Rosalinda C Roberts

University of Alabama at Birmingham, Birmingham, Alabama, United States

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Publications (120)368.35 Total impact

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    ABSTRACT: Previous work from our laboratory showed deficits in tyrosine hydroxylase protein expression within the substantia nigra/ventral tegmental area (SN/VTA) in schizophrenia. However, little is known about the nature and specific location of these deficits within the SN/VTA. The present study had two aims: (1) test if tyrosine hydroxylase deficits could be explained as the result of neuronal loss; (2) assess if deficits in tyrosine hydroxylase are sub-region specific within the SN/VTA, and thus, could affect specific dopaminergic pathways. To achieve these objectives: (1) we obtained estimates of the number of dopaminergic neurons, total number of neurons, and their ratio in matched SN/VTA schizophrenia and control samples; (2) we performed a qualitative assessment in SN/VTA schizophrenia and control matched samples that were processed simultaneously for tyrosine hydroxylase immunohistochemistry. We did not find any significant differences in the total number of neurons, dopaminergic neurons, or their ratio. Our qualitative study of TH expression showed a conspicuous decrease in labeling of neuronal processes and cell bodies within the SN/VTA, which was sub-region specific. Dorsal diencephalic dopaminergic populations of the SN/VTA presented the most conspicuous decrease in TH labeling. These data support the existence of pathway-specific dopaminergic deficits that would affect the dopamine input to the cortex without significant neuronal loss. Interestingly, these findings support earlier reports of decreases in tyrosine hydroxylase labeling in the target areas for this dopaminergic input in the prefrontal and entorhinal cortex. Finally, our findings support that tyrosine hydroxylase deficits could contribute to the hypodopaminergic state observed in cortical areas in schizophrenia. PMID: 25269834
    Brain Structure and Function 10/2014; [Epub ahead of print]. · 7.84 Impact Factor
  • Rosalinda C Roberts, Joy K Roche, Robert E McCullumsmith
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    ABSTRACT: The process of glutamate release, activity, and reuptake involves the astrocyte, the presynaptic and postsynaptic neuron. Glutamate is released into the synapse and may occupy and activate receptors on both neurons and astrocytes. Glutamate is rapidly removed from the synapse by a family of plasma membrane excitatory amino acid transporters (EAATs), also localized to neurons and astrocytes. The purpose of the present study was to examine EAAT labeling in postmortem human cortex at the light and electron microscopic levels. Postmortem prefrontal cortex was processed for EAAT1 and EAAT2 immunohistochemistry. At the light microscopic level, EAAT1 and EAAT2 labeling was found in both grey and white matter. Most cellular labeling was in small cells which were morphologically similar to glia. In addition, EAAT1 labeled neurons were scattered throughout, some of which were pyramidal in shape. At the electron microscopic level, EAAT1 and EAAT2 labeling was found in astrocytic soma and processes surrounding capillaries. EAAT labeling was also found in small astocytic processes adjacent to axon terminals forming asymmetric (glutamatergic) synapses. While EAAT2 labeling was most prevalent in astrocytic processes, EAAT1 labeling was also present in neuronal processes including the soma, axons, and dendritic spines. Expression of EAAT1 protein on neurons may be due to the hypoxia associated with the postmortem interval, and requires further confirmation. The localization of EAATs on the astrocytic plasma membrane and adjacent to excitatory synapses is consistent with the function of facilitating glutamate reuptake and limiting glutamate spillover. Establishment that EAAT1 and EAAT2 can be measured at the EM level in human postmortem tissues will permit testing of hypotheses related to these molecules in diseases lacking analogous animal models.
    Neuroscience 07/2014; · 3.12 Impact Factor
  • Lesley A McCollum, Rosalinda C Roberts
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    ABSTRACT: Many behavioral, physiological, and anatomical studies utilize animal models to investigate human striatal pathologies. Although commonly used, rodent striatum may not present the optimal animal model for certain studies due to a lesser morphological complexity than that of non-human primates, which are increasingly restricted in research. As an alternative, the tree shrew could provide a beneficial animal model for studies of the striatum. The gross morphology of the tree shrew striatum resembles that of primates, with separation of the caudate and putamen by the internal capsule. The neurochemical anatomy of the ventral striatum, specifically the nucleus accumbens, has never been examined. This major region of the limbic system plays a role in normal