DHA supplementation enhances high-frequency, stimulation-induced synaptic transmission in mouse hippocampus

2012 ◽  
Vol 37 (5) ◽  
pp. 880-887 ◽  
Author(s):  
Steve Connor ◽  
Gustavo Tenorio ◽  
Michael Tom Clandinin ◽  
Yves Sauvé
Keyword(s):  
Synaptic Transmission ◽  
High Frequency ◽  
Control Group ◽  
High Frequency Stimulation ◽  
Spatial Learning And Memory ◽  
Mouse Hippocampus ◽  
Spatial Memories ◽  
Frequency Stimulation ◽  
Activity Dependent ◽  
Synaptic Responses

While some studies on dietary supplementation with docosahexaenoic acid (DHA, 22:6n-3) have reported a beneficial effect on memory as a function of age, others have failed to find any effect. To clarify this issue, we sought to determine whether supplementing mice with a DHA-enriched diet could alter the ability of synapses to undergo activity-dependent changes in the hippocampus, a brain structure involved in forming new spatial memories. We found that DHA was increased by 29% ± 5% (mean ± SE) in the hippocampus for the supplemented (DHA+) versus nonsupplemented (control) group (n = 5 mice per group; p < 0.05). Such DHA elevation was associated with enhanced synaptic transmission (p < 0.05) as assessed by application of a high-frequency electrical stimulation protocol (100 Hz stimulation, which induced transient (<2 h) increases in synaptic strength) to slices from DHA+ (n = 4 mice) hippocampi when compared with controls (n = 4 mice). Increased synaptic responses were evident 60 min poststimulation. These results suggest that dietary DHA supplementation facilitates synaptic plasticity following brief high-frequency stimulation. This increase in synaptic transmission might provide a physiological correlation for the improved spatial learning and memory observed following DHA supplementation.

Activity-Dependent Release of Adenosine Contributes to Short-Term Depression at CA3-CA1 Synapses in Rat Hippocampus

2003 ◽  
Vol 89 (1) ◽  
pp. 22-26 ◽  
Author(s):  
Darrin H. Brager ◽  
Scott M. Thompson
Keyword(s):  
Receptor Antagonist ◽  
High Frequency ◽  
High Frequency Stimulation ◽  
Short Term ◽  
Transport Inhibitor ◽  
Vesicular Release ◽  
Organotypic Slice Cultures ◽  
Adenosine Transport ◽  
Frequency Stimulation ◽  
Activity Dependent

High-frequency stimulation results in a transient, presynaptically mediated decrease in synaptic efficacy called short-term depression (STD). Stimulation of Schaffer-collateral axons at 10 Hz for 5 s resulted in approximately 75% depression of excitatory postsynaptic current (EPSC) slope recorded from CA1 cells in rat organotypic slice cultures. An adenosine A1 receptor antagonist decreased the magnitude of STD elicited with 10-Hz stimulation by approximately 30%. The A1 receptor antagonist had no effect on STD elicited with 3-Hz stimulation. The activation of A1 receptors during 10-Hz stimulation was not due to the extracellular conversion of released ATP to adenosine, because block of 5′-ectonucleotidases did not significantly affect STD. The adenosine transport inhibitor dipyridamole did not reduce STD, indicating that adenosine was not released by facilitated transport. We conclude that 10-Hz, but not 3-Hz, stimulation causes the vesicular release of adenosine and the rapid (<3 s) activation of presynaptic inhibitory A1 receptors, which account for approximately 40% of homosynaptic EPSC depression.

Medial amygdala enhances synaptic transmission and synaptic plasticity in the dentate gyrus of rats in vivo

1995 ◽  
Vol 74 (5) ◽  
pp. 2201-2203 ◽  
Author(s):  
Y. Ikegaya ◽  
K. Abe ◽  
H. Saito ◽  
N. Nishiyama
Keyword(s):  
Synaptic Plasticity ◽  
Synaptic Transmission ◽  
Dentate Gyrus ◽  
High Frequency ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Medial Amygdala ◽  
Frequency Stimulation ◽  
Stimulation Of

1. The present experiment was designed to test whether synaptic transmission and synaptic plasticity in the dentate gyrus were modulated by the medial amygdala (MeA). Field potentials in the dentate gyrus (DG) evoked by stimulations of the medial perforant path (PP) were extracellularly recorded in anesthetized rats. 2. Although single-pulse stimulation of the MeA augmented PP stimulation-evoked population spike amplitude in the DG transiently, high-frequency stimulation (100 Hz for 1 s) of the MeA induced long-lasting enhancement of synaptic transmission that was not occluded by PP tetanus-induced long-term potentiation (LTP). 3. When high-frequency stimulation of the MeA was applied concurrently with weak tetanus of the PP, which alone induced only marginal LTP, the magnitude of LTP increased considerably. 4. These results demonstrate that neuron activities in the MeA induce short- and long-lasting changes in the excitability of the PP-DG synapses and thereby enhance their synaptic plasticity.

