Ipsilateral and contralateral hippocampal CA3–CA1 and CA2–CA1 projections were investigated in adult male Long–Evans rats by retrograde tracing. Injection of the retrograde tracer cholera toxin ...subunit B in the strata oriens and radiatum of dorsal CA1 resulted in labeling of predominantly pyramidal cells in ipsilateral and contralateral CA3 and CA2. The contralateral and ipsilateral anterior–posterior extents of CA3 innervation to CA1 were similar. Fifteen to twenty per cent of the hippocampus proper cells that give rise to CA1 stratum oriens innervation were CA2 pyramidal cells, whereas CA2 cells were a mere 3% for CA1 stratum radiatum innervation. The preferred projection of CA2 pyramidal cells to the CA1 stratum oriens was also manifested in transgenic mice that express GFP under the control of the CACNG5 promoter, in which CA2 cells express high amounts of GFP. The ratios of ipsilateral to contralateral projections were compared. For the CA3–CA1 connection, we found that dorsal CA1 stratum radiatum received more ipsilateral projections whereas CA1 stratum oriens received more contralateral innervation. Interestingly, ipsilateral connections dominated for both CA2–CA1 stratum oriens and CA2–CA1 stratum radiatum. These results demonstrate that the primary intrahippocampal target of CA2 pyramidal cells is the ipsilateral CA1 stratum oriens, in contrast to CA3 cells which project more diversely to bilateral CA1 regions. Such innervation patterns may suggest differential dendritic information processing in apical and basal dendrites of CA1 pyramidal cells.
Ipsilateral and contralateral hippocampal CA3–CA1 and CA2–CA1 projections were investigated in adult male Long–Evans rats by retrograde tracing. Injection of the retrograde tracer cholera toxin subunit B in the strata oriens and radiatum of dorsal CA1 resulted in labeling of predominantly pyramidal cells in ipsilateral and contralateral CA3 and CA2.
Modern pain-control theory predicts that a loss of inhibition (disinhibition) in the dorsal horn of the spinal cord is a crucial substrate for chronic pain syndromes. However, the nature of the ...mechanisms that underlie such disinhibition has remained controversial. Here we present evidence for a novel mechanism of disinhibition following peripheral nerve injury. It involves a trans-synaptic reduction in the expression of the potassium-chloride exporter KCC2, and the consequent disruption of anion homeostasis in neurons of lamina I of the superficial dorsal horn, one of the main spinal nociceptive output pathways. In our experiments, the resulting shift in the transmembrane anion gradient caused normally inhibitory anionic synaptic currents to be excitatory, substantially driving up the net excitability of lamina I neurons. Local blockade or knock-down of the spinal KCC2 exporter in intact rats markedly reduced the nociceptive threshold, confirming that the reported disruption of anion homeostasis in lamina I neurons was sufficient to cause neuropathic pain.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Epileptic seizures are characterized by synchronized discharges of neurons, leading to the activation of inflammatory responses that in turn contributes to seizure progression. Berberine (BBR), a ...bioactive constituent extracted from berberis, has been known to relieve seizures in rodent models. In this study, we synthesized two derivatives of berberine (BBR-D1 and BBR-D2) to compare their seizure reducing effect with BBR in pentylenetetrazole (PTZ)-induced seizures in zebrafish. We found a structure-activity relationship between hydrophilic/hydrophobic composition of the derivatives and their anticonvulsant activity. We also investigated the underlying mechanism related to their anti-inflammatory effect during seizures. BBR and its derivatives increased the seizure onset latency and suppressed the seizure-like behavior after PTZ treatment. Zebrafish larvae pretreated with BBR and its derivatives showed recovery on c-fos expression and neuronal discharges during seizures. The inflammatory responses occurred during the progression of seizures, including the recruitment of macrophages and neutrophils as well as an up-regulation of tumor necrosis factor alpha (TNFα), interleukin 1 beta (il1β), and interleukin 6 (il6). This effect was significantly suppressed by the pretreatment of BBR and its derivatives. Our results suggest that BBR and its derivatives attenuate PTZ-induced seizures and modulate anti-inflammatory effect to potentially protect zebrafish from the occurrence of further seizures. From the tested compounds, BBR-D1 (the hydrophilic berberrubine) showed the strongest seizure reducing effect.
Graphical Abstract
Two derivatives of berberine (BBR-D1 and BBR-D2) were synthesized to compare their seizure reducing effect with BBR in pentylenetetrazole (PTZ)-induced seizures in zebrafish. BBR and its derivatives increased the seizure onset latency and suppressed the seizure-like behavior after PTZ treatment. Zebrafish larvae pretreated with BBR and its derivatives showed recovery on c-fos expression and neuronal discharges during seizures. The inflammatory responses occurred during the progression of seizures, including the recruitment of macrophages and neutrophils as well as an up-regulation of tumor necrosis factor alpha (TNFα), interleukin 1 beta (il1β), and interleukin 6 (il6). This effect was significantly suppressed by the pretreatment of BBR and its derivatives.
