scholarly journals Cadmium versus Lanthanum Effects on Spontaneous Electrical Activity and Expression of Connexin Isoforms Cx26, Cx36, and Cx45 in the Human Fetal Cortex

2019 ◽  
Vol 30 (3) ◽  
pp. 1244-1259 ◽  
Author(s):  
Dusica M Kocovic ◽  
Pallavi V Limaye ◽  
Lauren C H Colburn ◽  
Mandakini B Singh ◽  
Milena M Milosevic ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Neuronal Development ◽  
Brain Slices ◽  
Immunohistochemical Analysis ◽  
Fetal Tissue ◽  
Cortical Layer ◽  
Cortical Plate ◽  
Cellular Mechanisms ◽  
Spontaneous Electrical Activity ◽  
New Information

Abstract Electrical activity is important for brain development. In brain slices, human subplate neurons exhibit spontaneous electrical activity that is highly sensitive to lanthanum. Based on the results of pharmacological experiments in human fetal tissue, we hypothesized that hemichannel-forming connexin (Cx) isoforms 26, 36, and 45 would be expressed on neurons in the subplate (SP) zone. RNA sequencing of dissected human cortical mantles at ages of 17–23 gestational weeks revealed that Cx45 has the highest expression, followed by Cx36 and Cx26. The levels of Cx and pannexin expression between male and female fetal cortices were not significantly different. Immunohistochemical analysis detected Cx45- and Cx26-expressing neurons in the upper segment of the SP zone. Cx45 was present on the cell bodies of human SP neurons, while Cx26 was found on both cell bodies and dendrites. Cx45, Cx36, and Cx26 were strongly expressed in the cortical plate, where newborn migrating neurons line up to form cortical layers. New information about the expression of 3 “neuronal” Cx isoforms in each cortical layer/zone (e.g., SP, cortical plate) and pharmacological data with cadmium and lanthanum may improve our understanding of the cellular mechanisms underlying neuronal development in human fetuses and potential vulnerabilities.

Measurement of spontaneous neuronal membrane activity by time lapse confocal microscopy

1995 ◽  
Vol 53 ◽  
pp. 972-973
Author(s):  
R H. Selinfreund ◽  
A. H. Cornell-Bell
Keyword(s):  
Membrane Potential ◽  
Confocal Microscopy ◽  
Patch Clamp ◽  
Electrical Activity ◽  
Time Lapse ◽  
Neuronal Firing ◽  
Neuronal Membrane ◽  
Pituitary Cells ◽  
Patch Clamp Recording ◽  
Spontaneous Electrical Activity

Cellular electrophysiological properties are normally monitored by standard patch clamp techniques . The combination of membrane potential dyes with time-lapse laser confocal microscopy provides a more direct, least destructive rapid method for monitoring changes in neuronal electrical activity. Using membrane potential dyes we found that spontaneous action potential firing can be detected using time-lapse confocal microscopy. Initially, patch clamp recording techniques were used to verify spontaneous electrical activity in GH4\C1 pituitary cells. It was found that serum depleted cells had reduced spontaneous electrical activity. Brief exposure to the serum derived growth factor, IGF-1, reconstituted electrical activity. We have examined the possibility of developing a rapid fluorescent assay to measure neuronal activity using membrane potential dyes. This neuronal regeneration assay has been adapted to run on a confocal microscope. Quantitative fluorescence is then used to measure a compounds ability to regenerate neuronal firing.The membrane potential dye di-8-ANEPPS was selected for these experiments. Di-8- ANEPPS is internalized slowly, has a high signal to noise ratio (40:1), has a linear fluorescent response to change in voltage.

Electrical activity of the ventromedial nucleus of the hypothalamus

1959 ◽  
Vol 197 (4) ◽  
pp. 829-834 ◽  
Author(s):  
Dana C. Brooks
Keyword(s):  
Electrical Activity ◽  
Slow Waves ◽  
Ventromedial Nucleus ◽  
Spontaneous Electrical Activity ◽  
Pentobarbital Anesthesia

The spontaneous electrical activity of the ventromedial nucleus was studied in the cat under pentobarbital anesthesia and in the unanesthetized, unrestrained state. Under light pentobarbital anesthesia the activity of the nucleus is characterized by a predominant 9–15 cps, 50–100 µv component which is uniform from second to second. With small additional doses of anesthesia there is a selective depression of this activity; with recovery from light anesthesia this activity is gradually replaced by irregular, large, slow waves characteristic of sleep. When the unanesthetized animal is aroused 20–35 cps activity having an amplitude of 40 µv or more appears in the nucleus. While the pattern of activity during sleep resembles that seen elsewhere in the hypothalamus, the activity seen during barbiturate anesthesia and during arousal is confined to the nucleus and not seen in other parts of the diencephalon.

