Effects of extracellular calcium on low frequency induced potentiation and habituation in the in vitro hippocampal slice preparation

1982 ◽  
Vol 60 (3) ◽  
pp. 266-275 ◽  
Author(s):  
R. W. Turner ◽  
J. J. Miller
Keyword(s):  
Evoked Potentials ◽  
Hippocampal Slice ◽  
Low Frequency ◽  
Extracellular Calcium ◽  
Population Spike ◽  
Slice Preparation ◽  
Short Term ◽  
High Calcium ◽  
Frequency Potentiation

The electrophysiological characteristics of frequency potentiation and habituation were investigated in two afferent systems of the in vitro hippocampal slice preparation. Low frequency stimulation (1 Hz) of the Schaffer collateral – commissural (Sch–comm) fibers results in a short-term potentiation of the amplitude and rate of rise of the EPSP and population spike responses recorded in the CA1 region. In contrast, 1-Hz stimulation of the perforant path (PP) evokes a short-term, habituation-like depression of the dentate granule cell EPSP and population spike. An inverse relationship was observed between stimulus intensity and the magnitude of frequency potentiation or habituation. Changes in afferent fiber volleys or general excitability of postsynaptic membranes did not contribute significantly to the development of either of these forms of short-term plasticity. Perfusion with a medium containing a high calcium – low magnesium concentration (4 mM Ca+2 and 1 mM Mg+2) produced a differential effect on CA1 and dentate evoked potentials. Following a 20-min exposure to this medium, the amplitude of CA1 potentials was increased while dentate responses were decreased. Frequency potentiation of CA1 responses and habituation of dentate responses were depressed or eliminated by the high calcium medium.The opposing influence of extracellular calcium on CA1 and dentate evoked potentials indicates a fundamental difference in the process of transmitter release in these systems, a characteristic that may contribute to the production of frequency potentiation and habituation.

Adaptation to calcium deprivation in the rat: effects of parathyroidectomy.

1977 ◽  
Vol 232 (3) ◽  
pp. E336
Author(s):  
J T Pento ◽  
L C Waite ◽  
P J Tracy ◽  
A D Kenny
Keyword(s):  
Adaptive Response ◽  
Calcium Transport ◽  
Parathyroid Tissue ◽  
Adaptation Period ◽  
Short Term ◽  
High Calcium

The role of parathyroid hormone (PTH) in the adaptive response in gut calcium transport to calcium deprivation has been studied in the rat using both the in vitro everted duodenal sac and the in situ ligated duodenal segment technique. Intact or parathyroidectomized (PTX) young rats were placed on a low calcium (0.01%) diet for 7-, 14-, or 21-day adaptation periods and compared with control rats maintained on a high calcium (1.5%) diet. Prior PTX (3 days before the start of the adaptation period) abolished the adaptive response (enhanced calcium transport) induced by calcium deprivation for a 7-day adaptation period, but did not abolish a response after a 21-day period. A 14-day adaptation period gave equivocal results. It is concluded that PTH appears to be necessary for short-term (7-day) adaptation, but not for long-term (21-day) adaptation to calcium deprivation. However, if accessory parathyroid tissue is present, the data could be interpreted differently: the essentiality of PTH for the adaptive response might be independent of the length of the adaptation period. The data also contribute to a possible resolution of the controversy concerning the involvement of PTH in the regulation of intestinal calcium transport in the rat.

Effects of anticonvulsant lactams on in vitro seizures in the hippocampal slice preparation

1999 ◽  
Vol 37 (2) ◽  
pp. 121-131 ◽  
Author(s):  
Matthew W. Hill ◽  
Maria Antonette M. de la Cruz ◽  
Douglas F. Covey ◽  
Steven M. Rothman
Keyword(s):  
Hippocampal Slice ◽  
Slice Preparation

Afferent and association fiber differences in short-term potentiation in piriform (olfactory) cortex of the rat

1990 ◽  
Vol 64 (1) ◽  
pp. 179-190 ◽  
Author(s):  
M. E. Hasselmo ◽  
J. M. Bower
Keyword(s):  
Time Constant ◽  
Piriform Cortex ◽  
Low Frequency ◽  
Pyramidal Cells ◽  
Olfactory Cortex ◽  
Short Term ◽  
Term Potentiation ◽  
Association Fibers ◽  
Stimulation Of

