scholarly journals Location of Sialoglycoconjugates Containing the Siaα2–3Gal and Siaα2–6Gal Groups in the Rat Hippocampus and the Effect of Aging on Their Expression

2001 ◽  
Vol 49 (10) ◽  
pp. 1311-1319 ◽  
Author(s):  
Yuji Sato ◽  
Yoshihiro Akimoto ◽  
Hayato Kawakami ◽  
Hiroshi Hirano ◽  
Tamao Endo
Keyword(s):  
Electron Microscopy ◽  
Plasma Membranes ◽  
Pyramidal Cells ◽  
Staining Intensity ◽  
Rat Hippocampus ◽  
Maackia Amurensis ◽  
Ca1 Region ◽  
Old Rats ◽  
Maackia Amurensis Lectin ◽  
Stratum Lacunosum Moleculare

The histochemical distribution of sialoglycoconjugates in the CA1 region in the hippocampus formation of 9-week-old rats and 30-month-old rats was examined using electron microscopy in combination with two lectins, Maackia amurensis lectin, specific for Siaα2–3Gal, and Sambucus sieboldiana agglutinin, specific for Siaα2–6Gal. Each lectin stained the plasma membranes of pyramidal cells, indicating that the Siaα2–3Gal and Siaα2–6Gal groups were expressed on their plasma membranes. These lectins also bound to synapses in the stratum lacunosum moleculare. The staining intensity of the lectins in the synapses in these layers was downregulated in the 30-month-old rats. These results indicated that both the Siaα2–3Gal and Siaα2–6Gal groups are expressed on these synapses and that the expression of these sialyl linkages decreases in the aged brain.

Cell-Specific Alterations in Synaptic Properties of Hippocampal CA1 Interneurons After Kainate Treatment

1998 ◽  
Vol 80 (6) ◽  
pp. 2836-2847 ◽  
Author(s):  
F. Morin ◽  
C. Beaulieu ◽  
J.-C. Lacaille
Keyword(s):  
Time Constant ◽  
Decay Time ◽  
Pyramidal Cells ◽  
Stratum Radiatum ◽  
Inhibitory Interneurons ◽  
Cell Type ◽  
Postsynaptic Currents ◽  
Ca1 Region ◽  
Hippocampal Ca1 ◽  
Stratum Lacunosum Moleculare

Morin, F., C. Beaulieu, and J.-C. Lacaille. Cell-specific alterations in synaptic properties of hippocampal CA1 interneurons after kainate treatment. J. Neurophysiol. 80: 2836–2847, 1998. Hippocampal sclerosis and hyperexcitability are neuropathological features of human temporal lobe epilepsy that are reproduced in the kainic acid (KA) model of epilepsy in rats. To assess directly the role of inhibitory interneurons in the KA model, the membrane and synaptic properties of interneurons located in 1) stratum oriens near the alveus (O/A) and 2) at the border of stratum radiatum and stratum lacunosum-moleculare (LM), as well as those of pyramidal cells, were examined with whole cell recordings in slices of control and KA-lesioned rats. In current-clamp recordings, intrinsic cell properties such as action potential amplitude and duration, amplitude of fast and medium duration afterhyperpolarizations, membrane time constant, and input resistance were generally unchanged in all cell types after KA treatment. In voltage-clamp recordings, the amplitude and conductance of pharmacologically isolated excitatory postsynaptic currents (EPSCs) were significantly reduced in LM interneurons of KA-treated animals but were not significantly changed in O/A and pyramidal cells. The rise time of EPSCs was not significantly changed in any cell type after KA treatment. In contrast, the decay time constant of EPSCs was significantly faster in O/A interneurons of KA-treated rats but was unchanged in LM and pyramidal cells. The amplitude and conductance of pharmacologically isolated γ-aminobutyric acid-A (GABAA) inhibitory postsynaptic currents (IPSCs) were not significantly changed in any cell type of KA-treated rats. The rise time and decay time constant of GABAA IPSCs were significantly faster in pyramidal cells of KA-treated rats but were not significantly changed in O/A and LM interneurons. These results suggest that complex alterations in synaptic currents occur in specific subpopulations of inhibitory interneurons in the CA1 region after KA lesions. A reduction of evoked excitatory drive onto inhibitory cells located at the border of stratum radiatum and stratum lacunosum-moleculare may contribute to disinhibition and polysynaptic epileptiform activity in the CA1 region. Compensatory changes, involving excitatory synaptic transmission on other interneuron subtypes and inhibitory synaptic transmission on pyramidal cells, may also take place and contribute to the residual, functional monosynaptic inhibition observed in principal cells after KA treatment.