physiological functioning and is also an area of interest for human striatal disorders. The current study uses immunohistochemistry of calbindin and tyrosine hydroxylase (TH) to determine the ultrastructural organization of the nucleus accumbens core and shell of the tree shrew (Tupaia glis belangeri). Stereology was used to quantify the ultrastructural localization of TH, which displays weaker immunoreactivity in the core and denser immunoreactivity in the shell. In both regions, synapses with TH-immunoreactive axon terminals were primarily symmetric and showed no preference for targeting dendrites versus dendritic spines. The results were compared to previous ultrastructural studies of TH and dopamine in rat and monkey nucleus accumbens. Tree shrew and monkey show no preference for the postsynaptic target in the shell, in contrast to rats which show a preference for synapsing with dendrites. Tree shrews have a ratio of asymmetric to symmetric synapses formed by TH-immunoreactive terminals that is intermediate between rats and monkey. The findings from this study support the tree shrew as an alternative model for studies of human striatal pathologies.
    Neuroscience 04/2014; · 3.12 Impact Factor
  • K A Barksdale, A C Lahti, Rosalinda C Roberts
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    ABSTRACT: The anterior cingulate cortex (ACC) is one of several brain regions that are abnormal in schizophrenia (SZ). Here we compared markers of synapse and mitochondrial function using Western blots of postmortem ACC in: 1) normal controls (NCs, n=13) vs. subjects with SZ (n=25); NC, treatment resistant SZ and treatment responsive SZ; and 3) NC, SZ treated with typical or atypical antipsychotic drugs (APDs). Protein levels of synaptophysin, mitofusin2, vGLUT1 and calcineurin did not differ between the NC and SZ group as a whole, or the NCs vs. the SZ group divided by treatment response or type of APD. In several cases the levels of vGLUT1 were minuscule or absent. The proportion of NCs lacking vGLUT1 was significantly less than that of the SZ groups. There were several positive correlations across all subjects between: 1) synaptophysin and vGLUT1, 2) synaptophysin and calcineurin, 3) synaptophysin and mitofusin and 4) calcineurin and mitofusin. Synaptophysin and calcineurin were positively correlated in responders, and this correlation was significantly stronger than in treatment resistant SZs or NCs. Synaptophysin and calcineurin were positively correlated in SZ on atypical APD; this correlation was significantly stronger than SZ on typical APD or NC. Mitofusin2 and calcineurin were positively correlated in SZ on atypical APD and NC; this correlation was stronger in SZ on atypical rather than typical APD or NCs. The correlation between these proteins, which have roles in synaptic vesicle cycling, glutamate transmission, mitochondrial fusion and calcium buffering, is complex and was differentially regulated among the groups.Neuropsychopharmacology accepted article preview online, 7 March 2014; doi:10.1038/npp.2014.57.
    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 03/2014; · 8.68 Impact Factor
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    ABSTRACT: Perturbations in metabolism are a well-documented but complex facet of schizophrenia pathology. Optimal cellular performance requires the proper functioning of the electron transport chain, which is constituted by four enzymes located within the inner membrane of mitochondria. These enzymes create a proton gradient that is used to power the enzyme ATP synthase, producing ATP, which is crucial for the maintenance of cellular functioning. Anomalies in a single enzyme of the electron transport chain are sufficient to cause disruption of cellular metabolism. The last of these complexes is the cytochrome c oxidase (COX) enzyme, which is composed of thirteen different subunits. COX is a major site for oxidative phosphorylation, and anomalies in this enzyme are one of the most frequent causes of mitochondrial pathology. The objective of the present report was to assess if metabolic anomalies linked to COX dysfunction may contribute to substantia nigra/ventral tegmental area (SN/VTA) pathology in schizophrenia. We tested COX activity in postmortem SN/VTA from schizophrenia and non-psychiatric controls. We also tested the protein expression of key subunits for the assembly and activity of the enzyme, and the effect of antipsychotic medication on subunit expression. COX activity was not significantly different between schizophrenia and non-psychiatric controls. However, we found significant decreases in the expression of subunits II and IV-I of COX in schizophrenia. Interestingly, these decreases were observed in samples containing the entire rostro-caudal extent of the SN/VTA, while no significant differences were observed for samples containing only mid-caudal regions of the SN/VTA. Finally, rats chronically treated with antipsychotic drugs did not show significant changes in COX subunit expression. These findings suggest that COX subunit expression may be compromised in specific sub-regions of the SN/VTA (i.e. rostral regions), which may lead to a faulty assembly of the enzyme and a greater vulnerability to metabolic insult.
