scholarly journals Stereological Evidence of Non-Selective Hippocampal Neurodegeneration, Growth Factors Depletion, and Behavioral Deficit Following Short-Term Bilateral Adrenalectomy in Wistar Rats 

2021 ◽  
Author(s):  
Naserddine Hamadi ◽  
Ömür Deniz ◽  
Ahlam Abi Issa ◽  
Naheed Amir ◽  
Saeed Minhas ◽  
...  
Keyword(s):  
Growth Factor ◽  
Hippocampal Neurons ◽  
Wistar Rats ◽  
Neuronal Degeneration ◽  
Pyramidal Cells ◽  
Underlying Mechanism ◽  
Short Term ◽  
Area 7 ◽  
Ca1 Area ◽  
The Impact

Abstract In the current study we investigated the impact of short-term adrenalectomy on hippocampal neurons of Wistar rats. In addition, the underlying mechanism(s) of degeneration in these neurons was investigated by measuring the levels of insulin-like growth factor-1 and β-nerve growth factor. Moreover, we investigated the cognitive behavior in these rats. The stereological counting in the hippocampus revealed a significant neuronal death in the dentate gyrus and CA3, but not in the CA2 and CA1, area 7 and 14 days post adrenalectomy. The ultrastructural examinations revealed degenerated and degenerating neurons only in the dentate as well as CA4, and CA3 areas over the course of 3, 7 and 14 days. The levels of IGF-1 were significantly decreased in the hippocampus of ADX rats 12 h post adrenalectomy and lasted over the course of two weeks. However, β-NGF was significantly reduced in ADX rats only at 14 days postoperatively. Using passive avoidance test we found a cognitive deficit in the ADX compared to the sham operated rats over time. In conclusion, both granule and pyramidal cells were degenerated in the hippocampus following short-term adrenalectomy. The early depletion of IGF-1 might play a role in the hippocampal neuronal degeneration. Consequently, the loss of the hippocampal neurons after adrenalectomy leads to cognitive deficits.

Electrophysiological evidence from glutamate microapplications for local excitatory circuits in the CA1 area of rat hippocampal slices

1988 ◽  
Vol 59 (1) ◽  
pp. 110-123 ◽  
Author(s):  
E. P. Christian ◽  
F. E. Dudek
Keyword(s):  
Hippocampal Neurons ◽  
Hippocampal Slices ◽  
Pyramidal Cells ◽  
Inhibitory Synapses ◽  
Excitatory Synapses ◽  
Recording Site ◽  
Postsynaptic Potentials ◽  
Inhibitory Postsynaptic Potentials ◽  
Ca1 Area ◽  
Transverse Slice

1. Evidence for local excitatory synaptic connections in CA1 of the rat hippocampus was obtained by recording excitatory postsynaptic potentials (EPSPs) intracellularly from pyramidal cells during local microapplications of glutamate. 2. Experiments were performed in hippocampal slices cut parallel to (transverse slice) or perpendicular to (longitudinal slice) alvear fibers. In normal solutions, glutamate microdrops (10–20 mM, 10–20 micron diam) applied in CA1 within 400 micron of recorded cells sometimes increased the frequency of inhibitory postsynaptic potentials for 5–10 s in both transverse and longitudinal slices. Increases in EPSP frequency were also occasionally observed, but only in transverse slices. Tetrodotoxin (1 microgram/ml) blocked glutamate-induced increases in PSP frequency, thus indicating that they were not caused by subthreshold effects on presynaptic terminals. Increases in PSP frequency were interpreted to result from glutamate activation of hippocampal neurons with inhibitory and excitatory connections to recorded neurons. 3. In both slice orientations, local excitatory circuits were studied in more isolated conditions by surgically separating CA1 from CA3 (transverse slices) and by blocking GABAergic inhibitory synapses with picrotoxin (5–10 microM). Microdrops were systematically applied at 200 and 400 micron on each side of the recording site. Significant glutamate-induced increases in EPSP frequency were observed in neurons from both slice orientations to microdrops in at least one of the locations. This provided evidence that excitatory synapses are present in both transverse and longitudinal slices. 4. Substantial increases in EPSP frequency only occurred in neurons from longitudinal slices when glutamate was microapplied 200 micron or less from the recording site. In transverse slices, however, large increases in EPSP frequency were observed to glutamate microapplications at 200 or 400 micron. These data suggest that CA1 local excitatory connections project for longer distances in the transverse than in the longitudinal plane of section. 5. Increases in EPSP frequency, averaged across cells, did not differ significantly in the four microapplication sites in either transverse or longitudinal slices. Thus local excitation in CA1 does not appear to be asymmetrically arranged in the way suggested for CA3. 6. The densities of local excitatory circuits in CA1 versus CA3 were studied by quantitatively comparing glutamate-induced increases in EPSP frequency.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Basic FGF, NGF, and IGFs Protect Hippocampal and Cortical Neurons against Iron-Induced Degeneration