Regulation of synaptic responses to high-frequency stimulation and LTP by neurotrophins in the hippocampus

Nature ◽  
1996 ◽  
Vol 381 (6584) ◽  
pp. 706-709 ◽  
Author(s):  
Alexander Figurov ◽  
Lucas D. Pozzo-Miller ◽  
Petur Olafsson ◽  
Ti Wang ◽  
Bai Lu
Keyword(s):  
High Frequency ◽  
High Frequency Stimulation ◽  
Frequency Stimulation ◽  
Synaptic Responses

scholarly journals Synaptically Released Glutamate Does Not Overwhelm Transporters on Hippocampal Astrocytes During High-Frequency Stimulation

2000 ◽  
Vol 83 (5) ◽  
pp. 2835-2843 ◽  
Author(s):  
Jeffrey S. Diamond ◽  
Craig E. Jahr
Keyword(s):  
Synaptic Transmission ◽  
High Frequency ◽  
Hippocampal Slices ◽  
Synaptic Cleft ◽  
Long Term Potentiation ◽  
High Frequency Stimulation ◽  
Direct Role ◽  
Ca1 Region ◽  
Frequency Stimulation ◽  
Hippocampal Astrocytes

In addition to maintaining the extracellular glutamate concentration at low ambient levels, high-affinity glutamate transporters play a direct role in synaptic transmission by speeding the clearance of glutamate from the synaptic cleft and limiting the extent to which transmitter spills over between synapses. Transporters are expressed in both neurons and glia, but glial transporters are likely to play the major role in removing synaptically released glutamate from the extracellular space. The role of transporters in synaptic transmission has been studied directly by measuring synaptically activated, transporter-mediated currents (STCs) in neurons and astrocytes. Here we record from astrocytes in the CA1 region of hippocampal slices and elicit STCs with high-frequency (100 Hz) stimulus trains of varying length to determine whether transporters are overwhelmed by stimuli that induce long-term potentiation. We show that, at near-physiological temperatures (34°C), high-frequency stimulation (HFS) does not affect the rate at which transporters clear glutamate from the extrasynaptic space. Thus, although spillover between synapses during “normal” stimulation may compromise the absolute synapse specificity of fast excitatory synaptic transmission, spillover is not exacerbated during HFS. Transporter capacity is diminished somewhat at room temperature (24°C), although transmitter released during brief, “theta burst” stimulation is still cleared as quickly as following a single stimulus, even when transport capacity is partially diminished by pharmacological means.

scholarly journals Serendipitous Stimulation of Nucleus Basalis of Meynert—The Effect of Unintentional, Long-Term High-Frequency Stimulation on Cognition in Parkinson’s Disease

2022 ◽  
Vol 11 (2) ◽  
pp. 337
Author(s):  
I. Daria Bogdan ◽  
D. L. Marinus Oterdoom ◽  
Teus van Laar ◽  
Rients B. Huitema ◽  
Vincent J. Odekerken ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
High Frequency ◽  
Low Frequency ◽  
Nucleus Basalis ◽  
Nucleus Basalis Of Meynert ◽  
Control Group ◽  
High Frequency Stimulation ◽  
Internal Globus Pallidus ◽  
Frequency Stimulation

There is a growing interest in deep brain stimulation (DBS) of the nucleus basalis of Meynert (NBM) as a potential therapeutic modality for Parkinson’s disease dementia (PDD). Low-frequency stimulation has yielded encouraging results in individual patients; however, these are not yet sustained in larger studies. With the aim to expand the understanding of NBM-DBS, we share our experience with serendipitous NBM-DBS in patients treated with DBS of the internal Globus pallidus (GPi) for Parkinson’s disease. Since NBM is anatomically located ventral to GPi, several GPi-treated patients appeared to have the distal contact of DBS-electrode(s) positioned in the NBM. We hypothesized that unintentional high-frequency NBM-DBS over a period of one year would result in the opposite effect of low-frequency NBM-stimulation and cause cognitive decline. We studied a cohort of 33 patients with bilateral high-frequency DBS in the GPi for Parkinson’s disease, of which twelve were unintentionally co-stimulated in NBM. The subgroups of unintentional unilateral (N = 7) and bilateral NBM-DBS (N = 5) were compared to the control group of bilateral GPi-DBS (N = 11). Here, we show that unintentional high-frequency NBM-DBS did not cause a significantly faster decline in cognitive function. Further research is warranted for characterizing the therapeutic role of NBM-DBS.

