scholarly journals The 5-Hydroxytryptamine4 Receptor Exhibits Frequency-dependent Properties in Synaptic Plasticity and Behavioural Metaplasticity in the Hippocampal CA1 Region In vivo

2004 ◽  
Vol 15 (7) ◽  
pp. 1037-1043 ◽  
Author(s):  
Anne Kemp ◽  
Denise Manahan-Vaughan
Keyword(s):  
Synaptic Plasticity ◽  
Frequency Dependent ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1

Low, but Not High, Doses of Copper Sulfate Impair Synaptic Plasticity in the Hippocampal CA1 Region In Vivo

2018 ◽  
Vol 185 (1) ◽  
pp. 143-147 ◽  
Author(s):  
Abolfazl Jand ◽  
Mohammad Reza Taheri-nejad ◽  
Masoumeh Mosleh ◽  
Mohammad Reza Palizvan
Keyword(s):  
Synaptic Plasticity ◽  
Copper Sulfate ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
High Doses

Noradrenergic Regulation of Synaptic Plasticity in the Hippocampal CA1 Region

1997 ◽  
Vol 77 (6) ◽  
pp. 3013-3020 ◽  
Author(s):  
Hiroshi Katsuki ◽  
Yukitoshi Izumi ◽  
Charles F. Zorumski
Keyword(s):  
Synaptic Plasticity ◽  
Receptor Antagonist ◽  
Hippocampal Slices ◽  
Stimulus Frequency ◽  
Long Term Potentiation ◽  
Receptor Activation ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1

Katsuki, Hiroshi, Yukitoshi Izumi, and Charles F. Zorumski. Noradrenergic regulation of synaptic plasticity in the hippocampal CA1 region. J. Neurophysiol. 77: 3013–3020, 1997. The effects of norepinephrine (NE) and related agents on long-lasting changes in synaptic efficacy induced by several patterns of afferent stimuli were investigated in the CA1 region of rat hippocampal slices. NE (10 μM) showed little effect on the induction of long-term potentiation (LTP) triggered by theta-burst-patterned stimulation, whereas it inhibited the induction of long-term depression (LTD) triggered by 900 pulses of 1-Hz stimulation. In nontreated slices, 900 pulses of stimuli induced LTD when applied at lower frequencies (1–3 Hz), and induced LTP when applied at a higher frequency (30 Hz). NE (10 μM) caused a shift of the frequency-response relationship in the direction preferring potentiation. The effect of NE was most prominent at a stimulus frequency of 10 Hz, which induced no changes in control slices but clearly induced LTP in the presence of NE. The facilitating effect of NE on the induction of LTP by 10-Hz stimulation was blocked by theβ-adrenergic receptor antagonist timolol (50 μM), but not by the α receptor antagonist phentolamine (50 μM), and was mimicked by the β-agonist isoproterenol (0.3 μM), but not by the α1 agonist phenylephrine (10 μM). The induction of LTD by 1-Hz stimulation was prevented by isoproterenol but not by phenylephrine, indicating that the activation of β-receptors is responsible for these effects of NE. NE (10 μM) also prevented the reversal of LTP (depotentiation) by 900 pulses of 1-Hz stimulation delivered 30 min after LTP induction. In contrast to effects on naive (nonpotentiated) synapses, the effect of NE on previously potentiated synapses was only partially mimicked by isoproterenol, but fully mimicked by coapplication of phenylephrine and isoproterenol. In addition, the effect of NE was attenuated either by phentolamine or by timolol, indicating that activation of both α1 and β-receptors is required. These results show that NE plays a modulatory role in the induction of hippocampal synaptic plasticity. Althoughβ-receptor activation is essential, α1 receptor activation is also necessary in determining effects on previously potentiated synapses.

scholarly journals Different Effects of Monophasic Pulses and Biphasic Pulses Applied by a Bipolar Stimulation Electrode in the Rat Hippocampal CA1 Region