To understand the functional significance and mechanisms of action in the CNS of endogenous and exogenous cannabinoids, it is crucial to identify the neural elements that serve as the structural ...substrate of these actions. We used a recently developed antibody against the CB1 cannabinoid receptor to study this question in hippocampal networks. Interneurons with features typical of basket cells showed a selective, intense staining for CB1 in all hippocampal subfields and layers. Most of them (85.6%) contained cholecystokinin (CCK), which corresponded to 96.9% of all CCK-positive interneurons, whereas only 4.6% of the parvalbumin (PV)-containing basket cells expressed CB1. Accordingly, electron microscopy revealed that CB1-immunoreactive axon terminals of CCK-containing basket cells surrounded the somata and proximal dendrites of pyramidal neurons, whereas PV-positive basket cell terminals in similar locations were negative for CB1. The synthetic cannabinoid agonist WIN 55,212-2 (0.01-3 microM) reduced dose-dependently the electrical field stimulation-induced 3HGABA release from superfused hippocampal slices, with an EC50 value of 0. 041 microM. Inhibition of GABA release by WIN 55,212-2 was not mediated by inhibition of glutamatergic transmission because the WIN 55,212-2 effect was not reduced by the glutamate blockers AP5 and CNQX. In contrast, the CB1 cannabinoid receptor antagonist SR 141716A (1 microM) prevented this effect, whereas by itself it did not change the outflow of 3HGABA. These results suggest that cannabinoid-mediated modulation of hippocampal interneuron networks operate largely via presynaptic receptors on CCK-immunoreactive basket cell terminals. Reduction of GABA release from these terminals is the likely mechanism by which both endogenous and exogenous CB1 ligands interfere with hippocampal network oscillations and associated cognitive functions.
Effective chemical compound toxicity screening is of paramount importance for safe cardiac drug development. Using mammals in preliminary screening for detection of cardiac dysfunction by ...electrocardiography (ECG) is costly and requires a large number of animals. Alternatively, zebrafish embryos can be used as the ECG waveform is similar to mammals, a minimal amount of chemical is necessary for drug testing, while embryos are abundant, inexpensive and represent replacement in animal research with reduced bioethical concerns. We demonstrate here the utility of pre-feeding stage zebrafish larvae in detection of cardiac dysfunction by electrocardiography. We have optimised an ECG recording system by addressing key parameters such as the form of immobilization, recording temperature, electrode positioning and developmental age. Furthermore, analysis of 3 days post fertilization (dpf) zebrafish embryos treated with known QT prolonging drugs such as terfenadine, verapamil and haloperidol led to reproducible detection of QT prolongation as previously shown for adult zebrafish. In addition, calculation of Z-factor scores revealed that the assay was sensitive and specific enough to detect large drug-induced changes in QTc intervals. Thus, the ECG recording system is a useful drug-screening tool to detect alteration to cardiac cycle components and secondary effects such as heart block and arrhythmias in zebrafish larvae before free feeding stage, and thus provides a suitable replacement for mammalian experimentation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
During COVID-19 lockdown the enforced social isolation and other pandemic-related changes highly increased the risk of mental health problems. We aimed to discover how elderly people coped with the ...psychological burdens of pandemic and the social isolation in Hungary.
This study included 589 (441 females) Hungarian individuals, aged 60-83 (M = 68.1, SD = 4.46). We collected online survey data to reach a wide population of elderly. Results of hierarchical linear modelling and structural equation modelling (SEM) analyses established how the current life-changing circumstances, the intolerance of uncertainty, loneliness and social support influence the mental health (e.g. depression, anxiety, well-being) of the elderly. The model was used to explore how adaptive and maladaptive emotion regulation strategies mediated the effects.
Findings showed that perceived change in mood, social connectedness, and quality of life was negatively affected by catastrophizing and loneliness; whereas positive refocusing and contamination fear had a positive effect. According to the SEM analysis, intolerance of uncertainty and loneliness directly affected mental health. Further, maladaptive emotion regulation strategies mediated the connection between intolerance of uncertainty, contamination fear, loneliness and mental health. Whereas adaptive emotion regulation strategy mediated the connection between social support from friends, contamination fear, loneliness and mental health.