Serotonin blocks the facilitatory action of muscarinic and nicotinic agents in the hippocampus in vivo

1989 ◽  
Vol 67 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Y. Hong ◽  
K. Krnjević
Keyword(s):  
Inhibitory Action ◽  
Pyramidal Cells ◽  
Inhibitory Effect ◽  
Population Spike ◽  
Rat Hippocampus ◽  
Population Spikes ◽  
Ca1 Region ◽  
Facilitatory Action ◽  
Hippocampal Pyramidal Cells

The inhibitory effect of serotonin, released iontophoretically, on acetylcholine-induced facilitation of population spikes evoked by fimbria–commissural stimulation was studied in the CA1 region of rat hippocampus in vivo. After serotonin was applied for 2.6 ± 0.8 min, acetylcholine's action was inhibited in 39 cases out of 57 (68.4%), by 68.9 ± 23.1%, irrespective of whether serotonin alone increased or reduced the population spike. Spiperone, used as a 5-hydroxytryptamine1A (5-HT1A) antagonist, suppressed the inhibitory action of serotonin in 14 of 21 tests. Serotonin had similar effects on population spike facilitations induced by acetyl-β-methylcholine and dimethylphenylpiperazinium. Thus serotonin, probably acting on 5-HT1A receptors, blocks effectively but indiscriminately all cholinergic facilitations, whether mediated by nicotinic or muscarinic receptors.Key words: serotonin, cholinergic facilitation, hippocampal pyramidal cells, spiperone, muscarinic and nicotinic actions.

scholarly journals Stratum Lacunosum-moleculare Interneurons of the Hippocampus Coordinate Memory Encoding and Retrieval

2021 ◽  
Author(s):  
Jun Guo ◽  
Heankel Cantu Oliveros ◽  
So Jung Oh ◽  
Bo Liang ◽  
Ying Li ◽  
...  
Keyword(s):  
Pyramidal Cells ◽  
Brain Regions ◽  
Cellular Level ◽  
Memory Encoding ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Stratum Lacunosum Moleculare ◽  
Encoding And Retrieval

Encoding and retrieval of memory are two processes serving distinct biological purposes but operating in highly overlapping brain circuits. It is unclear how the two processes are coordinated in the same brain regions, especially in the hippocampal CA1 region where the two processes converge at the cellular level. Here we find that the neuron-derived neurotrophic factor (NDNF)-positive interneurons at stratum lacunosum-moleculare (SLM) in CA1 play opposite roles in memory encoding and retrieval. These interneurons show high activities in learning and low activities in recall. Increasing their activity facilitates learning but impairs recall. They inhibit the entorhinal- but dis-inhibit the CA3- inputs to CA1 pyramidal cells and thereby either suppress or elevate CA1 pyramidal cells′ activity depending on animal′s behavioral states. Thus, by coordinating entorhinal- and CA3- dual inputs to CA1, these SLM interneurons are key to switching the hippocampus between encoding and retrieval modes.

Changes in inhibitory neurotransmission in the CA1 region and dentate gyrus in a chronic model of temporal lobe epilepsy

1995 ◽  
Vol 74 (2) ◽  
pp. 829-840 ◽  
Author(s):  
P. S. Mangan ◽  
D. A. Rempe ◽  
E. W. Lothman
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Dentate Gyrus ◽  
Temporal Lobe ◽  
Granule Cells ◽  
Pyramidal Cells ◽  
Stratum Radiatum ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Stratum Lacunosum Moleculare ◽  
Reversal Potentials

