Oliver von Bohlen und Halbach | Universität Greifswald (original) (raw)

Papers by Oliver von Bohlen und Halbach

Biotechnic & Histochemistry, 1999

3,3'-Diaminobenzidine (DAB) is widely used as a chromogen for visualization of horseradis... more 3,3'-Diaminobenzidine (DAB) is widely used as a chromogen for visualization of horseradish peroxidase activity in neuroanatomical tracing experiments and in immunohistochemistry. The product of the enzymatically catalyzed oxidation of DAB by hydrogen peroxide is brown and nonfluorescent. In frozen sections of formaldehyde fixed rat and mouse brain that had been exposed to DAB either alone or with hydrogen peroxide, we observed strong greenish fluorescence in myelinated nerve fibers and in the somata of some neurons. This fluorescence was not associated with brown coloration and was not due to endogenous peroxidase activity. Extractions, blocking reactions, and other histochemical tests indicate that the fluorescence resulted from the combination of DAB with aldehyde groups that were formed by oxidation of unsaturated linkages in lipids. DAB induced fluorescence provides a simple and useful demonstration of background anatomy in sections that also contain specifically localized deposits of peroxidase activity.

Journal of Neurochemistry, 2010

Repeated exposure to opiates leads to cellular and molecular changes and behavioral alterations r... more Repeated exposure to opiates leads to cellular and molecular changes and behavioral alterations reflecting a state of dependence. In noradrenergic neurons, cyclic AMP (cAMP)dependent pathways are activated during opiate withdrawal, but their contribution to the activity of locus coeruleus noradrenergic neurons and behavioral manifestations remains controversial. Here, we test whether the cAMP-dependent transcription factors cAMP responsive element binding protein (CREB) and cAMP-responsive element modulator (CREM) in noradrenergic neurons control the cellular markers and the physical signs of morphine withdrawal in mice. Using the Cre/ loxP system we ablated the Creb1 gene in noradrenergic neurons. To avoid adaptive effects because of compensatory up-regulation of CREM, we crossed the conditional Creb1 mutant mice with a Crem)/) line. We found that the enhanced expression of tyrosine hydroxylase normally observed during withdrawal was attenuated in CREB/CREM mutants. Moreover, the withdrawal-associated cellular hyperactivity and cfos expression was blunted. In contrast, naloxone-precipitated withdrawal signs, such as jumping, paw tremor, tremor and mastication were preserved. We conclude by a specific genetic approach that the withdrawal-associated hyperexcitability of noradrenergic neurons depends on CREB/CREM activity in these neurons, but does not mediate several behavioral signs of morphine withdrawal.

Biological Psychiatry, 2006

Changes in densities and in the morphology of dendritic spines in the hippocampus are linked to h... more Changes in densities and in the morphology of dendritic spines in the hippocampus are linked to hippocampal long-term potentiation (LTP), spatial learning, and depression. Decreased brain-derived neurotrophic factor (BDNF) levels seem to contribute to depression. Through its receptor trkB, BDNF is also involved in hippocampal LTP and hippocampus-dependent learning. Conditionally gene-targeted mice in which the ablation of trkB is restricted to the forebrain and occurs only during postnatal development display impaired learning and LTP. To examine whether there is a link among impaired hippocampal synaptic plasticity, altered spines, and trkB receptors, we performed a quantitative analysis of spine densities and spine length in the hippocampal area CA1 and the dentate gyrus in conditional mutant mice (trkB(lox/lox)CaMKII-CRE mice). TrkB protein and mRNA levels were assayed using Western blot and in situ hybridization analysis. Fifteen-week-old mutant mice exhibit specific reductions in spine densities and a significant increase in spine length of apical and basal dendrites in area CA1. These alterations correlate with a time- and region-specific reduction in full-length trkB mRNA in the hippocampus. TrkB functions in structural remodeling of hippocampal dendritic spines, which in turn may affect synaptic transmission and plasticity.

