Multi-Electrode Array Analysis Identifies Complex Dopamine Responses and Glucose Sensing Properties of Substantia Nigra Neurons in Mouse Brain Slices

Dopaminergic (DA) midbrain neurons within the substantia nigra (SN) display an autonomous pacemaker activity that is crucial for dopamine release and voluntary movement control. Their progressive degeneration is a hallmark of Parkinson's disease. Their metabolically demanding activity-mode affects Ca2+ homeostasis, elevates metabolic stress, and renders SN DA neurons particularly vulnerable to degenerative stressors. Accordingly, their activity is regulated by complex mechanisms, notably by dopamine itself, via inhibitory D2-autoreceptors and the neuroprotective neuronal Ca2+ sensor NCS-1. Analyzing regulation of SN DA neuron activity-pattern is complicated by their high vulnerability. We studied this activity and its control by dopamine, NCS-1, and glucose with extracellular multi-electrode array (MEA) recordings from midbrain slices of juvenile and adult mice. Our tailored MEA- and spike sorting-protocols allowed high throughput and long recording times. According to individual dopamine-responses, we identified two distinct SN cell-types, in similar frequency: dopamine-inhibited and dopamine-excited neurons. Dopamine-excited neurons were either silent in the absence of dopamine, or they displayed pacemaker-activities, similar to that of dopamine-inhibited neurons. Inhibition of pacemaker-activity by dopamine is typical for SN DA neurons, and it can undergo prominent desensitization. We show for adult mice, that the number of SN DA neurons with desensitized dopamine-inhibition was increased (~60–100%) by a knockout of NCS-1, or by prevention of NCS-1 binding to D2-autoreceptors, while time-course and degrees of desensitization were not altered. The number of neurons with desensitized D2-responses was also higher (~65%) at high glucose-levels (25 mM), compared to lower glucose (2.5 mM), while again desensitization-kinetics were unaltered. However, spontaneous firing-rates were significantly higher at high glucose-levels (~20%). Moreover, transient glucose-deprivation (1 mM) induced a fast and fully-reversible pacemaker frequency reduction. To directly address and quantify glucose-sensing properties of SN DA neurons, we continuously monitored their electrical activity, while altering extracellular glucose concentrations stepwise from 0.5 mM up to 25 mM. SN DA neurons were excited by glucose, with EC50 values ranging from 0.35 to 2.3 mM. In conclusion, we identified a novel, common subtype of dopamine-excited SN neurons, and a complex, joint regulation of dopamine-inhibited neurons by dopamine and glucose, within the range of physiological brain glucose-levels.

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Faculty Opinions recommendation of Firing properties and functional connectivity of substantia nigra pars compacta neurones recorded with a multi-electrode array in vitro.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.4324964.4144063 ◽

2010 ◽

Author(s):

Antonio Pisani ◽

Giuseppe Sciamanna ◽

Enza Maria Valente

Keyword(s):

Functional Connectivity ◽

Substantia Nigra ◽

Electrode Array ◽

Substantia Nigra Pars Compacta ◽

Firing Properties ◽

Multi Electrode Array

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Multi-electrode array recording of gut pacemaker activity

10.36866/pn.67.32 ◽

2007 ◽

pp. 32-33

Author(s):

Shinsuke Nakayama

Keyword(s):

Electrode Array ◽

Pacemaker Activity ◽

Multi Electrode Array

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257-OR: High Glucose Levels and Risk of Vascular Diseases—Observational Studies and Mendelian Randomization Studies of the General Population

Diabetes ◽

10.2337/db19-257-or ◽

2019 ◽

Vol 68 (Supplement 1) ◽

pp. 257-OR

Author(s):

FRIDA EMANUELSSON ◽

SARAH MAROTT ◽

ANNE TYBJAERG-HANSEN ◽

BØRGE GRØNNE NORDESTGAARD ◽

MARIANNE BENN

Keyword(s):

General Population ◽

High Glucose ◽

Observational Studies ◽

Mendelian Randomization ◽

Vascular Diseases ◽

Glucose Levels

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Capacitance imaging for the discrimination of lipid region in atherosclerotic plaque ex vivo using polypyrrole-coated multi-walled carbon nanotube multi-electrode array

Current Applied Physics ◽

10.1016/j.cap.2019.08.006 ◽

2019 ◽

Vol 19 (11) ◽

pp. 1238-1244

Author(s):

Hyung Joon Kim

Keyword(s):

Carbon Nanotube ◽

Atherosclerotic Plaque ◽

Ex Vivo ◽

Electrode Array ◽

Multi Walled Carbon Nanotube ◽

Multi Electrode Array

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The frequency of Tim-3 on circulating Tfh cells was increased in type 2 diabetes mellitus patients

European Journal of Inflammation ◽

10.1177/2058739220982803 ◽

2020 ◽

Vol 18 ◽

pp. 205873922098280

Author(s):

Shuai Guo ◽

Xujie Yu ◽

Limei Wang ◽

Jing Jing ◽

Yuanyuan Sun ◽

...