1. In this report we compare changes in inhibitory neurotransmission within the CA1 region and the dentate gyrus (DG) in a model of chronic temporal lobe epilepsy (TLE). Extracellular and intracellular recordings were obtained in combined hippocampal-parahippocampal slices > or = 1 mo after a period of self-sustaining limbic status epilepticus (SSLSE) induced by continuous hippocampal stimulation. 2. Polysynaptic inhibitory postsynaptic potentials (IPSPs) were induced by positioning electrodes to activate specific afferent pathways and evoking responses in the absence of glutamate receptor antagonists [D(-)-2-amino-5-phosphonovaleric acid (APV) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)]. Polysynaptic IPSPs were evoked in CA1 pyramidal cells from electrodes positioned in stratum radiatum and in stratum lacunosum/moleculare. Polysynaptic IPSPs were evoked in DG granule cells from electrodes positioned over the perforant path located in the subiculum. Monosynaptic IPSPs were induced by positioning electrodes within 200 microns of the intracellular recording electrode (near site stimulation) and stimulating in the presence of APV and CNQX to block ionotropic glutamate receptors. Monosynaptic IPSPs were evoked in CA1 pyramidal cells with electrodes positioned in the stratum lacunosum/moleculare and stratum pyramidale. Monosynaptic IPSPs were evoked in DG granule cells with electrodes positioned in the stratum moleculare. 3. Population spike (PS) amplitudes were employed to assure that a full range of stimulus strengths, from subthreshold for action potentials to an intensity giving maximal-amplitude PSs, was used to elicit polysynaptic IPSPs in CA1 pyramidal cells in both post-SSLSE and control slices. In control tissue, polysynaptic IPSPs were biphasic, composed of early and late events. In post-SSLSE tissue, polysynaptic IPSPs were markedly diminished. The diminution of polysynaptic IPSPs was detected at all levels of stimulus intensity. Both early IPSPs [mediated by gamma-aminobutyric acid-A (GABAA) receptors] and late IPSPs (mediated by GABAB receptors) were diminished. Polysynaptic IPSPs were diminished with both stratum radiatum and with stratum lacunosum/moleculare stimulation. 4. Reversal potentials for either polysynaptic early or polysynaptic late IPSPs evoked in CA1 pyramidal cells by stratum radiatum stimulation were not different in slices from post-SSLSE animals as compared with control animals. Likewise, reversal potentials for either polysynaptic early or polysynaptic late IPSPs evoked by stratum lacunosum/moleculare stimulation did not differ in the two groups. These findings excluded changes in driving force as an explanation for the diminished amplitude of IPSPs in CA1 pyramidal cells in the post-SSLSE model.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Distribution of Sialoglycoconjugates in the Rat Cerebellum and Its Change with Aging

2002 ◽  
Vol 50 (9) ◽  
pp. 1179-1186 ◽  
Author(s):  
Tasuku Sasaki ◽  
Yoshihiro Akimoto ◽  
Yuji Sato ◽  
Hayato Kawakami ◽  
Hiroshi Hirano ◽  
...  
Keyword(s):  
Granular Layer ◽  
Molecular Layer ◽  
Expression Patterns ◽  
Aged Rats ◽  
Adult Rats ◽  
Rat Cerebellum ◽  
Maackia Amurensis ◽  
Old Rats ◽  
Maackia Amurensis Lectin ◽  
Granular Layers

We examined the distribution of sialoglycoconjugates in the cerebellum of 9-week-old and 30-month-old rats using light microscopy and electron microscopy in combination with two lectins, Maackia amurensis lectin (MAL) for Siaα2-3Gal and Sambucus sieboldiana agglutinin (SSA) for Siaα2-6Gal. Each lectin showed characteristic staining patterns. In young adult rats, MAL stained a strongly granular layer, a weakly molecular layer, and the medullary lamina, while SSA more strongly stained the medullary lamina than the molecular and granular layers. After aging, different staining patterns were obtained. Intense SSA reactivity was observed in the granular layer and intense MAL reactivity was observed in the medullary lamina of the aged groups. The reactivity of Purkinje cells with MAL was downregulated in the aged rats. These results indicated that Siaα2-3Gal and Siaα2-6Gal were expressed in distinct regions of the rat cerebellum and that their expression patterns changed in the aged brain.

scholarly journals Stratum Lacunosum-moleculare Interneurons of the Hippocampus Coordinate Memory Encoding and Retrieval

2021 ◽  
Author(s):  
Jun Guo ◽  
Heankel Oliveros ◽  
So Jung Oh ◽  
Bo Liang ◽  
Ying Li ◽  
...  
Keyword(s):  
Pyramidal Cells ◽  
Brain Regions ◽  
Cellular Level ◽  
Memory Encoding ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Stratum Lacunosum Moleculare ◽  
Encoding And Retrieval

Abstract Encoding and retrieval of memory are two processes serving distinct biological purposes but operating in highly overlapping brain circuits. It is unclear how the two processes are coordinated in the same brain regions, especially in the hippocampal CA1 region where the two processes converge at the cellular level. Here we find that the neuron-derived neurotrophic factor (NDNF)-positive interneurons at stratum lacunosum-moleculare (SLM) in CA1 play opposite roles in memory encoding and retrieval. These interneurons show high activities in learning and low activities in recall. Increasing their activity facilitates learning but impairs recall. They inhibit the entorhinal- but dis-inhibit the CA3- inputs to CA1 pyramidal cells and thereby either suppress or elevate CA1 pyramidal cells’ activity depending on animal’s behavioral states. Thus, by coordinating entorhinal- and CA3- dual inputs to CA1, these SLM interneurons are key to switching the hippocampus between encoding and retrieval modes.

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