scholarly journals Structural and functional characterization of dendritic arbors and GABAergic synaptic inputs on interneurons and principal cells in the rat basolateral amygdala

2015 ◽  
Vol 114 (2) ◽  
pp. 942-957 ◽  
Author(s):  
Paul M. Klenowski ◽  
Matthew J. Fogarty ◽  
Arnauld Belmer ◽  
Peter G. Noakes ◽  
Mark C. Bellingham ◽  
...  
Keyword(s):  
Basolateral Amygdala ◽  
Morphological Characteristics ◽  
Cell Types ◽  
Network Activity ◽  
Emotional States ◽  
Inhibitory Postsynaptic Currents ◽  
Principal Cells ◽  
Postsynaptic Currents ◽  
Gabaergic Synapses ◽  
Local Circuitry

The basolateral amygdala (BLA) is a complex brain region associated with processing emotional states, such as fear, anxiety, and stress. Some aspects of these emotional states are driven by the network activity of synaptic connections, derived from both local circuitry and projections to the BLA from other regions. Although the synaptic physiology and general morphological characteristics are known for many individual cell types within the BLA, the combination of morphological, electrophysiological, and distribution of neurochemical GABAergic synapses in a three-dimensional neuronal arbor has not been reported for single neurons from this region. The aim of this study was to assess differences in morphological characteristics of BLA principal cells and interneurons, quantify the distribution of GABAergic neurochemical synapses within the entire neuronal arbor of each cell type, and determine whether GABAergic synaptic density correlates with electrophysiological recordings of inhibitory postsynaptic currents. We show that BLA principal neurons form complex dendritic arborizations, with proximal dendrites having fewer spines but higher densities of neurochemical GABAergic synapses compared with distal dendrites. Furthermore, we found that BLA interneurons exhibited reduced dendritic arbor lengths and spine densities but had significantly higher densities of putative GABAergic synapses compared with principal cells, which was correlated with an increased frequency of spontaneous inhibitory postsynaptic currents. The quantification of GABAergic connectivity, in combination with morphological and electrophysiological measurements of the BLA cell types, is the first step toward a greater understanding of how fear and stress lead to changes in morphology, local connectivity, and/or synaptic reorganization of the BLA.

Amino acid-mediated regulation of spontaneous synaptic activity patterns in the rat basolateral amygdala

1996 ◽  
Vol 76 (3) ◽  
pp. 1958-1967 ◽  
Author(s):  
B. N. Smith ◽  
F. E. Dudek
Keyword(s):  
Receptor Antagonist ◽  
Time Constant ◽  
Decay Time ◽  
Basolateral Amygdala ◽  
Activity Patterns ◽  
Nmda Receptor Antagonist ◽  
Synaptic Activity ◽  
Gamma Aminobutyric Acid ◽  
Postsynaptic Currents ◽  
Local Circuitry

1. Spontaneous postsynaptic currents (PSCs) were examined in the basolateral amygdala using whole cell patch-clamp recordings in coronal slices (400 microns) from young rats (postnatal day 6-25). In most cells, Cs+ was used in the electrode to block putative voltage-activated K(+)-currents. Both inward and outward spontaneous PSCs were examined. 2. The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor antagonist, 6,7-nitroquinoxaline-2,3-dione (DNQX) blocked all inward PSCs, which reversed near 0 mV. They therefore were considered to be glutamate-mediated excitatory postsynaptic currents (EPSCs). Averaged EPSCs had a rapid 10-90% rise time (1.0 +/- 0.04 ms; mean +/- SD) and monoexponential decay (tau = 3.6 +/- 0.18 ms) at potentials negative to about -50 mV. Above this potential, a second, slower time constant (tau 1 = 41 +/- 4.5 ms at -30 mV), accounting for 10-30% of the total EPSC amplitude was resolved in 8 of 10 cells examined. The slower decay time constant was sensitive to the N-methyl-D-aspartate (NMDA)-receptor antagonist, DL-2-amino-5-phosphonovaleric acid (AP5) and therefore probably was due to activation of NMDA receptors. 3. The gamma-aminobutyric acid-A (GABAA) antagonist, bicuculline, blocked all outward PSCs, which reversed near -70 mV. They therefore were considered to be GABA-mediated inhibitory postsynaptic currents (IPSCs). Averaged IPSCs displayed rapid 10-90% rise times (1.0 +/- 0.03 ms) and monoexponential decay time constants (tau = 5.16 +/- 0.14 ms). 4. Tetrodotoxin (TTX) reduced the frequency of synaptic activity and eliminated the largest PSCs, thus reducing slightly the mean EPSC and IPSC amplitude. Most cells received bursts of spontaneous IPSCs and/or EPSCs (30-68 Hz lasting 0.5-6 s), which were also TTX sensitive. The TTX data suggest that the somata of the cells responsible for the largest PSCs and the PSC bursts were contained within the slice. 5. In addition to blocking EPSCs, DNQX blocked the bursts of IPSCs, but not all individual IPSCs. DNQX had similar effects as TTX on the bursts and frequency of the IPSCs. 6. Bicuculline enhanced spontaneous EPSC frequency (231 +/- 90%). Much of this increase was due to an increase in the bursts of EPSCs. 7. Neurons in the basolateral amygdala therefore appear to receive both excitatory (glutamatergic) and inhibitory (GABAergic) synaptic input from local neurons. The activity of the neurons responsible for these inputs are themselves largely regulated by glutamatergic and GABAergic inputs. The relevance of this local circuitry to seizures and epilepsy is discussed briefly.