Cell and Tissue Research, 2004

Cell and Tissue Research, 2007

The transient receptor potential (TRP) superfamily comprises of a group of non-selective cation c... more The transient receptor potential (TRP) superfamily comprises of a group of non-selective cation channels that have been implicated in both receptor and store-operated channel functions. The family of classical TRPs (TRPCs) consists of seven members (TRPC1-7), with TRPC4 possibly playing a role in neuronal signaling. We have examined the distribution pattern of TRPC4 mRNA and protein in the developing and postnatal murine brain by using in situ hybridization, Western blotting, and immunocytochemistry. Expression of TRPC4 mRNA starts at embryonic day 14.5 (E14.5) in the developing septal area and cerebellar anlagen. At E16.5, prominent expression is additionally seen in the hippocampal formation and cortical plate. High densities of cells expressing TRPC4 mRNA occur in the adult olfactory bulb and hippocampus, whereas the cortex and septum display lower densities of cells positive for TRPC4 mRNA. Analysis of the adult hippocampal formation has revealed TRPC4 immunoreactivity in hippocampal areas CA1 to CA3 and in the dentate gyrus. Functions consistent with this spatially restricted pattern of expression remain to be revealed.

International Journal of Developmental Neuroscience, 2010

The LRRK2 gene was recently found to have multiple mutations that are causative for the most comm... more The LRRK2 gene was recently found to have multiple mutations that are causative for the most common inherited form of late onset Parkinson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s disease. In the adult brain, LRRK2 mRNA is broadly expressed, also in regions other than the nigrostriatal system. In order to establish a basis for assessing more detailed functional implications of LRRK2 in development, we provide here an in-depth analysis of its mRNA expression patterns in neural and extra-neural tissues with a focus on murine embryonic development. LRRK2 mRNA is detectable at E8.5 in non-neural and at E10.5 in neural tissues. From E12.5 to E16.5, LRRK2 mRNA is prominently expressed throughout the neocortex and subsequently highly concentrated in ventricular and subventricular zones and cortical plate. In addition, developing cerebellar granule and Purkinje neurons and spinal cord neurons display robust LRRK2 expression. In non-neural tissues LRRK2 was highly expressed in limb interdigital zones, developing kidney glomeruli, and spermatogenetic cells. Together, our results suggest roles for LRRK2 in controlling proliferation, migration, and differentiation of neural cells as well as in morphogenesis of extra-neural tissues.

It is known since a long time that the hippocampus is sensitive to aging. Thus, there is a reduct... more It is known since a long time that the hippocampus is sensitive to aging. Thus, there is a reduction in the hippocampal volume during aging. This age-related volume reduction is paralleled by behavioral and functional deficits in hippocampus-dependent learning and memory tasks. This age-related volume reduction of the hippocampus is not a consequence of an age-related loss of hippocampal neurons. The morphological changes associated with aging include reductions in the branching pattern of dendrites, as well as reductions in spine densities, reductions in the densities of fibers projecting into the hippocampus as well as declines in the rate of neurogenesis. It is very unlikely that a single factor or a single class of molecules is responsible for all these age-related morphological changes in the hippocampus. Nevertheless, it would be of advantage to identify possible neuromodulators or neuropeptides that may contribute to these age-related changes. In this context, growth factors may play an important role in the maintenance of the postnatal hippocampal architecture. In this review it is hypothesized that brain-derived neurotrophic factor (BDNF) is a factor critically involved in the regulation of age-related processes in the hippocampus. Moreover, evidences suggest that disturbances in the BDNF-system also affect hippocampal dysfunctions, as e.g. seen in major depression or in Alzheimer disease.

Regulatory Peptides, 2001

Angiotensin II (Ang II) is a potent vasoactive peptide and displays growth factor-like properties... more Angiotensin II (Ang II) is a potent vasoactive peptide and displays growth factor-like properties. Different high-affinity Ang II receptor subtypes (AT1A, AT1B and AT2) have been cloned. They are expressed in various brain structures. Additionally, it has been assumed that Mas could interact directly or indirectly with the renin-angiotensin system. The AT1 receptor mediates pressor and mitogenic effects of Ang II, whereas physiological function and signaling mechanisms of the AT2 receptor remain poorly understood. Recent reports have shown that Ang II could mediate apoptosis through AT2 receptors. Since the AT1A, AT2 and Mas knockout mice provide new tools for uncovering potential actions of Ang II, the cell number in different brain structures of male adult wild-type mice and mice deficient for AT1A, AT2 or Mas was evaluated to get more insight into the role of Ang II in central nervous system development. In nearly all investigated brain structures (cortex, hippocampus, amygdala, thalamus), the cell number was significantly higher in AT2-deficient mice in comparison to wild-type mice. To the contrary, in AT1A-deficient mice the cell number was significantly less than in controls in the lateral geniculate and the medial amygdaloid nucleus. However, cell numbers were not changed in Mas-knockout mice compared to their wild-types. These results show the contrary effects of both angiotensin receptors on cell growth and represent the first demonstration of their action on neuronal cell development evidenced in the adult mouse brain.