1. The effects of low-frequency stimulus trains on synaptically evoked responses in piriform cortex pyramidal cells were studied by the use of intracellular recording techniques in an in vitro slice preparation. Afferent and association fiber systems were differentially stimulated with electrodes placed in layer 1a or layer 1b, respectively. To quantify synapse modifiability, the heights of postsynaptic potentials (PSPs) elicited by paired-pulse stimulation (100-ms interval) were averaged over a 50-s period before and after a set of 10 stimulus trains (10 pulses each, 20 Hz, 5-s interpulse interval). 2. Afferent and association fibers showed consistent differences in their response to stimulation during the period lasting from approximately 10 to 200 s after presentation of trains. During this time period, the responses to stimulation of association fibers in layer 1b displayed a short-term potentiation, which over the 10 posttrain trials, produced an average increase in PSP height of 23.2 +/- 3.7% (mean +/- SE). On the other hand, responses to layer 1a stimulation showed an average depression of 10.9 +/- 3.6%. Layer 1b potentiation decayed with time constant roughly estimated at 79 s. Layer 1b potentiation appeared even at very low stimulus voltages and after local association fiber input had been cut, suggesting that it was largely a monosynaptic effect. 3. In the period immediately after train presentations, responses evoked by both layers showed a short-term augmentation with a time constant around 3 s. In layer 1a, this augmentation was superimposed on a depression with slow recovery. At longer times after train presentation (greater than 5 min), 2 cells out of 46 showed changes (increases) in synaptic efficacy in response to layer 1b stimulation. 4. In the current experiments both layers 1a and 1b showed statistically significant facilitation before the presentation of stimulus trains. However, layer 1b facilitation decreased from 22.7 +/- 3.5% to a statistically insignificant 3.9 +/- 3.3% after the presentation of trains, whereas layer 1a facilitation remained at a statistically significant level of 23.1 +/- 5.7%. 5. These experiments show that pyramidal cell responses to stimulation of the afferent and association fiber systems are affected differently by the previous presentation of trains of stimuli. This suggests that mechanisms of synaptic modification may differ between the afferent and intrinsic association synaptic projections onto single pyramidal cells in olfactory cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Lymphocyte cytoskeleton reorganization caused by a short-term action of an extremely low frequency electromagnetic field (50 Hz) on the blood in vitro

2020 ◽  
pp. 92-98
Author(s):  
A. N. Shklyarova ◽  
E. V. Tsukanova ◽  
M. N. Starodubtseva ◽  
I. A. Cheshik
Keyword(s):  
Mechanical Properties ◽  
Electromagnetic Field ◽  
Elastic Modulus ◽  
Whole Blood ◽  
Low Frequency ◽  
System Component ◽  
Short Term ◽  
Extremely Low Frequency ◽  
Atomic Force

Objective: to detect changes in the parameters of the structure and mechanical properties of the surface layer of lymphocytes in the blood of a rat after a single action (30 min and 2 h) of an extremely low frequency electromagnetic field (ELF EMF) on the rat`s whole blood in vitro.Material and methods. We exposed the whole blood of a Wistar rat (4.5 months) to the effect of ELF EMF (50 Hz, B = 0.79 mT), generated by an experimental setup based on a Helmholtz coil. Lymphocytes were isolated from the blood using the Histopaque-1077 density gradient sedimentation method, then were placed on the surface of glass slides and fixed with glutaraldehyde, and finally were dried. We performed atomic force microscopy (AFM) using the atomic force microscope Bioscope Resolve in the PeakForce QMN mode in air.Results. On the basis of the results of the analysis of the AFM images, we classified the lymphocytes into several morphological types depending on the size of the lamellopodium. We analyzed the mechanical properties of the surface areas sized 250 nm × 250 nm for lymphocytes with the lamellopodium sized 400–1100 nm. The analysis found an rise in the elastic modulus of the lymphocyte surface after a short-term action (30 min) of ELF EMF. When the time of the ELF EMF exposure was increased up to 2 hours, the elastic (elastic modulus) and adhesive properties (the adhesion force between the AFM probe tip and cell surface) of the lymphocytes were significantly weakened.Conclusion. For the first time using the AFM method we have detected nanoscale changes in the structure and mechanical properties of the surface of the rat`s lymphocytes after a short-term action of ELF EMF (50 Hz, 0.79 mT, 30 min), which are indicative of the activation of the functions of lymphocytes as an immune system component in response to the short-term exposure of ELF EMF.

scholarly journals In Vitro Control of Genes Critical for Parathyroid Embryogenesis by Extracellular Calcium

2020 ◽  
Vol 4 (7) ◽  
Author(s):  
Sergio Fabbri ◽  
Roberto Zonefrati ◽  
Gianna Galli ◽  
Giorgio Gronchi ◽  
Giuliano Perigli ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Mrna Expression ◽  
Extracellular Calcium ◽  
Variable Response ◽  
Messenger Ribonucleic Acid ◽  
Low Calcium ◽  
Parathyroid Function ◽  
High Calcium

Abstract Background The expression of the parathyroid transcription factors, encoded by the genes GATA3, GCM2, and MAFB, persists after parathyroid morphogenesis. This suggests a role of these genes in the regulatory program that governs parathyroid function in the adult. Indeed, these 3 genes form a transcriptional cascade able to activate PTH gene expression. Materials and Methods Adult adenoma parathyroid tissues were put in primary cell culture to evaluate the messenger ribonucleic acid (mRNA) expression of the PTH gene, of the genes involved in the calcium regulatory signaling pathway (CaSR, GNA11, and AP2S1), and of the 3 genes (GATA3, GCM2, and MAFB) involved in the parathyroid morphogenesis in the presence of different extracellular calcium concentrations from 0.1 mM to 3.0 mM. Aim The aim of the study was to investigate whether different extracellular calcium conditions could control the expression of transcription factors critical for parathyroid embryogenesis. Results The results of the experiments showed that the mRNA expression of GATA3, GCM2, and MAFB genes follows the same response as the PTH gene to extracellular calcium concentrations, with the highest expression at low calcium (0.1 mM) and the lowest at high calcium (3.0 mM). Conversely, the genes involved in the calcium signaling in the parathyroid cells showed a variable response to the extracellular calcium concentrations, with the CaSR and GNA11 genes exhibiting a sensitivity to low calcium concentrations. Conclusions These findings indicate that transcription factors recognized for their role in parathyroid embryogenesis show a response to extracellular calcium later in adulthood that parallels the behavior of the PTH gene.

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