Effect of Adrenalectomy on Miniature Inhibitory Postsynaptic Currents in the Paraventricular Nucleus of the Hypothalamus

2003 ◽  
Vol 89 (1) ◽  
pp. 237-245 ◽  
Author(s):  
J. M. Verkuyl ◽  
M. Joëls
Keyword(s):  
Paraventricular Nucleus ◽  
Negative Feedback ◽  
Network Activity ◽  
Inhibitory Input ◽  
Lateral Part ◽  
Compensatory Mechanism ◽  
Magnocellular Neurons ◽  
Inhibitory Postsynaptic Currents ◽  
Postsynaptic Currents ◽  
Parvocellular Neurons

Within the rat paraventricular nucleus of the hypothalamus two types of neurons have been distinguished based on morphological appearance, i.e., parvocellular and magnocellular neurons. The parvocellular neurons play a key role in regulating the activity of the hypothalamo–pituitary–adrenal axis, which is activated, e.g., after stress exposure. These neurons receive humoral negative feedback via the adrenal hormone corticosterone but also neuronal inhibitory input, either directly or transsynaptically relayed via GABAergic interneurons. In the present study we examined to what extent the neuronal GABAergic input is influenced by the humoral signal. To this end, miniature inhibitory postsynaptic currents (mIPSCs) were recorded in parvo- and magnocellular neurons of adrenalectomized rats, which lack corticosterone, and in sham-operated controls. Under visual control neurons in coronal slices containing the paraventricular nucleus were designated as putative parvocellular or magnocellular neurons: the former were located in the medial part of the nucleus and displayed a small fusiform soma; the latter were mostly located in the lateral part and were recognized by their large round soma. Compared with putative magnocellular neurons, parvocellular neurons generally exhibited a lower membrane capacitance, lower mIPSC frequency, and smaller mIPSC amplitude. Following adrenalectomy, the mIPSC frequency was significantly enhanced in parvo- but not magnocellular neurons. Other properties of the cells were not affected. In a second series of experiments we examined whether the increase in mIPSC frequency was due to the absence of corticosterone or caused by other effects related to adrenalectomy. The data support the former explanation since implantation of a corticosterone releasing pellet after adrenalectomy fully prevented the change in mIPSC frequency. We conclude that, in the absence of humoral negative feedback, local GABAergic input of parvocellular neurons in the paraventricular nucleus is enhanced. This may provide a compensatory mechanism necessary for maintaining controllable network activity.

scholarly journals Plasticity of spontaneous excitatory and inhibitory synaptic activity in morphologically defined vestibular nuclei neurons during early vestibular compensation

2012 ◽  
Vol 107 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Mei Shao ◽  
June C. Hirsch ◽  
Kenna D. Peusner
Keyword(s):  
Charge Transfer ◽  
Brain Slices ◽  
Vestibular Nuclei ◽  
Synaptic Activity ◽  
Vestibular Compensation ◽  
Early Recovery ◽  
Inhibitory Postsynaptic Currents ◽  
Principal Cells ◽  
Postsynaptic Currents ◽  
Lesion Side

