebral hemispheres, and threefold higher than is seen in adult animals. KD was similar at both 19 and 21 days gestation (0.19-0.24) and lower than that reported in neonatal rat brain using similar techniques. Protein accretion during the most rapid phase of brain growth (fetus) is accomplished by similar rates of protein synthesis, but decreased rates of degradation when compared with a slower growth phase (newborn). KD in the brain of the rapidly growing fetus is slightly higher than in adult cerebral hemispheres.     

Lateralized ultradian rhythms of the right and left brain: temporal variations of tactile discrimination tested in German subjects.

Endogenous ultradian rhythms with a periodicity of 2-3 hours operate separately in the right and left hemispheres of the human brain and modulate physiological functions, perception and cognition. Since sensory pathways from either hand terminate in the contralateral hemisphere, ultradian rhythms of the right and left brain can be monitored by variations in the tactile discrimination of the left and right hand, respectively. Thirteen right-handed German males were tested every 15 minutes for 8 hours. Time series of the tactile error rate determined for the right and left hands oscillate with significantly different ultradian periodicities. Whereas cycles in tactile discrimination of the right hand (left hemisphere) have a periodicity of about 2 hours, tactile discrimination of the left hand (right hemisphere) is modulated by longer periods of about 3 hours. This is interpreted in terms of the overall functional asymmetry of the human brain. Since the left brain is the specialized locus for verbal processing and the right brain for visual-spatial processing, lateralized ultradian rhythms operating in the hemispheres may provide a distinct frame for long-term timing of neuronal processes underlying semantic and spatial mapping of the environment. This is particularly important for interpreting biosocial behavioural rhythms seen in humans living under natural conditions.     

The development of superficial infraslow potential oscillations of the brain in chick embryos.

The development of superficial infraslow potential oscillations (ISPO) of brain hemispheres, cerebellum and optic lobes was studied in chick embryos between day 9 and 21 of incubation. The ISPO were firstly registered in brain hemispheres at day 10 of incubation, i.e. 5 days before the onset of spontaneous EEG activity. The ISPO in 10-day-old embryos had an average frequency of 9.9 c/min and an amplitude of 0.14 mV. During further development till hatching the frequency decreased to 7.5 c/min and the amplitude increased to 1.39 mV. Similar ISPO with the same developmental trend were also registered from the surface of the cerebellum and optic lobes. Superficial ISPO were not synchronized either between both hemispheres or between different fields of the same hemisphere.     

Fatty acid composition of brain hemispheres of spontaneously hypertensive rats suckled by female Wistar rats

Total lipid fatty acid composition was investigated in brain hemispheres of male Spontaneously Hypertensive Rats (SHR), compared with normotensive Wistar Kyoto rats (WKY) used as controls. Both strains were suckled by adoptive Wistar mothers, and then fed a standard diet after weaning. No difference was observed between the two hemispheres of WKY killed either at 10 or 30 days. In SHR killed at 10 days, the two hemispheres showed differences, SHR left hemispheres exhibiting greater fatty acid composition changes than those of WKY, phenomenon that toned down at 30 days. Hence, SHR pups showed a different total lipid fatty acid composition of their brain hemispheres when compared with their WKY controls, though the two strains received the same diet. Genetically programmed hypertension might be, directly or not, involved in these changes.     

Expression of erythropoietin receptor mRNA in mouse brain hemispheres

Now there is a growing evidence that erythropoietin receptors (Epo-R) are present also in some nonhematopoietic tissues such as endothelial cells and fetal cells of neural origin, although the physiological role of Epo-R at these sites is unclear. There are some speculations that Epo-R may be expressed on cells only in the developing CNS. The objective of this study was to determine whether Epo-R mRNA may be expressed in the brain hemispheres of Balb/c mice of different age groups: 1) newborn mice, 2) young 2 months old mice, 3) old 1.8 year old mice. We also studied the in vivo effect of recombinant erythropoietin on the expression of Epo-R mRNA in the brain hemispheres of (CBA x C57BL)F1 mice by RT-PCR. We have detected the existence of Epo-R mRNA expression in brain hemispheres of all the groups, but in old mice this expression was significantly higher. We have discovered a decrease in Epo-R mRNA expression in brain hemispheres of (CBA x C57BL)F1 mice 24 h after in vivo administration of recombinant erythropoietin. The Epo-R mRNA expression in the left brain hemispheres of (CBA x C57BL)F1 was considerably higher than in the right one.     