Optical approaches to ontogeny of electrical activity and related functional organization during early heart development

1991 ◽  
Vol 71 (1) ◽  
pp. 53-91 ◽  
Author(s):  
K. Kamino
Keyword(s):  
Electrical Activity ◽  
Heart Development ◽  
Functional Organization ◽  
Embryonic Heart ◽  
Optical Recording ◽  
Additional Advantage ◽  
Physiological Functions ◽  
Spontaneous Electrical Activity ◽  
Somite Stage ◽  
Voltage Sensitive Dyes

Direct intracellular measurement of electrical events in the early embryonic heart is impossible because the cells are too small and frail to be impaled with microelectrodes; it is also not possible to apply conventional electrophysiological techniques to the early embryonic heart. For these reasons, complete understanding of the ontogeny of electrical activity and related physiological functions of the heart during early development has been hampered. Optical signals from voltage-sensitive dyes have provided a new powerful tool for monitoring changes in transmembrane voltage in a wide variety of living preparations. With this technique it is possible to make optical recordings from the cells that are inaccessible to microelectrodes. An additional advantage of the optical method for recording membrane potential activity is that electrical activity can be monitored simultaneously from many sites in a preparation. Thus, applying a multiple-site optical recording method with a 100- or 144-element photodiode array and voltage-sensitive dyes, we have been able to monitor, for the first time, spontaneous electrical activity in prefused cardiac primordia in the early chick embryos at the six- and the early seven-somite stages of development. We were able to determine that the time of initiation of the contraction is the middle period of the nine-somite stage. In the rat embryonic heart, the onset of spontaneous electrical activity and contraction occurs at the three-somite stage. In this review, a new view of the ontogenetic sequence of spontaneous electrical activity and related physiological functions such as ionic properties, pacemaker function, conduction, and characteristics of excitation-contraction coupling in the early embryonic heart are discussed.

Long-term observations of spontaneous electrical activity of the uterine smooth muscle

1959 ◽  
Vol 196 (2) ◽  
pp. 343-350 ◽  
Author(s):  
C. Y. Kao
Keyword(s):  
Smooth Muscle ◽  
Electrical Activity ◽  
Action Potentials ◽  
Local Conditions ◽  
Pregnant Uterus ◽  
Implanted Electrodes ◽  
Spontaneous Electrical Activity ◽  
Myometrial Cells ◽  
Uterine Smooth Muscle

The spontaneous electrical activity of uterine smooth muscle was rather variable when acute observations were made. Therefore, a series of chronic experiments was performed with implanted electrodes to monitor a group of myometrial cells under different physiological conditions for periods up to eight weeks. The results showed that consistent behavior of myometrial cells could be observed provided similar hormonal status was maintained. Action potentials were rare or absent in myometrium of oophorectomized animals but were caused to appear by estrogen. In the pregnant uterus, action potentials increased both in amplitude and frequency of discharge as parturition approached, reached a peak at that time, and then declined in the postpartum days. The results indicated that in estrogen treatment and in parturition activities of myometrial cells were more synchronous. There was suggestive evidence that there were central impulses initiating activity in the pregnant uterus, and that the responses of the myometrium were affected by the local conditions.

Nucleotide action on spontaneous electrical activity of calcium deficient nerve

1967 ◽  
Vol 70 (3) ◽  
pp. 257-264 ◽  
Author(s):  
Albert S. Kuperman ◽  
Michiko Okamoto ◽  
Elaine Gallin
Keyword(s):  
Electrical Activity ◽  
Spontaneous Electrical Activity

scholarly journals Cell type-specific effects of isoflurane on two distinct afferent inputs to cortical layer 1

2020 ◽  
Author(s):  
Caitlin A. Murphy ◽  
Matthew I. Banks
Keyword(s):  
Ex Vivo ◽  
Brain Slices ◽  
Pyramidal Cells ◽  
Cellular Level ◽  
Cortical Layer ◽  
Cell Type ◽  
Specific Effects ◽  
Primary Mouse ◽  
Cell Type Specific ◽  
Synaptic Responses

ABSTRACTBackgroundWhile their behavioral effects are well-characterized, the mechanisms by which anaesthetics induce loss of consciousness are largely unknown. Anaesthetics may disrupt integration and propagation of information in corticothalamic networks. Recent studies have shown that isoflurane diminishes synaptic responses of thalamocortical (TC) and corticocortical (CC) afferents in a pathway-specific manner. However, whether the synaptic effects of isoflurane observed in extracellular recordings persist at the cellular level has yet to be explored.MethodsHere, we activate TC and CC layer 1 inputs in non-primary mouse neocortex in ex vivo brain slices and explore the degree to which isoflurane modulates synaptic responses in pyramidal cells and in two inhibitory cell populations, somatostatin-positive (SOM+) and parvalbumin-positive (PV+) interneurons.ResultsWe show that the effects of isoflurane on synaptic responses and intrinsic properties of these cells varies among cell type and by cortical layer. Layer 1 inputs to L4 pyramidal cells were suppressed by isoflurane at both TC and CC synapses, while those to L2/3 pyramidal cells and PV+ interneurons were not. TC inputs to SOM+ cells were rarely observed at all, while CC inputs to SOM+ interneurons were robustly suppressed by isoflurane.ConclusionsThese results suggest a mechanism by which isoflurane disrupts integration and propagation of thalamocortical and intracortical signals.