1993 ◽  
Vol 13 (3) ◽  
pp. 378-388 ◽  
Author(s):  
Ying Zhang ◽  
Tohru Tatsuno ◽  
John M. Carney ◽  
Mark P. Mattson
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Neuronal Degeneration ◽  
Cell Damage ◽  
Oxygen Radical ◽  
Neuroprotective Effects ◽  
In Vivo Models

Iron is believed to contribute to the process of cell damage and death resulting from ischemic and traumatic insults by catalyzing the oxidation of protein and lipids. Exposure of cultured rat hippocampal neurons to iron (FeSO4) caused a dose-dependent reduction in neuronal survival, which was potentiated by ascorbate. Damage to neurons was associated with a significant level of oxygen radical in the culture medium. The iron chelator desferal prevented both the neuronal degeneration caused by FeSO4 and the production of oxygen radical, demonstrating that ionic iron was responsible for the cell damage. Iron neurotoxicity was associated with an elevation of [Ca2+]i and was attenuated by NMDA receptor antagonists. Since recent findings demonstrated neuroprotective effects of growth factors in cell culture and in vivo models of ischemia, we examined the effects of growth factors on iron-induced damage. Basic fibroblast growth factor (bFGF), nerve growth factor (NGF), and insulinlike growth factors (IGF-I and IGF-II) each protected neurons against iron-induced damage. Both rat hippocampal and human cortical neurons were protected by these growth factors. Taken together, the data suggest that the neuroprotective effects of growth factors against excitotoxic/ischemic insults may result, in part, from a prevention or attenuation of oxidative damage.

scholarly journals Doc2-mediated superpriming supports synaptic augmentation

2018 ◽  
Vol 115 (24) ◽  
pp. E5605-E5613 ◽  
Author(s):  
Renhao Xue ◽  
David A. Ruhl ◽  
Joseph S. Briguglio ◽  
Alexander G. Figueroa ◽  
Robert A. Pearce ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Synaptic Plasticity ◽  
Learning And Memory ◽  
Synaptic Vesicles ◽  
Hippocampal Neurons ◽  
Underlying Mechanism ◽  
Short Term ◽  
Short Term Plasticity ◽  
Releasable Pool ◽  
Readily Releasable Pool

Various forms of synaptic plasticity underlie aspects of learning and memory. Synaptic augmentation is a form of short-term plasticity characterized by synaptic enhancement that persists for seconds following specific patterns of stimulation. The mechanisms underlying this form of plasticity are unclear but are thought to involve residual presynaptic Ca2+. Here, we report that augmentation was reduced in cultured mouse hippocampal neurons lacking the Ca2+ sensor, Doc2; other forms of short-term enhancement were unaffected. Doc2 binds Ca2+ and munc13 and translocates to the plasma membrane to drive augmentation. The underlying mechanism was not associated with changes in readily releasable pool size or Ca2+ dynamics, but rather resulted from superpriming a subset of synaptic vesicles. Hence, Doc2 forms part of the Ca2+-sensing apparatus for synaptic augmentation via a mechanism that is molecularly distinct from other forms of short-term plasticity.