PLoS ONE, 2011

The transient receptor potential vanilloid type 1 (TRPV1) channel is a well recognized polymodal ... more The transient receptor potential vanilloid type 1 (TRPV1) channel is a well recognized polymodal signal detector that is activated by painful stimuli such as capsaicin. Here, we show that TRPV1 is expressed in the lateral nucleus of the amygdala (LA). Despite the fact that the central amygdala displays the highest neuronal density, the highest density of TRPV1 labeled neurons was found within the nuclei of the basolateral complex of the amygdala. Capsaicin specifically changed the magnitude of long-term potentiation (LTP) in the LA in brain slices of mice depending on the anesthetic (ether, isoflurane) used before euthanasia. After ether anesthesia, capsaicin had a suppressive effect on LA-LTP both in patch clamp and in extracellular recordings. The capsaicin-induced reduction of LTP was completely blocked by the nitric oxide synthase (NOS) inhibitor L-NAME and was absent in neuronal NOS as well as in TRPV1 deficient mice. The specific antagonist of cannabinoid receptor type 1 (CB1), AM 251, was also able to reduce the inhibitory effect of capsaicin on LA-LTP, suggesting that stimulation of TRPV1 provokes the generation of anandamide in the brain which seems to inhibit NO synthesis. After isoflurane anesthesia before euthanasia capsaicin caused a TRPV1-mediated increase in the magnitude of LA-LTP. Therefore, our results also indicate that the appropriate choice of the anesthetics used is an important consideration when brain plasticity and the action of endovanilloids will be evaluated. In summary, our results demonstrate that TRPV1 may be involved in the amygdala control of learning mechanisms.

Nitric Oxide, 2003

Nitric oxide (NO) is a major modulator of neural functions. Since NO is a gaseous molecule with v... more Nitric oxide (NO) is a major modulator of neural functions. Since NO is a gaseous molecule with very short half-life, the spatial distribution of NO and its relationship to neuronal activity are difficult to resolve. Non-invasive and direct visualization of NO in neuronal tissues had been hampered by the lack of a suitable method to identify NO directly. A fluorescent indicator, which directly detects NO under physiological conditions, would be advantageous. Several indicators for direct detection of NO have been developed, which react with NO by forming a fluorescent complex. However, some of these dyes have cytotoxic properties or have been found to be rather unspecific under certain conditions. Fortunately, some of the indicators, which change their fluorescent pattern in the presence of NO, appear to be promising for the visualization of NO. Since little is known about the spatial spread and the temporal aspects of NO release after a specific stimulus, the use of the specific and non-toxic fluorescent NO indicators could provide a potentially powerful tool to study these aspects of NO release in neuronal tissues in vitro and in vivo. Such measurements, especially in combination with electrophysiological recordings, would greatly further NO research. In addition, based on their fluorescent pattern, these NO-sensitive dyes can be distinguished from the calcium-sensitive dye Fura-2, which allows NO-imaging together with calcium-imaging. This article summarizes recent advances and current trends in the visualization of NO in living neuronal tissues.