2020 ◽  
Author(s):  
Yue Yuan ◽  
Lvpiao Zheng ◽  
Zhouyan Feng ◽  
Gangsheng Yang
Keyword(s):  
Animal Experiments ◽  
Neuronal Firing ◽  
Brain Diseases ◽  
Neuron Activity ◽  
Neuronal Responses ◽  
Population Spikes ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1

Abstract Background: Deep brain stimulation (DBS) has been successfully used for treating certain brain diseases such as movement disorders. High-frequency stimulations (HFS) of charge-balanced biphasic pulses have been used in clinic DBS to minimize the risk of tissue damages caused by the electrical stimulations, while HFS sequences of monophasic pulses have been used in animal experiments to investigate DBS therapy. However, it is not clear whether HFS sequences of monophasic pulses could induce abnormal neuronal responses different from biphasic pulses. Thus, the present study investigates the differences of neuronal responses to HFS of monophasic pulses and biphasic pulses.Methods: Orthodromic-HFS (O-HFS) and antidromic-HFS (A-HFS) of the two types of pulses (with a 1-min duration) were delivered by bipolar electrodes to the Schaffer collaterals (i.e., afferent fibers) and the alveus fibers (i.e., efferent fibers) of the rat hippocampal CA1 region in-vivo, respectively. Responses of CA1 pyramidal neurons to the stimulations were recorded in the CA1 region. Single pulses of antidromic- and orthodromic-test stimuli were applied before and after HFS to evoke population spikes for evaluating the baseline and the recovery of neuronal activity. Results: Spreading depression (SD) appeared during sequences of 200 Hz monophasic O-HFS with a high incidence (4/5), but did not appear during corresponding 200 Hz biphasic O-HFS (0/6). The potential waveform of SD was accompanied by a preceding burst of population spikes, propagated slowly, silenced neuronal firing temporarily and resulted in a non-recovery of orthodromically-evoked population spikes (OPS) after the O-HFS. No SD events appeared during the O-HFS with a lower frequency of 100 Hz of monophasic and biphasic pulses (0/5 and 0/6, respectively) nor during the A-HFS of 200 Hz pulses (0/9). However, the antidromically-evoked population spikes (APS) only recovered partially after the 200 Hz A-HFS of monophasic pulses.Conclusions: The O-HFS with a high enough frequency of monophasic pulses may induce the abnormal neuron activity of SD instantaneously, which may be used as a biomarker to warn the damages caused by improper stimulations in brain tissues.

scholarly journals Chewing Prevents Stress-Induced Hippocampal LTD Formation and Anxiety-Related Behaviors: A Possible Role of the Dopaminergic System

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Yumie Ono ◽  
So Koizumi ◽  
Minoru Onozuka
Keyword(s):  
Dopaminergic System ◽  
Ventral Hippocampus ◽  
Male Rats ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Plus Maze ◽  
And Control

The present study examined the effects of chewing on stress-induced long-term depression (LTD) and anxiogenic behavior. Experiments were performed in adult male rats under three conditions: restraint stress condition, voluntary chewing condition during stress, and control condition without any treatments except handling. Chewing ameliorated LTD development in the hippocampal CA1 region. It also counteracted the stress-suppressed number of entries to the center region of the open field when they were tested immediately, 30 min, or 60 min after restraint. At the latter two poststress time periods, chewing during restraint significantly increased the number of times of open arm entries in the elevated plus maze, when compared with those without chewing. Thein vivomicrodialysis further revealed that extracellular dopamine concentration in the ventral hippocampus, which is involved in anxiety-related behavior, was significantly greater in chewing rats than in those without chewing from 30 to 105 min after stress exposure. Development of LTD and anxiolytic effects ameliorated by chewing were counteracted by administering the D1 dopamine receptor antagonist SCH23390, which suggested that chewing may activate the dopaminergic system in the ventral hippocampus to suppress stress-induced anxiogenic behavior.

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