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Normal distributions of somal volume estimates in rat hippocampus
Poster presentations sessions 1,2,3 / International Journal of Psychophysiology 69 (2008) 207–241
241
individual HRV indices to effects of different mental workload levels and role of heterogeneity for explanation of contradictoriness data of mental workload studies had been analyzed too. The given questions have a greater importance for decision of various ergonomic tasks. In addition, FSC had been used during the simulation of anxious states of operators that has allowed recognizing three dominant functional classes: qEmotional excitementq, qEmotional excitement with predominance of sympathetic activityq and qMental strainq. We proposed that different forms of emotional excitement characterize the anxiety (mobilization) and mental strain states characterize the fear (in readiness to react). We supposed that FSC based on three-factor model of HRV would be useful not only for decision of various ergonomic tasks, but also for diagnosing different emotional states, mental disorders, and for estimation of therapeutic efficacy.
doi:10.1016/j.ijpsycho.2008.05.122
Interaction between glucocorticoids and opiate system on memory retrieval
Conclusion: The absolute distributions of somal volume in the hippocampal region of laboratory animals is a useful parameter in toxicological and phylogenetic studies involving learning and memory function. This study using advances in the field of stereology provided the possibility for a very precise estimation of distributions of somal volume in different subdivisions of the rat hippocampus.
A.A. Vafaei, A. Rashidy-Pour, A.A. Taherian Laboratory of Learning and Memory, Physiology Department and Research Center, Semnan University of Medical Sciences, Semnan, Iran
doi:10.1016/j.ijpsycho.2008.05.557
Extensive evidence indicates that stress and glucocorticoids modulate memory retrieval in both animals and humans, but the underlying mechanisms are not known. It appears that glucocorticoid effects on memory retrieval occur too rapidly to be mediated via the classic genomic action via intracellular receptors. Thus, it is likely that the observed rapid effects of corticosterone on memory retrieval may involve an interaction with several neurotransmitters in the brain including opiate system, dopaminergic system, and noradrenergic transmission in the hippocampus and amygdala through membrane glucocorticoids receptors that are independent from the classical glucocorticoid receptors. In this work, we have pointed on interaction between glucocorticoids and opiate system on memory retrieval processes in both spatial and contextual memories in rats. Our results show that peripheral and intra-hippocampal injections of corticosterone impair retrieval long term memory in different tasks. Peripheral and intra-hippocampal injections of opioid antagonist (Naloxone or Naltrexone) blocked glucocorticoid-induced deficit in memory retrieval. Further, we have demonstrated that the hippocampal kappa opioid receptors don't interact with glucocorticoids in influencing long-term memory retrieval.
Genomic instability in the schizophrenia brain: Highlighting new intracellular mechanism for pathopsychophysiology of brain diseases
doi:10.1016/j.ijpsycho.2008.05.123
Normal distributions of somal volume estimates in rat hippocampus M. Hosseinisharifabad a, J.R. Nyengaard b Yazd University of Medical Sciences, Department of Anatomy,Yazd, Iran b University of Aarhus, Stereology and Electron Microscopy Research Laboratory, Aarhus, Denmark
a
Introduction: In order to evaluate the specific vulnerability of hippocampal neurons to different aggressive agents, it is important to quantify changes in neuronal size. The precise estimation of individual neuron volume allows one to measure the effect of experimental manipulation. This study, for the first time, aimed to determine normal distributions of unbiased somal volume estimates in rat hippocampal subdivisions. Materials and methods: 2-month-old male Wistar rats were anesthetized with urethan and transcardially perfused with a phosphate-buffered solution of (PH = 7.2, M = 0.12) 4% formaldehyde and 1% glutaraldehyde. Each brain was removed and divided into two hemispheres. One hemisphere was selected at random for estimating number of neurons and the other for estimating individual volume of neurons. The total numbers of dentate granule cells (DG) and pyramidal cells (area CA1–3) in the hippocampus were estimated with the optical fractionator. The Rotator method was applied to estimate the individual volume of neurons. Results: The absolute distribution of unbiased somal volume estimates for hippocampal formation is shown in the figure. Vertical bars represent SEM. Each graph is based on approximately 2500 individual somal volume estimates.
