Endogenously synthesized levels of neurosteroids constitutively enhance normal excitatory synaptic transmission and synaptic plasticity in the rat dentate gyrus

cAMP-dependent protein kinase (PKA) and protein kinase C (PKC) are two major modulators of synaptic transmission in the CNS but little is known about how they affect synaptic transmission in the human CNS. In this study, we used forskolin, a PKA activator, and phorbol ester, a PKC activator, to examine the effects of these kinases on synaptic transmission in granule cells of the dentate gyrus in human hippocampal slices using whole-cell recording methods. We found that both forskolin and phorbol ester increased the frequency of spontaneous and miniature excitatory postsynaptic currents (sEPSCs and mEPSCs) but left the amplitude unaffected. Inactive forskolin and phorbol ester had no effect on sEPSCs in human dentate granule cells. Prior application of forskolin occluded the effects of phorbol ester on mEPSC frequency. Tetanic stimulation applied to the perforant path induced short-term depression in dentate gyrus granule cells. Both forskolin and phorbol ester significantly enhanced this short-term depression. Taken together, these results demonstrate that PKA and PKC are involved in up-regulation of excitatory synaptic transmission in human dentate granule cells, primarily by presynaptic mechanisms. In addition, the occlusion experiments suggest that the two kinases may share a common signal pathway.

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BACE1 Is Necessary for Experience-Dependent Homeostatic Synaptic Plasticity in Visual Cortex

Neural Plasticity ◽

10.1155/2014/128631 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 11

Author(s):

Emily Petrus ◽

Hey-Kyoung Lee

Keyword(s):

Synaptic Plasticity ◽

Visual Cortex ◽

Synaptic Transmission ◽

Sensory Experience ◽

Synaptic Function ◽

Excitatory Synaptic Transmission ◽

Early Gene ◽

Dependent Manner ◽

Homeostatic Synaptic Plasticity ◽

Activity Dependent

Alzheimer’s disease (AD) is the most common form of age-related dementia, which is thought to result from overproduction and/or reduced clearance of amyloid-beta (Aβ) peptides. Studies over the past few decades suggest that Aβis produced in an activity-dependent manner and has physiological relevance to normal brain functions. Similarly, physiological functions forβ- andγ-secretases, the two key enzymes that produce Aβby sequentially processing the amyloid precursor protein (APP), have been discovered over recent years. In particular, activity-dependent production of Aβhas been suggested to play a role in homeostatic regulation of excitatory synaptic function. There is accumulating evidence that activity-dependent immediate early gene Arc is an activity “sensor,” which acts upstream of Aβproduction and triggers AMPA receptor endocytosis to homeostatically downregulate the strength of excitatory synaptic transmission. We previously reported that Arc is critical for sensory experience-dependent homeostatic reduction of excitatory synaptic transmission in the superficial layers of visual cortex. Here we demonstrate that mice lacking the major neuronalβ-secretase, BACE1, exhibit a similar phenotype: stronger basal excitatory synaptic transmission and failure to adapt to changes in visual experience. Our results indicate that BACE1 plays an essential role in sensory experience-dependent homeostatic synaptic plasticity in the neocortex.

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Morphine augments excitatory synaptic transmission in the dentate gyrus through GABAergic disinhibition

Neuroscience Research ◽

10.1016/s0168-0102(00)00177-2 ◽

2000 ◽

Vol 38 (4) ◽

pp. 357-363 ◽

Cited By ~ 26

Author(s):

Tatsuhiro Akaishi ◽

Hiroshi Saito ◽

Yoshihisa Ito ◽

Kumiko Ishige ◽

Yuji Ikegaya

Keyword(s):

Synaptic Transmission ◽

Dentate Gyrus ◽

Excitatory Synaptic Transmission

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Facilitatory effects of subanesthetic sevoflurane on excitatory synaptic transmission and synaptic plasticity in the mouse hippocampal CA1 area

Brain Research ◽

10.1016/j.brainres.2007.12.035 ◽

2008 ◽

Vol 1197 ◽

pp. 32-39 ◽

Cited By ~ 12

Author(s):

Toshiki Otsubo ◽

Masao Maekawa ◽

Toshiaki Nagai ◽

Hideaki Sakio ◽

Yuuichi Hori

Keyword(s):

Synaptic Plasticity ◽

Synaptic Transmission ◽

Excitatory Synaptic Transmission ◽

Hippocampal Ca1 ◽

Hippocampal Ca1 Area ◽

Ca1 Area

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Neuroligin-1 regulates excitatory synaptic transmission, LTP and EPSP-spike coupling in the dentate gyrus in vivo

Brain Structure and Function ◽

10.1007/s00429-013-0636-1 ◽

2013 ◽

Vol 220 (1) ◽

pp. 47-58 ◽

Cited By ~ 36

Author(s):

Peter Jedlicka ◽

Matej Vnencak ◽

Dilja D. Krueger ◽

Tassilo Jungenitz ◽

Nils Brose ◽

...

Keyword(s):

Synaptic Transmission ◽

Dentate Gyrus ◽

Excitatory Synaptic Transmission

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

Journal of Neurophysiology ◽

10.1152/jn.1995.74.5.2201 ◽

1995 ◽

Vol 74 (5) ◽

pp. 2201-2203 ◽

Cited By ~ 22

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.

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