Journal of Neuroscience Methods, 1998

In preparation for electrophysiological studies, the fiber pathways within the amygdala of rats h... more In preparation for electrophysiological studies, the fiber pathways within the amygdala of rats have been examined using a combined Nissl- and silver-staining method (Bielshowsky) in horizontal sections of the amygdala. To determine if fibers in the lateral nucleus of the amygdala are in functional connection with other brain regions, an anterograde and retrograde axonal tracing method (application of rhodamine-dextran-amine) was performed. Horizontal slices containing some nuclei of the amygdala (lateral nucleus, basolateral nucleus, central nucleus, medial nucleus), as well as the entorhinal cortex, the hippocampus and parts of the piriform cortex were used. Crystals of rhodamine-dextran-amine were placed in the lateral nucleus. Intra-amygdaloid connections as well as connections to other brain regions were preserved in this preparation. The connectivities of the lateral nucleus with other nuclei of the amygdala (basolateral, medial, central) correspond with the findings made by tracer applications in-vivo. The use of a tracer that is transported in both the antero- and retrograde direction shows the whole spectrum of efferent and afferent fibers which are involved in the projection pattern of the lateral nucleus. To test the usefulness of this preparation for electrophysiological studies, extracellular field potentials were recorded.

Journal of Molecular Medicine, 2008

Mental retardation is the most frequent cause of serious handicap in children and young adults. M... more Mental retardation is the most frequent cause of serious handicap in children and young adults. Mutations in the human angiotensin II type 2 receptor (AT2) have been implicated in X-linked forms of mental retardation. We here demonstrate that mice lacking the AT2 receptor gene are significantly impaired in their performance in a spatial memory task and in a one-way active avoidance task. As no difference was observed between the genotypes in fear conditioning, the detected deficit in spatial memory may not relate to fear. Notably, receptor knockout mice showed increased motility in an activity meter and elevated plus maze. Importantly, these mice are characterized by abnormal dendritic spine morphology and length, both features also found to be associated with some cases of mental Hull, UK). He is especially interested in peptide systems and their role in the aetiology of different diseases, mainly focussing on cardiovascular pathophysiology in end-organs like brain, kidneys or heart. retardation. These findings suggest a crucial role of AT2 in normal brain function and that dysfunction of the receptor has impact on brain development and ultrastructural morphology with distinct consequences on learning and memory.

Brain Research Bulletin, 1998

In this study the effects of angiotensin II and norleucine1-angiotensin IV have been studied in a... more In this study the effects of angiotensin II and norleucine1-angiotensin IV have been studied in a horizontal in vitro slice preparation of female rat brains. Extracellular field potentials of the lateral nucleus of the basolateral amygdala were recorded. The results show that angiotensin II significantly increased the amplitude of field potentials induced by the electrical stimulation of the lateral nucleus, whereas norleucine1-angiotensin IV caused a significant decrease in the amplitude of field potentials. The angiotensin-induced effects could be blocked by specific angiotensin receptor antagonists. These opposite effects of angiotensin II and IV on electrophysiological parameters are in agreement with behavioral studies that have demonstrated that angiotensin II and IV produce opposite effects on the retention of an inhibitory shock-avoidance response and correlate with their different effects on the blood vessels.

Annals of the New York Academy of Sciences, 2006

Annals of Anatomy - Anatomischer Anzeiger, 2009

Most excitatory input in the hippocampus impinges on dendritic spines. Therefore, the dendritic s... more Most excitatory input in the hippocampus impinges on dendritic spines. Therefore, the dendritic spines are likely to be of major importance for neural processing. The morphology of dendritic spines is very diverse and changes in spine size as well as in their density are thought to reflect changes in the strength of synaptic transmission. Thus, alterations in dendritic spine densities or shape are suspected to be morphological manifestations of psychopathological, pathophysiological, physiological and/or behavioural changes. However, in spite of a long history of research, the specific function of dendritic spines within the hippocampal formation is still not well understood. This review will shed light on the hippocampal dendritic spines, their ultrastructure and morphology, as well as their supposed roles in neuronal plasticity and in certain mental illnesses.

Neural Development, 2007

Background: Extracellular signaling through receptors for neurotrophins mediates diverse neuronal... more Background: Extracellular signaling through receptors for neurotrophins mediates diverse neuronal functions, including survival, migration and differentiation in the central nervous system, but the transcriptional targets and regulators that mediate these diverse neurotrophin functions are not well understood.