Y.B. Yurov a, I.Y. Iourov a, S.G. Vorsanova b, I.A. Demidova b, A.K. Beresheva b, V.S. Kravets b, V.V. Monakhov a, A.D. Kolotii b, I.V. Soloviev a, V.M. Vostrikov a, N.A. Uranova a, T. Liehr c a National Research Center of Mental Health, RAMS, Laboratory of Cytogenetics, Moscow, Russia b Institute of Pediatrics and Children Surgery, Rosmedtechnologii, Moscow, Russia c Institute of Human Genetics and Anthropology, Jena, Germany The most common form of genetic/genomic instability observed in humans is loss/gain of chromosomes in a cell (aneuploidy). It has been recently suggested that aneuploidy directly affecting brain cells could be a possible genetic mechanism for brain diseases with genetic predisposition (Yurov et al., 2001; Iourov et al., 2006). We tested this hypothesis analyzing the schizophrenia brain using modern molecular cytogenetics techniques that allow high-resolution identification of chromosome numbers and structure at single cell level (based on fluorescence in situ hybridization). We have monitored intercellular chromosome number variations in 18 post-mortem brain samples (prefrontal cortex) of schizophrenia individuals and 18 age- and sex- matched controls. We have found that 4 out of 18 cases demonstrate a stable increase mosaic or low-level aneuploidy. In these samples, the rate of aneuploidy for chromosomes 1 or sex chromosomes X in neuronal and glial cells was in the range 2%–7%, affecting totally from 2 to 7 billions of cells in the diseased cortex. Moreover, stochastic rate of chromosomal mutations in the schizophrenia brain was two-times higher that in the unaffected brain. Together, this suggests that, in at least a number of cases, psychopathophysiology of schizophrenia is mediated by genomic instabilities manifested as aneuploidy. These data highlight such intracellular events in the brain as chromosome variations to be an additional genetic mechanism for schizophrenia pathogenesis. Aneuploidy in humans is usually devastative and hallmarks different types of pathology. In common chromosomal syndromes aneuploidy is usually associated with conspicuous brain malformations. However, small proportions of aneuploid cells do not seem to cause morphologically detectable changes, but seriously affect cellular neurophysiology and neuronal network in a whole. It is noteworthy that a neuron is connected to several thousands of other neurons. Therefore, if a neuron has a loss/gain of several thousands genes of a chromosome involved in aneuploidy, it will negatively affects the functions of other neurons as well neuron-glia interaction. This suggests that even peculiar proportion of aneuploid neurons has impressive psychophysiological impact. Finally, further investigations are needed in order to define the incidence of brain specific aneuploidy in schizophrenia as well as more precise definition of aneuploidy impact on physiology of brain cells.
doi:10.1016/j.ijpsycho.2008.05.583
241
individual HRV indices to effects of different mental workload levels and role of heterogeneity for explanation of contradictoriness data of mental workload studies had been analyzed too. The given questions have a greater importance for decision of various ergonomic tasks. In addition, FSC had been used during the simulation of anxious states of operators that has allowed recognizing three dominant functional classes: qEmotional excitementq, qEmotional excitement with predominance of sympathetic activityq and qMental strainq. We proposed that different forms of emotional excitement characterize the anxiety (mobilization) and mental strain states characterize the fear (in readiness to react). We supposed that FSC based on three-factor model of HRV would be useful not only for decision of various ergonomic tasks, but also for diagnosing different emotional states, mental disorders, and for estimation of therapeutic efficacy.
doi:10.1016/j.ijpsycho.2008.05.122
Interaction between glucocorticoids and opiate system on memory retrieval
Conclusion: The absolute distributions of somal volume in the hippocampal region of laboratory animals is a useful parameter in toxicological and phylogenetic studies involving learning and memory function. This study using advances in the field of stereology provided the possibility for a very precise estimation of distributions of somal volume in different subdivisions of the rat hippocampus.
A.A. Vafaei, A. Rashidy-Pour, A.A. Taherian Laboratory of Learning and Memory, Physiology Department and Research Center, Semnan University of Medical Sciences, Semnan, Iran
doi:10.1016/j.ijpsycho.2008.05.557
Extensive evidence indicates that stress and glucocorticoids modulate memory retrieval in both animals and humans, but the underlying mechanisms are not known. It appears that glucocorticoid effects on memory retrieval occur too rapidly to be mediated via the classic genomic action via intracellular receptors. Thus, it is likely that the observed rapid effects of corticosterone on memory retrieval may involve an interaction with several neurotransmitters in the brain including opiate system, dopaminergic system, and noradrenergic transmission in the hippocampus and amygdala through membrane glucocorticoids receptors that are independent from the classical glucocorticoid receptors. In this work, we have pointed on interaction between glucocorticoids and opiate system on memory retrieval processes in both spatial and contextual memories in rats. Our results show that peripheral and intra-hippocampal injections of corticosterone impair retrieval long term memory in different tasks. Peripheral and intra-hippocampal injections of opioid antagonist (Naloxone or Naltrexone) blocked glucocorticoid-induced deficit in memory retrieval. Further, we have demonstrated that the hippocampal kappa opioid receptors don't interact with glucocorticoids in influencing long-term memory retrieval.
