Estrone-3-sulfate acts at a postsynaptic site on rat CA1 pyramidal cells

Abstract The entorhinal cortex alvear pathway is a major excitatory input to hippocampal CA1, yet nothing is known about its physiological impact. We investigated the alvear pathway projection and innervation of neurons in CA1 using optogenetics and whole cell patch clamp methods in transgenic mouse brain slices. Using this approach, we show that the medial entorhinal cortical alvear inputs onto CA1 pyramidal cells (PCs) and interneurons with cell bodies located in stratum oriens were monosynaptic, had low release probability, and were mediated by glutamate receptors. Optogenetic theta burst stimulation was unable to elicit suprathreshold activation of CA1 PCs but was capable of activating CA1 interneurons. However, different subtypes of interneurons were not equally affected. Higher burst action potential frequencies were observed in parvalbumin-expressing interneurons relative to vasoactive-intestinal peptide-expressing or a subset of oriens lacunosum-moleculare (O-LM) interneurons. Furthermore, alvear excitatory synaptic responses were observed in greater than 70% of PV and VIP interneurons and less than 20% of O-LM cells. Finally, greater than 50% of theta burst-driven inhibitory postsynaptic current amplitudes in CA1 PCs were inhibited by optogenetic suppression of PV interneurons. Therefore, our data suggest that the alvear pathway primarily affects hippocampal CA1 function through feedforward inhibition of select interneuron subtypes.

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Level of Arousal During the Small Irregular Activity State in the Rat Hippocampal EEG

Journal of Neurophysiology ◽

10.1152/jn.01082.2003 ◽

2004 ◽

Vol 91 (6) ◽

pp. 2649-2657 ◽

Cited By ~ 15

Author(s):

Beata Jarosiewicz ◽

William E. Skaggs

Keyword(s):

Slow Wave Sleep ◽

Power Spectra ◽

Pyramidal Cells ◽

Auditory Stimuli ◽

Sleep State ◽

Population Activity ◽

Ca1 Pyramidal Cells ◽

Emg Amplitude ◽

Current Location ◽

Activity State

The sleeping rat cycles between two well-characterized hippocampal physiological states, large irregular activity (LIA) during slow-wave sleep (SWS) and theta activity during rapid-eye-movement sleep (REM). A third, less well-characterized electroencephalographic (EEG) state, termed “small irregular activity” (SIA), has been reported to occur when an animal is startled out of sleep without moving and during active waking when it abruptly freezes. We recently found that the hippocampal population activity of a spontaneous sleep state whose EEG resembles SIA reflects the rat's current location in space, suggesting that it is also a state of heightened arousal. To test whether this spontaneous SIA state corresponds to the SIA state reported in the literature and to compare the level of arousal during SIA to the other well-characterized physiological states, we recorded unit activity from ensembles of hippocampal CA1 pyramidal cells, EEG from the hippocampus and the neocortex, and electromyography (EMG) from the dorsal neck musculature in rats presented with auditory stimuli while foraging for randomly scattered food pellets and while sleeping. Auditory stimuli presented during sleep reliably induced SIA episodes very similar to spontaneous SIA in hippocampal and neocortical EEG amplitudes and power spectra, EMG amplitude, and CA1 population activity. Both spontaneous and elicited SIA exhibited neocortical desynchronization, and both had EMG amplitude comparable to that of waking LIA. We conclude based on this and other evidence that spontaneous SIA and elicited SIA correspond to a single state and that the level of arousal in SIA is higher than in the well-characterized sleep states but lower than the active theta state.

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Hyperpolarizing synaptic potentials evoked in CA1 pyramidal cells by glutamate stimulation of interneurons from the oriens/alveus border of rat hippocampal slices. I. Electrophysiological response properties

Hippocampus ◽

10.1002/hipo.450030308 ◽

1993 ◽

Vol 3 (3) ◽

pp. 331-344 ◽

Cited By ~ 12

Author(s):

Donald D. Samulack ◽

Sylvain Williams ◽

Jean-Claude Lacaille

Keyword(s):

Hippocampal Slices ◽

Pyramidal Cells ◽

Electrophysiological Response ◽

Response Properties ◽

Ca1 Pyramidal Cells ◽

Synaptic Potentials ◽

Stimulation Of

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Selective Induction of LTP and LTD by Postsynaptic [Ca2+]i Elevation

Journal of Neurophysiology ◽

10.1152/jn.1999.81.2.781 ◽

1999 ◽

Vol 81 (2) ◽

pp. 781-787 ◽

Cited By ~ 311

Author(s):

Shao-Nian Yang ◽

Yun-Gui Tang ◽

Robert S. Zucker

Keyword(s):

Calcium Concentration ◽

Pyramidal Cells ◽

Long Term Potentiation ◽

Biological Information ◽

Synaptic Modulation ◽

Ca1 Pyramidal Cells ◽

Caged Calcium ◽

Term Potentiation ◽

Calcium Compound

Selective Induction of LTP and LTD by Postsynaptic [Ca2+]i Elevation. Long-term potentiation (LTP) and long-term depression (LTD), two prominent forms of synaptic plasticity at glutamatergic afferents to CA1 hippocampal pyramidal cells, are both triggered by the elevation of postsynaptic intracellular calcium concentration ([Ca2+]i). To understand how one signaling molecule can be responsible for triggering two opposing forms of synaptic modulation, different postsynaptic [Ca2+]i elevation patterns were generated by a new caged calcium compound nitrophenyl-ethylene glycol-bis(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid in CA1 pyramidal cells. We found that specific patterns of [Ca2+]i elevation selectively activate LTP or LTD. In particular, only LTP was triggered by a brief increase of [Ca2+]i with relatively high magnitude, which mimics the [Ca2+]i rise during electrical stimulation typically used to induce LTP. In contrast, a prolonged modest rise of [Ca2+]i reliably induced LTD. An important implication of the results is that both the amplitude and the duration of an intracellular chemical signal can carry significant biological information.

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