Journal of Neuroscience, 2009

Understanding the modulation of the neural circuitry of fear is clearly one of the most important... more Understanding the modulation of the neural circuitry of fear is clearly one of the most important aims in neurobiology. Protein phosphorylation in response to external stimuli is considered a major mechanism underlying dynamic changes in neural circuitry. TrkB (Ntrk2) neurotrophin receptor tyrosine kinase potently modulates synaptic plasticity and activates signal transduction pathways mainly through two phosphorylation sites [Y515/Shc site; Y816/PLC␥ (phospholipase C␥) site]. To identify the molecular pathways required for fear learning and amygdalar synaptic plasticity downstream of TrkB, we used highly defined genetic mouse models carrying single point mutations at one of these two sites (Y515F or Y816F) to examine the physiological relevance of pathways activated through these sites for pavlovian fear conditioning (FC), as well as for synaptic plasticity as measured by field recordings obtained from neurons of different amygdala nuclei. We show that a Y816F point mutation impairs acquisition of FC, amygdalar synaptic plasticity, and CaMKII signaling at synapses. In contrast, a Y515F point mutation affects consolidation but not acquisition of FC to tone, and also alters AKT signaling. Thus, TrkB receptors modulate specific phases of fear learning and amygdalar synaptic plasticity through two main phosphorylation docking sites.

Hippocampus, 2004

Kindling is characterized by a progressive intensification of seizure activity culminating in gen... more Kindling is characterized by a progressive intensification of seizure activity culminating in generalized seizures following repeated administration of an initially subconvulsive electrical or chemical stimulus. Since it is known that epilepsy induces morphological alterations in the limbic system, we examined the neuropathological consequences of kindling with a sensitive silver-staining method for the visualization of damaged neurons and Nissl staining for the estimation of the neuronal densities in different limbic areas. Wistar rats implanted with electrodes in the left basolateral nucleus were stimulated until 15 consecutive stage V seizures (scale of Racine). Amygdala-kindled animals had reduced cell density in the amygdala and increased density of fragments of degenerated axons. Reduced neuronal density and the occurrence of degenerated axons in kindled animals were more prominent in the ipsilateral than in the contralateral hemisphere. In addition, more degenerated axons were found in cortical structures of kindled than sham-operated animals. These results indicate that kindling induced morphological alterations that were not restricted to either the ipsilateral hemisphere or the stimulated region. These morphological changes might be responsible for the emotional and behavioral disturbances that can accompany epilepsy.

The FASEB Journal, 2005

The neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) have been sh... more The neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) have been shown to promote survival and differentiation of midbrain dopaminergic (DAergic) neurons in vitro and in vivo. This is consistent with their expression and that of their cognate receptors, trkB and trkC, in the nigrostriatal system. Degeneration of DAergic neurons of the substantia nigra and α-synuclein-positive aggregates in the remaining substantia nigra (SN) neurons are hallmarks of Parkinson's disease (PD). Reduced expression of BDNF has been reported in the SN from PD patients. Moreover, mutations in the BDNF gene have been found to play a role in the development of familial PD. We show now that haploinsufficiencies of the neurotrophin receptors trkB and/or trkC cause a reduction in numbers of SN neurons in aged (21-23 month old) mice, which is accompanied by a reduced density in striatal tyrosine hydroxylase immunoreactive (TH-ir) fibers. These aged mutant mice, in contrast to wild-type littermates, display an accumulation of α-synuclein in the remaining TH-positive neurons of the SN. We conclude that impairment in trkB and/or trkC signaling induces a phenotype in the aged SN, which includes two hallmarks of PD, losses of TH positive neurons and axons along with massive neuronal deposits of α-synuclein.

The EMBO Journal, 2004

The generation of complex neuronal structures, such as the neocortex, requires accurate positioni... more The generation of complex neuronal structures, such as the neocortex, requires accurate positioning of neurons and glia within the structure, followed by differentiation, formation of neuronal connections, and myelination. To understand the importance of TrkB signaling during these events, we have used conditional and knockin mutagenesis of the TrkB neurotrophin receptor, and we now show that this tyrosine kinase receptor, through docking sites for the Shc/FRS2 adaptors and phospholipase Cgamma (PLCgamma), coordinates these events in the cerebral cortex by (1) controlling cortical stratification through the timing of neuronal migration during cortex formation, and (2) regulating both neuronal and oligodendrocyte differentiation. These results provide genetic evidence that TrkB regulates important functions throughout the formation of the cerebral cortex via recruitment of the Shc/FRS2 adaptors and PLCgamma.