Polychlorinated biphenyl induced hepatocyte alterations

1987 ◽  
Vol 45 ◽  
pp. 716-717
Author(s):  
D.N. Collins ◽  
J.N. Turner ◽  
K.O. Brosch ◽  
R.F. Seegal
Keyword(s):  
Lipid Droplets ◽  
Wistar Rats ◽  
Homovanillic Acid ◽  
Polychlorinated Biphenyl ◽  
Corn Oil ◽  
Environmental Pollutants ◽  
Short Term ◽  
Pcb Congeners ◽  
Urinary Levels ◽  
The Brain

Polychlorinated biphenyls (PCBs) are a ubiquitous class of environmental pollutants with toxic and hepatocellular effects, including accumulation of fat, proliferated smooth endoplasmic recticulum (SER), and concentric membrane arrays (CMAs) (1-3). The CMAs appear to be a membrane storage and degeneration organelle composed of a large number of concentric membrane layers usually surrounding one or more lipid droplets often with internalized membrane fragments (3). The present study documents liver alteration after a short term single dose exposure to PCBs with high chlorine content, and correlates them with reported animal weights and central nervous system (CNS) measures. In the brain PCB congeners were concentrated in particular regions (4) while catecholamine concentrations were decreased (4-6). Urinary levels of homovanillic acid a dopamine metabolite were evaluated (7).Wistar rats were gavaged with corn oil (6 controls), or with a 1:1 mixture of Aroclor 1254 and 1260 in corn oil at 500 or 1000 mg total PCB/kg (6 at each level).

A Newspaper’s Effect on the Strength of Automatic Associations in Memory

2012 ◽  
Vol 24 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Florian Arendt
Keyword(s):  
Treatment Group ◽  
Term Effect ◽  
Control Group ◽  
Implicit Measure ◽  
Short Term ◽  
Short Term Treatment ◽  
Short Term Effect ◽  
Automatic Associations ◽  
Foreign Nationality ◽  
The Impact

A test was done to see if reading a newspaper which consistently overrepresents foreigners as criminals strengthens the automatic association between foreign country and criminal in memory (i.e., implicit cultivation). Further, an investigation was done to find out if reading articles from the same newspaper produces a short-term effect on the same measure and if (1) emotionalization of the newspaper texts, (2) emotional reactions of the reader (indicated by arousal), and (3) attributed text credibility moderate the short-term treatment effect. Eighty-five participants were assigned to one of three experimental conditions. Participants in the control group received short factual crime texts, where the nationality of the offender was not mentioned. Participants in the factual treatment group received the same texts, but the foreign nationality was mentioned. Participants in the emotionalized treatment group received emotionalized articles (i.e., texts which are high in vividness and frequency) covering the same crimes, with the foreign nationality mentioned. Supporting empirical evidence for implicit cultivation and a short-term effect was found. However, only emotionalized articles produced a short-term effect on the strength of the automatic association, indicating that newspaper texts must have a minimum of stimulus intensity to overcome an effect threshold. There were no moderating effects of arousal or credibility pertaining to the impact on the implicit measure. However, credibility moderated the short-term effect on a first-order judgment (i.e., estimated frequency of foreigners of all criminals). This indicates that a newspaper’s effect on the strength of automatic associations is relatively independent from processes of propositional reasoning.

Diatoms in the Amur Bay sediments (Sea of Japan) and the impact of typhoons on their accumulation over the last 2000 years

2019 ◽  
pp. 252-256
Author(s):  
Irina A. Prushkovskaya ◽  
Ira B. Tsoy
Keyword(s):  
Sea Of Japan ◽  
Short Term ◽  
Catastrophic Events ◽  
Bromine Content ◽  
Amur Bay ◽  
The Impact

The study of diatoms in the sediments of the Amur Bay (Sea of Japan), formed over the last 2000 years, showed that the sharp short-term drops in the concentration of diatoms coincide with the minima of bromine content, which can be explained by the influence of typhoons or other catastrophic events leading to floods and used later in paleoreconstructions.

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