Cerebral blood flow in the fetal guinea-pig

To measure brain blood flow in the fetal guinea-pig, radioactive microspheres were injected in the lateral saphenous vein whilst a reference sample of blood was withdrawn from the right axillary artery. Measurements were made near term of pregnancy, on the 60th-66th day, during anaesthesia with pentobarbitone and diazepam. Fetal blood pressure was 4.25 +/- 0.12 kPa and fetal heart rate was 250 +/- 7 beats per min. The arterial oxygen content varied between 1.9-5.1 mmol 1(-1). Blood flow to the whole brain (mean 1.13 +/- 0.14 ml min-1 g-1) was significantly correlated to the reciprocal of arterial oxygen content (r = 0.84). Four regions of the brain were examined: the cerebral hemispheres, the cerebellum, the thalamus and midbrain, and the pons and medulla. In each region blood flow was inversely related to arterial oxygen content (r = 0.80-0.83) but the rate of perfusion of the brain stem was greater than that of the cerebral hemispheres or cerebellum.     

Messenger RNA coding for glutamine synthetase in cerebral hemispheres and astroglial cultures from mouse brain: A developmental study

Messenger RNAs from mouse brain hemispheres and from an enriched astroglial population of the same area were isolated, characterized and used to study Glutamine Synthetase (GS) processing during postnatal development using a m-RNA stimulated reticulocyte lysate system.The RNA preparations yielded distinct polypeptide products upon translation including high molecular weight species. Polypeptides in the range of 43–55 kDa appeared developmentally regulated in brain hemispheres but not in astroglia. After immunoprecipitation of the translation products with a GS antibody a major monomeric polypeptide was isolated on SDS/PAGE which migrated at the same position as the purified brain GS antigen (43 kDa).The translatable mRNA were optimal in the perinatal period and decreased until 300 days while GS-mRNA increased during the same period of time and closely paralleled the previously described GS activity profile in this brain area reaching an optimum at 15 days. Astroglial mRNAs were optimal at 18 days in vitro and decreased thereafter. The GS-mRNA was much lower in control astroglial cultures than in brain tissue, but in the presence of 10⁻⁶M hydrocortisone increased all over the growth period. The highest stimulation of GS-mRNA was observed at 18 days whereas the global mRNA decreased in the presence of the hormone.The GS-mRNAs from either 15-day-old brain hemispheres or 18-day in vitro hydrocortisone stimulated cultures were partially purified on a 5–30% linear sucrose gradient. Two GS-mRNAs, which sedimented respectively at 17S and 23S, were characterized. In addition, based on the profile of total proteins translated in vitro, we estimated that GS-mRNA constituted 0.01% of the brain hemisphere fraction and 0.3% in the astroglial hormone stimulated cells.     

Gamma-glutamyltransferase activity in the developing brain of the rat and the pika Ochotona pusilla

The activity of gamma-glutamyl transferase (GGTF, EC 2.3.2.2) has been investigated in different brain structures (hemispheres, cerebellum, hippocamp, brain stem) of newborn, 3-8-, 15-, 21-30-day and adult rats and piping hare. In both animals, the activity of this enzyme in all the structures investigated increases during ontogenesis. Interspecific differences were found in the increase of the enzymic activity in different brain structures during ontogenesis as well as in the level of the activity in different structures in mature animals.     

Na+,K+-ATPase activity of the subcellular fractions of the rat brain in aging

The Na+, K+-ATPase activity in the homogenate and in subcellular fractions of different parts of the brain of adult and old rats was studied in comparison. The content of cholesterol in the above fractions was also determined. In old age the Na+, K+-ATPase activity in the homogenate and microsomal fraction of the cerebral hemispheres' cortex decreases, while the Mg2+-ATPase activity in the cortex microsomal fraction increases. The age-related Na+, K+- and Mg2+-ATPase activity in the myelin of the stem in the synaptic plasma membranes of hemispheres and the brain stem remains unchanged whereas in the myelin fraction of hemispheres it grows. The content of cholesterol in the brain of old rats as compared with adult ones increases in the microsomal fraction and remains unchanged in synaptic membranes. The possible role of age-related modification of lipid component of plasma membranes in the above changes of Na+, K+-ATPase activity is discussed.     

Comparative evaluation of the biogenic amine level of the brain and the ethanol kinetics in the blood of inbred C57B1/6 and CBA mice

The kinetics of ethanol in blood and the levels of serotonin, noradrenaline, and dopamine in the cortex of cerebral hemispheres, hypothalamus, thalamus, and brain stem were studied in male C57C1/6 and CBA mice characterized by predisposition and non-predisposition to the development of experimental alcoholism. C57B1/6 mice characterized by predisposition to the development of experimental alcoholism demonstrated a high level of serotonin and noradrenaline in the hypothalamus and brain stem and high rate of ethanol elimination from the blood. CBA mice non-predisposed to the development of experimental alcoholism were characterized by a low level of serotonin and noradrenaline in the hypothalamus and brain stem and by low rate of ethanol elimination from blood.     