After unilateral peripheral vestibular lesions, the brain plasticity underlying early recovery from the static symptoms is not fully understood. Principal cells of the chick tangential nucleus offer a subset of morphologically defined vestibular nuclei neurons to study functional changes after vestibular lesions. Chickens show posture and balance deficits immediately after unilateral vestibular ganglionectomy (UVG), but by 3 days most subjects begin to recover, although some remain uncompensated. With the use of whole cell voltage-clamp, spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs) and miniature excitatory and inhibitory postsynaptic currents (mEPSCs and mIPSCs) were recorded from principal cells in brain slices 1 and 3 days after UVG. One day after UVG, sEPSC frequency increased on the lesion side and remained elevated at 3 days in uncompensated chickens only. Also by 3 days, sIPSC frequency increased on the lesion side in all operated chickens due to major increases in GABAergic events. Significant change also occurred in decay time of the events. To determine whether fluctuations in frequency and kinetics influenced overall excitatory or inhibitory synaptic drive, synaptic charge transfer was calculated. Principal cells showed significant increase in excitatory synaptic charge transfer only on the lesion side of uncompensated chickens. Thus compensation continues when synaptic charge transfer is in balance bilaterally. Furthermore, excessive excitatory drive in principal cells on the lesion side may prevent vestibular compensation. Altogether, this work is important for it defines the time course and excitatory and inhibitory nature of changing spontaneous synaptic inputs to a morphologically defined subset of vestibular nuclei neurons during critical early stages of recovery after UVG.

scholarly journals Serotonergic control of GABAergic inhibition in the lateral amygdala

2020 ◽  
Vol 123 (2) ◽  
pp. 670-681
Author(s):  
Ryo Yamamoto ◽  
Takafumi Furuyama ◽  
Tokio Sugai ◽  
Munenori Ono ◽  
Denis Pare ◽  
...  
Keyword(s):  
Presynaptic Inhibition ◽  
Time Course ◽  
Gaba Release ◽  
Fast Time ◽  
Synaptic Inhibition ◽  
Lateral Amygdala ◽  
Inhibitory Postsynaptic Currents ◽  
Postsynaptic Currents ◽  
Gabaergic Synapses

Much evidence implicates the serotonergic regulation of the amygdala in anxiety. Thus the present study was undertaken to characterize the influence of serotonin (5-HT) on principal neurons (PNs) of the rat lateral amygdala (LA), using whole cell recordings in vitro. Because inhibition is a major determinant of PN activity, we focused on the control of GABAergic transmission by 5-HT. IPSCs were elicited by local electrical stimulation of LA in the presence of glutamate receptor antagonists. We found that 5-HT reduces GABAA inhibitory postsynaptic currents (IPSCs) via presynaptic 5-HT1B receptors. While the presynaptic inhibition of GABA release also attenuated GABAB currents, this effect was less pronounced than for GABAA currents because 5-HT also induced a competing postsynaptic enhancement of GABAB currents. That is, GABAB currents elicited by pressure application of GABA or baclofen were enhanced by 5-HT. In addition, we obtained evidence suggesting that 5-HT differentially regulates distinct subsets of GABAergic synapses. Indeed, GABAA IPSCs were comprised of two components: a relatively 5-HT-insensitive IPSC that had a fast time course and a 5-HT-sensitive component that had a slower time course. Because the relative contribution of these two components varied depending on whether neurons were recorded at proximity versus at a distance from the stimulating electrodes, we speculate that distinct subtypes of local-circuit cells contribute the two contingents of GABAergic synapses. Overall, our results indicate that 5-HT is a potent regulator of synaptic inhibition in LA. NEW & NOTEWORTHY We report that 5-HT, acting via presynaptic 5-HT1B receptors, attenuates GABAA IPSCs by reducing GABA release in the lateral amygdala (LA). In parallel, 5-HT enhances GABAB currents postsynaptically, such that GABAB inhibitory postsynaptic currents (IPSCs) are relatively preserved from the presynaptic inhibition of GABA release. We also found that the time course of 5-HT-sensitive and -insensitive GABAA IPSCs differ. Together, these results indicate that 5-HT is a potent regulator of synaptic inhibition in LA.

scholarly journals Depressed GABA and glutamate synaptic signaling by 5-HT1A receptors in the nucleus tractus solitarii and their role in cardiorespiratory function