Genomic instability in the schizophrenia brain: Highlighting new intracellular mechanism for pathopsychophysiology of brain diseases
doi:10.1016/j.ijpsycho.2008.05.123
Normal distributions of somal volume estimates in rat hippocampus M. Hosseinisharifabad a, J.R. Nyengaard b Yazd University of Medical Sciences, Department of Anatomy,Yazd, Iran b University of Aarhus, Stereology and Electron Microscopy Research Laboratory, Aarhus, Denmark
a
Introduction: In order to evaluate the specific vulnerability of hippocampal neurons to different aggressive agents, it is important to quantify changes in neuronal size. The precise estimation of individual neuron volume allows one to measure the effect of experimental manipulation. This study, for the first time, aimed to determine normal distributions of unbiased somal volume estimates in rat hippocampal subdivisions. Materials and methods: 2-month-old male Wistar rats were anesthetized with urethan and transcardially perfused with a phosphate-buffered solution of (PH = 7.2, M = 0.12) 4% formaldehyde and 1% glutaraldehyde. Each brain was removed and divided into two hemispheres. One hemisphere was selected at random for estimating number of neurons and the other for estimating individual volume of neurons. The total numbers of dentate granule cells (DG) and pyramidal cells (area CA1–3) in the hippocampus were estimated with the optical fractionator. The Rotator method was applied to estimate the individual volume of neurons. Results: The absolute distribution of unbiased somal volume estimates for hippocampal formation is shown in the figure. Vertical bars represent SEM. Each graph is based on approximately 2500 individual somal volume estimates.
Y.B. Yurov a, I.Y. Iourov a, S.G. Vorsanova b, I.A. Demidova b, A.K. Beresheva b, V.S. Kravets b, V.V. Monakhov a, A.D. Kolotii b, I.V. Soloviev a, V.M. Vostrikov a, N.A. Uranova a, T. Liehr c a National Research Center of Mental Health, RAMS, Laboratory of Cytogenetics, Moscow, Russia b Institute of Pediatrics and Children Surgery, Rosmedtechnologii, Moscow, Russia c Institute of Human Genetics and Anthropology, Jena, Germany The most common form of genetic/genomic instability observed in humans is loss/gain of chromosomes in a cell (aneuploidy). It has been recently suggested that aneuploidy directly affecting brain cells could be a possible genetic mechanism for brain diseases with genetic predisposition (Yurov et al., 2001; Iourov et al., 2006). We tested this hypothesis analyzing the schizophrenia brain using modern molecular cytogenetics techniques that allow high-resolution identification of chromosome numbers and structure at single cell level (based on fluorescence in situ hybridization). We have monitored intercellular chromosome number variations in 18 post-mortem brain samples (prefrontal cortex) of schizophrenia individuals and 18 age- and sex- matched controls. We have found that 4 out of 18 cases demonstrate a stable increase mosaic or low-level aneuploidy. In these samples, the rate of aneuploidy for chromosomes 1 or sex chromosomes X in neuronal and glial cells was in the range 2%–7%, affecting totally from 2 to 7 billions of cells in the diseased cortex. Moreover, stochastic rate of chromosomal mutations in the schizophrenia brain was two-times higher that in the unaffected brain. Together, this suggests that, in at least a number of cases, psychopathophysiology of schizophrenia is mediated by genomic instabilities manifested as aneuploidy. These data highlight such intracellular events in the brain as chromosome variations to be an additional genetic mechanism for schizophrenia pathogenesis. Aneuploidy in humans is usually devastative and hallmarks different types of pathology. In common chromosomal syndromes aneuploidy is usually associated with conspicuous brain malformations. However, small proportions of aneuploid cells do not seem to cause morphologically detectable changes, but seriously affect cellular neurophysiology and neuronal network in a whole. It is noteworthy that a neuron is connected to several thousands of other neurons. Therefore, if a neuron has a loss/gain of several thousands genes of a chromosome involved in aneuploidy, it will negatively affects the functions of other neurons as well neuron-glia interaction. This suggests that even peculiar proportion of aneuploid neurons has impressive psychophysiological impact. Finally, further investigations are needed in order to define the incidence of brain specific aneuploidy in schizophrenia as well as more precise definition of aneuploidy impact on physiology of brain cells.
doi:10.1016/j.ijpsycho.2008.05.583