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278 results on '"Hörtnagl, Heide"'

8. Fear Memory Retrieval Is Associated With a Reduction in AMPA Receptor Density at Thalamic to Amygdala Intercalated Cell Synapses

Author

Seewald, Anna, Schönherr, Sabine, Hörtnagl, Heide, Ehrlich, Ingrid, Schmuckermair, Claudia, and Ferraguti, Francesco

Subjects
memory, Cellular and Molecular Neuroscience, nervous system, glutamate receptor, plasticity, medial geniculate nucleus, Cell Biology, freeze-fracture, fear conditioning, Neuroscience, Original Research
Abstract

The amygdala plays a crucial role in attaching emotional significance to environmental cues. Its intercalated cell masses (ITC) are tight clusters of GABAergic neurons, which are distributed around the basolateral amygdala complex. Distinct ITC clusters are involved in the acquisition and extinction of conditioned fear responses. Previously, we have shown that fear memory retrieval reduces the AMPA/NMDA ratio at thalamic afferents to ITC neurons within the dorsal medio-paracapsular cluster. Here, we investigate the molecular mechanisms underlying the fear-mediated reduction in the AMPA/NMDA ratio at these synapses and, in particular, whether specific changes in the synaptic density of AMPA receptors underlie the observed change. To this aim, we used a detergent-digested freeze-fracture replica immunolabeling technique (FRIL) approach that enables to visualize the spatial distribution of intrasynaptic AMPA receptors at high resolution. AMPA receptors were detected using an antibody raised against an epitope common to all AMPA subunits. To visualize thalamic inputs, we virally transduced the posterior thalamic complex with Channelrhodopsin 2-YFP, which is anterogradely transported along axons. Using face-matched replica, we confirmed that the postsynaptic elements were ITC neurons due to their prominent expression of μ-opioid receptors. With this approach, we show that, following auditory fear conditioning in mice, the formation and retrieval of fear memory is linked to a significant reduction in the density of AMPA receptors, particularly at spine synapses formed by inputs of the posterior intralaminar thalamic and medial geniculate nuclei onto identified ITC neurons. Our study is one of the few that has directly linked the regulation of AMPA receptor trafficking to memory processes in identified neuronal networks, by showing that fear-memory induced reduction in AMPA/NMDA ratio at thalamic-ITC synapses is associated with a reduced postsynaptic AMPA receptor density.

Published
2021
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34. Distinct gradients of various neurotransmitter markers in caudate nucleus and putamen of the human brain.

Author

Hörtnagl, Heide, Pifl, Christian, Hörtnagl, Erik, Reiner, Angelika, and Sperk, Günther

Subjects
*CAUDATE nucleus, *NEUROTRANSMITTERS, *SEROTONIN, *PARKINSON'S disease, *HOMOVANILLIC acid, *BRAIN, *NEUROLOGICAL disorders, *DUCTUS arteriosus
Abstract

The caudate nucleus (CN) and the putamen (PUT) as parts of the human striatum are distinguished by a marked heterogeneity in functional, anatomical, and neurochemical patterns. Our study aimed to document in detail the regional diversity in the distribution of dopamine (DA), serotonin, γ‐aminobuturic acid, and choline acetyltransferase within the CN and PUT. For this purpose we dissected the CN as well as the PUT of 12 post‐mortem brains of human subjects with no evidence of neurological and psychiatric disorders (38–81 years old) into about 80 tissue parts. We then investigated rostro‐caudal, dorso‐ventral, and medio‐lateral gradients of these neurotransmitter markers. All parameters revealed higher levels, turnover rates, or activities in the PUT than in the CN. Within the PUT, DA levels increased continuously from rostral to caudal. In contrast, the lowest molar ratio of homovanillic acid to DA, a marker of DA turnover, coincided with highest DA levels in the caudal PUT, the part of the striatum with the highest loss of DA in Parkinson's disease (N. Engl. J. Med., 318, 1988, 876). Highest DA concentrations were found in the most central areas both in the PUT and CN. We observed an age‐dependent loss of DA in the PUT and CN that did not correspond to the loss described for Parkinson's disease indicating different mechanisms inducing the deficit of DA. Our data demonstrate a marked heterogeneity in the anatomical distribution of neurotransmitter markers in the human dorsal striatum indicating anatomical and functional diversity within this brain structure. [ABSTRACT FROM AUTHOR]

Published
2020
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38. Phosphoinositide-Dependent Protein Kinase 1 (PDK1)

Author

Lang, Undine E, Ackermann, Teresa F, Wolfer, David, Schubert, Florian, Sohr, Reinhard, Hörtnagl, Heide, Lang, Florian, Gallinat, Juergen, University of Zurich, and Lang, Undine E

Subjects
10017 Institute of Anatomy, phenotype, 1201 Arts and Humanities (miscellaneous), Schizophrenia, 570 Life sciences, biology, 610 Medicine & health, 3200 General Psychology, psychosis
Published
2015

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