2014 ◽  
Vol 111 (12) ◽  
pp. 2493-2504 ◽  
Author(s):  
Tim D. Ostrowski ◽  
Daniela Ostrowski ◽  
Eileen M. Hasser ◽  
David D. Kline
Keyword(s):  
Nucleus Tractus Solitarii ◽  
Network Activity ◽  
Cardiorespiratory System ◽  
Excitatory Postsynaptic Currents ◽  
Inhibitory Postsynaptic Currents ◽  
Postsynaptic Currents ◽  
Cardiorespiratory Function ◽  
Synaptic Parameters ◽  
Brain Stem Slices

Serotonin (5-HT), and its 5-HT1A receptor (5-HT1AR) subtype, is a powerful modulator of the cardiorespiratory system and its sensory reflexes. The nucleus tractus solitarii (nTS) serves as the first central station for visceral afferent integration and is critical for cardiorespiratory reflex responses. However, the physiological and synaptic role of 5-HT1ARs in the nTS is relatively unknown. In the present study, we examined the distribution and modulation of 5-HT1ARs on cardiorespiratory and synaptic parameters in the nTS. 5-HT1ARs were widely distributed to cell bodies within the nTS but not synaptic terminals. In anesthetized rats, activation of 5-HT1ARs by microinjection of the 5-HT1AR agonist 8-OH-DPAT into the caudal nTS decreased minute phrenic neural activity via a reduction in phrenic amplitude. In brain stem slices, 8-OH-DPAT decreased the amplitude of glutamatergic tractus solitarii-evoked excitatory postsynaptic currents, and reduced overall spontaneous excitatory nTS network activity. These effects persisted in the presence of GABAA receptor blockade and were antagonized by coapplication of 5-HT1AR blocker WAY-100135. 5-HT1AR blockade alone had no effect on tractus solitarii-evoked excitatory postsynaptic currents, but increased excitatory network activity. On the other hand, GABAergic nTS-evoked inhibitory postsynaptic currents did not change by activation of the 5-HT1ARs, but spontaneous inhibitory nTS network activity decreased. Blocking 5-HT1ARs tended to increase nTS-evoked inhibitory postsynaptic currents and inhibitory network activity. Taken together, 5-HT1ARs in the caudal nTS decrease breathing, likely via attenuation of afferent transmission, as well as overall nTS network activity.

Development of Excitatory Circuitry in the Hippocampus

1998 ◽  
Vol 79 (4) ◽  
pp. 2013-2024 ◽  
Author(s):  
Albert Y. Hsia ◽  
Robert C. Malenka ◽  
Roger A. Nicoll
Keyword(s):  
Synaptic Transmission ◽  
Action Potentials ◽  
Pyramidal Cells ◽  
Excitatory Synaptic Transmission ◽  
Developmental Strategy ◽  
Excitatory Postsynaptic Currents ◽  
Postsynaptic Currents ◽  
Quantal Size ◽  
Physiological Approach ◽  
Local Circuitry

Hsia, Albert Y., Robert C. Malenka, and Roger A. Nicoll. Development of excitatory circuitry in the hippocampus. J. Neurophysiol. 79: 2013–2024, 1998. Assessing the development of local circuitry in the hippocampus has relied primarily on anatomic studies. Here we take a physiological approach, to directly evaluate the means by which the mature state of connectivity between CA3 and CA1 hippocampal pyramidal cells is established. Using a technique of comparing miniature excitatory postsynaptic currents (mEPSCs) to EPSCs in response to spontaneously occurring action potentials in CA3 cells, we found that from neonatal to adult ages, functional synapses are created and serve to increase the degree of connectivity between CA3-CA1 cell pairs. Neither the probability of release nor mean quantal size was found to change significantly with age. However, the variability of quantal events decreases substantially as synapses mature. Thus in the hippocampus the developmental strategy for enhancing excitatory synaptic transmission does not appear to involve an increase in the efficacy at individual synapses, but rather an increase in the connectivity between cell pairs.

GABAA Receptor β3 Subunit Deletion Decreases α2/3 Subunits and IPSC Duration

2003 ◽  
Vol 89 (1) ◽  
pp. 128-134 ◽  
Author(s):  
Epolia Ramadan ◽  
Zhanyan Fu ◽  
Gabriele Losi ◽  
Gregg E. Homanics ◽  
Joseph H. Neale ◽  
...  
Keyword(s):  
Gabaa Receptor ◽  
Cortical Neurons ◽  
Behavioral Deficits ◽  
Inhibitory Postsynaptic Currents ◽  
Postsynaptic Currents ◽  
Surface Staining ◽  
Α1 Subunit