Effect of Transcutaneous Electrical Acupuncture Point Stimulation at Different Frequencies in a Rat Model of Neuropathic Pain

2017 ◽  
Vol 35 (2) ◽  
pp. 142-147 ◽  
Author(s):  
Xiangdi Yu ◽  
Fangxiang Zhang ◽  
Bingning Chen
Keyword(s):  
Neuropathic Pain ◽  
Rat Model ◽  
High Frequency ◽  
Low Frequency ◽  
Acupuncture Point ◽  
Control Group ◽  
High Frequency Stimulation ◽  
Sprague Dawley ◽  
Electrical Acupuncture ◽  
Frequency Stimulation

Background Acupuncture and related techniques are used worldwide to alleviate pain; however, their mechanisms of action are still not fully understood. In the present study, we investigated the effect of transcutaneous electrical acupuncture point stimulation (TEAS) at different frequencies in a chronic constriction injury (CCI) model of neuropathic pain in rats. Methods CCI was induced by ligating the common sciatic nerve, which produced neuropathic pain. 18 male Sprague–Dawley rats with CCI were randomly divided into three groups (n=6 each) that remained untreated (CCI group) or received TEAS at high frequency (CCI+TEAS-H group) or TEAS at low frequency (CCI+TEAS-L group). Rats in the CCI+TEAS-H group received high frequency stimulation (6–9 mA, 100 Hz) at GB34/GV26/ST36; those in the CCI+TEAS-L group received low frequency stimulation (6–9 mA, 2 Hz) at the same points. Rats in the control group had the same electrodes applied but received no stimulation. All three groups were subjected to behavioural studies after treatment. Expression of μ opioid receptors (MORs) in the L3–L5 dorsal root ganglion (DRG) was determined by immunofluorescence staining and Western blotting after treatment. Results Compared with the untreated CCI group, both mechanical allodynia and thermal hypergesia were significantly attenuated, and MOR expression in the DRG was significantly increased by low frequency TEAS treatment at GB34/GV26/ST36 (p<0.05). In contrast, no significant differences were observed between the CCI and CCI+TEAS-H groups. Conclusions The use of low frequency TEAS significantly mitigated neuropathic pain in this rat model, and its analgesic effect is likely mediated by upregulation of MOR expression in the DRG.

scholarly journals High-Frequency Stimulation Produces a Transient Blockade of Voltage-Gated Currents in Subthalamic Neurons

2001 ◽  
Vol 85 (4) ◽  
pp. 1351-1356 ◽  
Author(s):  
Corinne Beurrier ◽  
Bernard Bioulac ◽  
Jacques Audin ◽  
Constance Hammond
Keyword(s):  
Synaptic Transmission ◽  
High Frequency ◽  
High Frequency Stimulation ◽  
Voltage Gated ◽  
Cationic Current ◽  
Spontaneous Activities ◽  
Single Spike ◽  
Frequency Stimulation ◽  
Subthalamic Neurons

The effect of high-frequency stimulation (HFS) of the subthalamic nucleus (STN) was analyzed with patch-clamp techniques (whole cell configuration, current- and voltage-clamp modes) in rat STN slices in vitro. A brief tetanus, consisting of 100-μs bipolar stimuli at a frequency of 100–250 Hz during 1 min, produced a full blockade of ongoing STN activity whether it was in the tonic or bursting mode. This HFS-induced silence lasted around 6 min after the end of stimulation, was frequency dependent, could be repeated without alteration, and was not synaptically induced as it was still observed in the presence of blockers of ionotropic GABA and glutamate receptors or in the presence of cobalt at a concentration (2 mM) that blocks voltage-gated Ca2+ channels and synaptic transmission. During HFS-induced silence, the following alterations were observed: the persistent Na+ current ( I NaP) was totally blocked (by 99%), the Ca2+-mediated responses were strongly reduced including the posthyperpolarization rebound (−62% in amplitude) and the plateau potential (−76% in duration), suggesting that T- and L-type Ca2+ currents are transiently depressed by HFS, whereas the Cs+-sensitive, hyperpolarization-activated cationic current ( I h) was little affected. Thus a high-frequency tetanus produces a blockade of the spontaneous activities of STN neurons as a result of a strong depression of intrinsic voltage-gated currents underlying single-spike and bursting modes of discharge. These effects of HFS, which are completely independent of synaptic transmission, provide a mechanism for interrupting ongoing activities of STN neurons.

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