Overall, our research might help the understanding of how external and internal factors contributed to the well-being of elderly people during the COVID-19. The model can also be translated into professional interventions to develop coping strategies among elderly for the challenges of COVID-19 pandemic in their lives.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
The Ca2+/calmodulin-dependent protein phosphatase 2B or calcineurin (CN) participates in several Ca2+-dependent signal transduction cascades and, thus, contributes to the short and long term ...regulation of neuronal excitability. By using a specific antibody to CN, we demonstrate its absence from hippocampal interneurons and illustrate a physiological consequence of such CN deficiency. Consistent with the lack of CN in interneurons as detected by immunocytochemistry, the CN inhibitors FK-506 or okadaic acid significantly prolonged N-methyl-D-aspartate channel openings recorded in the cell-attached mode in hippocampal principal cells but not those recorded in interneurons. Interneurons were also devoid of Ca2+/calmodulin-dependent protein kinase IIα , yet many of their nuclei contained the cyclic AMP-responsive element binding protein. On the basis of the CN and Ca2+/calmodulin-dependent protein kinase IIα deficiency of interneurons, entirely different biochemical mechanisms are expected to govern Ca2+-dependent neuronal plasticity in interneurons versus principal cells.
Assessment of heart function in zebrafish larvae using electrocardiography (ECG) is a potentially useful tool in developing cardiac treatments and the assessment of drug therapies. In order to better ...understand how a measured ECG waveform is related to the structure of the heart, its position within the larva and the position of the electrodes, a 3D model of a 3 days post fertilisation (dpf) larval zebrafish was developed to simulate cardiac electrical activity and investigate the voltage distribution throughout the body. The geometry consisted of two main components; the zebrafish body was modelled as a homogeneous volume, while the heart was split into five distinct regions (sinoatrial region, atrial wall, atrioventricular band, ventricular wall and heart chambers). Similarly, the electrical model consisted of two parts with the body described by Laplace's equation and the heart using a bidomain ionic model based upon the Fitzhugh-Nagumo equations. Each region of the heart was differentiated by action potential (AP) parameters and activation wave conduction velocities, which were fitted and scaled based on previously published experimental results. ECG measurements in vivo at different electrode recording positions were then compared to the model results. The model was able to simulate action potentials, wave propagation and all the major features (P wave, R wave, T wave) of the ECG, as well as polarity of the peaks observed at each position. This model was based upon our current understanding of the structure of the normal zebrafish larval heart. Further development would enable us to incorporate features associated with the diseased heart and hence assist in the interpretation of larval zebrafish ECGs in these conditions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Most metazoan embryos commence development with rapid, transcriptionally silent cell divisions, with genome activation delayed until the mid-blastula transition (MBT). However, a set of genes escapes ...global repression and gets activated before MBT. Here we describe the formation and the spatio-temporal dynamics of a pair of distinct transcription compartments, which encompasses the earliest gene expression in zebrafish. 4D imaging of pri-miR430 and zinc-finger-gene activities by a novel, native transcription imaging approach reveals transcriptional sharing of nuclear compartments, which are regulated by homologous chromosome organisation. These compartments carry the majority of nascent-RNAs and active Polymerase II, are chromatin-depleted and represent the main sites of detectable transcription before MBT. Transcription occurs during the S-phase of increasingly permissive cleavage cycles. It is proposed, that the transcription compartment is part of the regulatory architecture of embryonic nuclei and offers a transcriptionally competent environment to facilitate early escape from repression before global genome activation.
Dentate granule cells communicate with their postsynaptic targets by three distinct terminal types. These include the large mossy terminals, filopodial extensions of the mossy terminals, and smaller ...en passant synaptic varicosities. We examined the postsynaptic targets of mossy fibers by combining in vivo intracellular labeling of granule cells, immunocytochemistry, and electron microscopy. Single granule cells formed large, complex "mossy" synapses on 11-15 CA3 pyramidal cells and 7-12 hilar mossy cells. In contrast, GABAergic interneurons, identified with immunostaining for substance P-receptor, parvalbumin, and mGluR1a-receptor, were selectively innervated by very thin (filopodial) extensions of the mossy terminals and by small en passant boutons in both the hilar and CA3 regions. These terminals formed single, often perforated, asymmetric synapses on the cell bodies, dendrites, and spines of GABAergic interneurons. The number of filopodial extensions and small terminals was 10 times larger than the number of mossy terminals. These findings show that in contrast to cortical pyramidal neurons, (1) granule cells developed distinct types of terminals to affect interneurons and pyramidal cells and (2) they innervated more inhibitory than excitatory cells. These findings may explain the physiological observations that increased activity of granule cells suppresses the overall excitability of the CA3 recurrent system and may form the structural basis of the target-dependent regulation of glutamate release in the mossy fiber system.
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