scholarly journals Dab2IP Regulates Neuronal Positioning, Rap1 Activity and Integrin Signaling in the Developing Cortex

2015 ◽  
Vol 37 (2) ◽  
pp. 131-141 ◽  
Author(s):  
Shuhong Qiao ◽  
Ramin Homayouni
Keyword(s):  
Brain Development ◽  
Cortical Neurons ◽  
Ventricular Zone ◽  
Physiological Role ◽  
Immunohistochemical Analysis ◽  
Superficial Layer ◽  
Tumor Formation ◽  
Intermediate Zone ◽  
Cortical Plate ◽  
Integrin Signaling

Dab2IP (DOC-2/DAB2 interacting protein) is a GTPase-activating protein which is involved in various aspects of brain development in addition to its roles in tumor formation and apoptosis in other systems. In this study, we carefully examined the expression profile of Dab2IP and investigated its physiological role during brain development using a Dab2IP-knockdown (KD) mouse model created by retroviral insertion of a LacZ-encoding gene-trapping cassette. LacZ staining revealed that Dab2IP is expressed in the ventricular zone as well as the cortical plate and the intermediate zone. Immunohistochemical analysis showed that Dab2IP protein is localized in the leading process and proximal cytoplasmic regions of migrating neurons in the intermediate zone. Bromodeoxyuridine birth dating experiments in combination with immunohistochemical analysis using layer-specific markers showed that Dab2IP is important for proper positioning of a subset of layer II-IV neurons in the developing cortex. Notably, neuronal migration was not completely disrupted in the cerebral cortex of Dab2IP-KD mice and disruption of migration was not strictly layer specific. Previously, we found that Dab2IP regulates multipolar transition in cortical neurons. Others have shown that Rap1 regulates the transition from multipolar to bipolar morphology in migrating postmitotic neurons through N-cadherin signaling and somal translocation in the superficial layer of the cortical plate through integrin signaling. Therefore, we examined whether Rap1 and integrin signaling were affected in Dab2IP-KD brains. We found that Dab2IP-KD resulted in higher levels of activated Rap1 and integrin in the developing cortex. Taken together, our results suggest that Dab2IP plays an important role in the migration and positioning of a subpopulation of later-born (layers II-IV) neurons, likely through the regulation of Rap1 and integrin signaling.

Chronic electrical activity of cat intestine

1984 ◽  
Vol 246 (4) ◽  
pp. G335-G341 ◽  
Author(s):  
A. Bortoff ◽  
L. F. Sillin ◽  
A. Sterns
Keyword(s):  
Electrical Activity ◽  
Slow Waves ◽  
Intestinal Anastomoses ◽  
Bipolar Electrodes ◽  
Spontaneous Electrical Activity ◽  
Central Origin ◽  
Variable Duration

Spontaneous electrical activity was recorded with bipolar electrodes from the gastrointestinal tracts of unanesthetized fasted cats (upper and lower cut-off frequencies: 35 and 3 Hz). In addition to slow waves (SWs) and spike potentials (SPs), the following three patterns of activity were recorded that are not observed in vitro. 1) Intense bursts of SPs (migrating spike complexes, MSCs) migrate caudally at a velocity of approximately 1 mm/s. MSCs resemble migrating myoelectric complexes (MMCs) in their velocity and by their traversal of intestinal anastomoses. SWs are usually suppressed during and immediately after the MSC, and, on their return, propagate at a higher velocity than they do prior to the MSC. Unlike its effect on MMCs, motilin does not appear to elicit MSCs, a finding consistent with the fact that MSCs occur infrequently in the duodenum and not at all in the antrum. 2) Bursts of SPs are found in the absence of recorded SWs. The SP bursts are of variable duration and occur virtually simultaneously at several recording sites, or propagate at 1-2 cm/s in either direction along the jejunum. The more usual caudally propagating SPs occur when SWs reappear. 3) "Minute rhythms," periods of spiking SWs, occur simultaneously over long lengths of upper bowel, sometimes including antrum, at intervals of about 1-2 min. It is proposed that, despite their differences, the cat MSC may be the functional counterpart of the MMC, that cat SWs are not omnipresent, and that the minute rhythms described here are of central origin.

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