    PLoS ONE 01/2014; 9(6):e100054. · 3.53 Impact Factor
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    ABSTRACT: Glycogen synthase kinase-3β (GSK3β) activity has been previously linked to Alzheimer's disease (AD) by its phosphorylation of tau and activation by amyloid. GSK3β intracellular distribution is important in regulating its activity by restricting access to compartment-specific substrates. This study investigated regional and intracellular distribution of GSK3β in a mouse model of AD, a bigenic mouse with combined amyloid and tau pathology (BiAT), and controls (FVB). At two different ages, the entire rostrocaudal extent of each brain was examined. Young (six months old) FVB and BiAT mice did not differ in GSK3β expression and localization. In old (13 months old) BiAT mice, neurons showed increased GSK3β expression only in AD-relevant brain regions as compared to modest staining in region- and age-matched controls. Two regions with the most robust changes between FVB and BiAT mice, the amygdala and piriform cortex, were quantified at the light microscopic level. In both regions, the density of darkly labeled neurons was significantly greater in the old BiAT mice vs. the old FVB mice. Electron microscopy of the piriform cortex showed neuronal GSK3β labeling in the rough endoplasmic reticulum, on ribosomes, and on microtubules in dendrites in both strains of mice. In old BiAT mice, GSK3β labeling was qualitatively more robust compared to age-matched controls, and GSK3β also appeared in neurofibrillary tangles. In conclusion, GSK3β expression was increased in specific intracellular locations and was found in tangles in old BiAT mice, suggesting that GSK3β overexpression in specific brain areas may be intrinsic to AD pathology. Synapse, 2013. © 2013 Wiley Periodicals, Inc.
    Synapse 02/2013; · 2.31 Impact Factor
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    ABSTRACT: Cytochrome oxidase (COX) is the enzyme that constitutes the last step of the mitochondrial electron transport chain for the production of ATP. Measurement of COX activity can be achieved by histochemistry, thus providing information about the metabolic status of the brain. Brain regions with high metabolism will present high COX activity in histochemistry assays and vice versa. Using histochemistry versus biochemistry to assess COX activity presents the advantage of providing a map of the differences in metabolism in discrete brain regions. Moreover, COX histochemistry allows quantifying the activity of a particular brain region, by converting units of optical density into units of activity. In the present work we have devised a methodology that allows not only quantifying differences in COX activity between groups, but also quantifying the amount of COX present in brain tissue sections, by directly relating optical density (OD) measurements to cytochrome C oxidase concentration, something that traditionally is achieved by the use of western blot. For this purpose we created a set of standards of known concentration of COX that were affixed to a nitrocellulose membrane, and this membrane was incubated together with the tissue sections in which COX activity was assessed. A standard curve was created using a gradient of different concentrations of purified bovine heart cytochrome oxidase (from 2 micrograms to 0.1 micrograms in intervals of 0.25 micrograms). This standard curve allowed us to detect changes in optical density as low as 5%, and relate these OD differences with known concentrations of cytochrome C oxidase.
    Journal of neuroscience methods 01/2013; · 2.30 Impact Factor
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    Dataset: Brak2502XKB
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Publication Stats

2k Citations
368.35 Total Impact Points

Institutions

  • 2008–2014
    • University of Alabama at Birmingham
      • Department of Psychiatry and Behavioral Neurobiology
      Birmingham, Alabama, United States
  • 2005–2011
    • University of Maryland, Baltimore County
      Baltimore, Maryland, United States
  • 1993–2011
    • University of Maryland, Baltimore
      • Department of Psychiatry
      Baltimore, MD, United States
  • 2010
    • University of Alabama
      Tuscaloosa, Alabama, United States
  • 2002–2010
    • University of Illinois at Chicago
      • Department of Psychiatry (Chicago)
      Chicago, IL, United States
  • 2009
    • University of Cincinnati
      • Department of Psychiatry
      Cincinnati, OH, United States
  • 2007
    • University of Texas Southwestern Medical Center
      • Department of Psychiatry
      Dallas, TX, United States
  • 1996–2007
    • University of Maryland Medical Center
      • Department of Psychiatry
      Baltimore, Maryland, United States
  • 2004
    • Loyola University Maryland
      Baltimore, Maryland, United States