Rearrangement of the Prefrontal Cortex Neural Activity in Both Hemispheres during Learning

Neuronal activity of both right and left hemispheres of the rat prefrontal brain cortex was recorded in the two-ring maze during animal learning to operate in response to signals. At the beginning of learning, pairwise comparison of neural activity that accompanied correct and incorrect choice of the right and left sides showed significant differences in the left hemisphere and the lack of differences in the right one. With increasing percentage of correct choices during a session of learning, the differences in neuronal responses appeared in the right hemispheres and were reduced in the left one. The opposite trends in rearrangement of the total impulse activity are believed to be related to different roles of hemispheres in the construction of the internal behavioral model.     

Functional asymmerty of the brain and emotions

Different kinds of emotional phenomena are related in a different way with the workings of the left and right hemispheres of the brain. Emotional reactions (phasic emotions), which appear on the basis of a cognitive loading (mental representation, recognition, play, prognostication, watching movies, reading of emotionally colored texts or separate words and so on) and which are tested with the help of electrophysiological methods, activate different regions of the left and right hemispheres of the brain depending on the complexity and novelty of emotiogenic situations as well as on the degree of subject's emotional tension. The tonic emotions individual background-mood, on which depends the emotional estimation (negative of positive) of the presented stimuli or events, are determined mostly by a prolonged, relatively stable, tonic activation of each hemisphere connected with subjects' individual characteristics. The predominance of the left hemisphere activity creates positive emotional background, whereas the predominance of the right hemisphere creates negative background.     

Interstrain differences in the serotonin and 5-hydroxyindoleacetic acid levels in the postnatal ontogeny of C57BL/6J and BALB/cLac strain mice

The content of serotonin and 5-hydroxy-indole-acetic acid (5-HIAA) was determined in the brain stem and hemispheres in 1 and 3 months old C57BL/6J and BALB/cLac mice. The characteristic dynamics of serotonin and its metabolite content related to the age was found in different brain regions and proved to be similar in both the strains, but the rate of serotonin system development in C57BL/6J mice was higher than in BALB/c Lac mice. An intensive catabolism of serotonin, possibly, related to the reaction to new environment was noted in the newborn animals. Sex differences in the rate of serotonin system maturation and serotonin and 5-HIAA content were shown for 12--16 days old mice: 12 days old males were characterized by more intensive metabolism than females while 16 days old males had less serotonin than females.     

Characteristics of the formation of a free-amino acid brain pool in rats differing in their ethanol consumption

The concentrations of free amino acids were studied in the right and left hemispheres, cerebellum and brain stem of AA and ANA strain rats differing in their voluntary consumption of ethanol solutions. Animals of both the strains were shown to be differentiated by distribution, functional utilization and metabolism of some amino acids in the right and left hemispheres, cerebellum and brain stem.     

Alterations of the Eicosanoid Synthetic Capacity of Rat Brain Microvessels Following Ischemia: Relevance to Ischemic Brain Edema

To know the mechanism underlying ischemic brain edema, a time-course analysis of the eicosanoid synthetic capacity of brain microvessels was carried out using unilateral, middle cerebral artery (MCA)-occluded rats. Concomitant with the development of brain edema the synthetic capacity of all products, including cyclooxygenase and lipoxygenase products, increased significantly. Next the effects of 15-hydroperoxyarachidonic acid (15-HPAA) on the synthetic capacity of microvessels were examined. The drug caused a generalized increase of each product, the profile of which was similar to that obtained with ischemic hemispheres, although the ratios of each product differed somewhat among them. The enhanced synthesis of eicosanoids by 15-HPAA was markedly suppressed by radical scavengers such as alpha-tocopherol, hydroquinone, and 1,2-bis(nicotineamide)-propane. Furthermore, the evolution of brain edema was virtually suppressed by the systemic administration of 1,2-bis(nicotineamide)-propane. The above result suggests that the enzyme activity of the arachidonic acid (AA) cascade of microvessels is stimulated by its own products. Such a mechanism will form a vicious cycle that accelerates the accumulation of free radicals within microvessels and thus may play a role in the progressing disruption of the blood-brain barrier (BBB) following ischemia.     

Effects of acute stress on lateralization of lipid peroxidation in the brain depend on the behavioral typology of rats

Using the "emotional resonance test" albino mongrel male rats were separated for their preference to light or dark space during the cry of a "victim" rat receiving footshock. Rats avoiding the cry of a "victim" by moving to the light space were characterized by higher levels of lipid peroxidation (LPO) products. A short footshock resulted in a dramatic LPO decrease in both hemispheres in the brain of all rats under study, but in rats not avoiding the cry of a "victim" (preferring dark space) "left" asymmetry of LPO increased.