Deletion of the β3 subunit of the GABAA receptor produces severe behavioral deficits and epilepsy. GABAA receptor-mediated miniature inhibitory postsynaptic currents (mIPSCs) in cortical neurons in cultures from β3 −/− mice were significantly faster than those in β3 +/+ mice and were more prolonged by zolpidem. Surface staining revealed that the number of β2/3, α2, and α3 (but not of α1) subunit-expressing neurons and the intensity of subunit clusters were significantly reduced in β3 −/− mice. Transfection of β3 −/− neurons with β3 cDNA restored β2/3, α2, and α3 subunits immunostaining and slowed mIPSCs decay. We show that the deletion of the β3 subunit causes the loss of a subset of GABAA receptors with α2 and α3 subunits while leaving a receptor population containing predominantly α1 subunit with fast spontaneous IPSC decay and increased zolpidem sensitivity.

scholarly journals An atlas of cell types in the mammalian epididymis and vas deferens

2020 ◽  
Author(s):  
Vera D. Rinaldi ◽  
Elisa Donnard ◽  
Kyle J. Gellatly ◽  
Morten Rasmussen ◽  
Alper Kucukural ◽  
...  
Keyword(s):  
Vas Deferens ◽  
Immune Cell ◽  
Cell Types ◽  
Receptor Expression ◽  
Basal Cells ◽  
Regional Specialization ◽  
Clear Cells ◽  
Principal Cells ◽  
Mammalian Sperm ◽  
Genomic Clusters

ABSTRACTFollowing spermatogenesis in the testis, mammalian sperm continue to mature over the course of approximately 10 days as they transit a long epithelial tube known as the epididymis. The epididymis is comprised of multiple segments/compartments that, in addition to concentrating sperm and preventing their premature activation, play key roles in remodeling the protein, lipid, and RNA composition of maturing sperm. In order to understand the complex roles for the epididymis in reproductive biology, we generated a single cell atlas of gene expression from the murine epididymis and vas deferens. We recovered all the key cell types of the epididymal epithelium, including principal cells, clear cells, and basal cells, along with associated support cells that include fibroblasts, smooth muscle, macrophages and other immune cells. Moreover, our data illuminate extensive regional specialization of principal cell populations across the length of the epididymis, with a substantial fraction of segment-specific genes localized in genomic clusters of functionally-related genes. In addition to the extensive region-specific specialization of principal cells, we find evidence for functionally-specialized subpopulations of stromal cells, and, most notably, two distinct populations of clear cells. Analysis of ligand/receptor expression reveals a network of potential cellular signaling connections, with several predicted interactions between cell types that may play roles in immune cell recruitment and other aspects of epididymal function. Our dataset extends on existing knowledge of epididymal biology, and provides a wealth of information on potential regulatory and signaling factors that bear future investigation.

Cell-type specific calcium signalling in a Drosophila epithelium

1997 ◽  
Vol 110 (15) ◽  
pp. 1683-1692 ◽  
Author(s):  
P. Rosay ◽  
S.A. Davies ◽  
Y. Yu ◽  
A. Sozen ◽  
K. Kaiser ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Critical Role ◽  
Cell Signalling ◽  
Calcium Signalling ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Cell Types ◽  
Cytosolic Calcium ◽  
Atpase Inhibitor ◽  
Principal Cells

Calcium is a ubiquitous second messenger that plays a critical role in both excitable and non-excitable cells. Calcium mobilisation in identified cell types within an intact renal epithelium, the Drosophila melanogaster Malpighian tubule, was studied by GAL4-directed expression of an aequorin transgene. CAP2b, a cardioactive neuropeptide that stimulates fluid secretion by a mechanism involving nitric oxide, causes a rapid, dose-dependent rise in cytosolic calcium in only a single, genetically-defined, set of 77 principal cells in the main (secretory) segment of the tubule. In the absence of external calcium, the CAP2b-induced calcium response is abolished. In Ca2+-free medium, the endoplasmic reticulum Ca2+-ATPase inhibitor, thapsigargin, elevates [Ca2+]i only in the smaller stellate cells, suggesting that principal cells do not contain a thapsigargin-sensitive intracellular pool. Assays for epithelial function confirm that calcium entry is essential for CAP2b to induce a physiological response in the whole organ. Furthermore, the data suggest a role for calcium signalling in the modulation of the nitric oxide signalling pathway in this epithelium. The GAL4-targeting system allows general application to studies of cell-signalling and pharmacology that does not rely on invasive or cytotoxic techniques.

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