Keyword(s):

Diabetes Mellitus ◽

Type 2 Diabetes ◽

Type 2 Diabetes Mellitus ◽

High Glucose ◽

C Peptide ◽

Glucose Levels ◽

Tfh Cells ◽

Fasting Plasma ◽

Healthy Donors

Type 2 diabetes mellitus (T2DM) is a chronic, low-grade inflammation disease. T follicular helper (Tfh) cells and T cell immunoglobulin and mucin domain 3 (Tim-3) are implicated in many immune diseases. This study aims to explore whether Tim-3 expression on Tfh cells is associated with T2DM progression. White blood cells (WBCs) were harvested from 30 patients with T2DM and 20 healthy donors. The abundance of circulating Tfh cells (cTfh) and the frequency of Tim-3 were analyzed by flow cytometry. Levels of fasting plasma glucose (FPG), insulin, hemoglobin A1C (HbA1C), and fasting plasma C-peptide were measured. Body mass index (BMI) and diabetes duration were also recorded. Patients with T2DM had higher numbers of cTfh cells. In addition, cTfh cells showed a negative correlation with HbA1C and diabetes duration, a positive correlation with fasting plasma C-peptide. The frequency of Tim-3 on cTfh cells was higher among T2DM patients compared with healthy donors. The in vitro experiment showed that high glucose levels increased the abundance cTfh cells but had no effect on Tim-3 expression. Our results suggest that cTfh cells and associated Tim-3 frequency may contribute to the progression of T2DM, and high glucose levels may influence cTfh cells directly.

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Patch-clamp and multi-electrode array electrophysiological analysis in acute mouse brain slices

STAR Protocols ◽

10.1016/j.xpro.2021.100442 ◽

2021 ◽

Vol 2 (2) ◽

pp. 100442

Author(s):

Kevin M. Manz ◽

Justin K. Siemann ◽

Douglas G. McMahon ◽

Brad A. Grueter

Keyword(s):

Patch Clamp ◽

Mouse Brain ◽

Brain Slices ◽

Electrode Array ◽

Electrophysiological Analysis ◽

Multi Electrode Array

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Modulation of intestinal cholesterol absorption by high glucose levels: impact on cholesterol transporters, regulatory enzymes, and transcription factors

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.90376.2008 ◽

2008 ◽

Vol 295 (5) ◽

pp. G873-G885 ◽

Cited By ~ 45

Author(s):

Z. Ravid ◽

M. Bendayan ◽

E. Delvin ◽

A. T. Sane ◽

M. Elchebly ◽

...

Keyword(s):

Transcription Factors ◽

Protein Expression ◽

High Glucose ◽

Cholesterol Absorption ◽

Cholesterol Homeostasis ◽

Cholesterol Transport ◽

Intestinal Cholesterol Absorption ◽

Cholesterol Uptake ◽

Glucose Levels

Growing evidence suggests that the small intestine may contribute to excessive postprandial lipemia, which is highly prevalent in insulin-resistant/Type 2 diabetic individuals and substantially increases the risk of cardiovascular disease. The aim of the present study was to determine the role of high glucose levels on intestinal cholesterol absorption, cholesterol transporter expression, enzymes controlling cholesterol homeostasis, and the status of transcription factors. To this end, we employed highly differentiated and polarized cells (20 days of culture), plated on permeable polycarbonate filters. In the presence of [14C]cholesterol, glucose at 25 mM stimulated cholesterol uptake compared with Caco-2/15 cells supplemented with 5 mM glucose ( P < 0.04). Because combination of 5 mM glucose with 20 mM of the structurally related mannitol or sorbitol did not change cholesterol uptake, we conclude that extracellular glucose concentration is uniquely involved in the regulation of intestinal cholesterol transport. The high concentration of glucose enhanced the protein expression of the critical cholesterol transporter NPC1L1 and that of CD36 ( P < 0.02) and concomitantly decreased SR-BI protein mass ( P < 0.02). No significant changes were observed in the protein expression of ABCA1 and ABCG8, which act as efflux pumps favoring cholesterol export out of absorptive cells. At the same time, 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity was decreased ( P < 0.007), whereas ACAT activity remained unchanged. Finally, increases were noted in the transcription factors LXR-α, LXR-β, PPAR-β, and PPAR-γ along with a drop in the protein expression of SREBP-2. Collectively, our data indicate that glucose at high concentrations may regulate intestinal cholesterol transport and metabolism in Caco-2/15 cells, thus suggesting a potential influence on the cholesterol absorption process in Type 2 diabetes.

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High glucose and insulin in combination cause insulin receptor substrate-1 and -2 depletion and protein kinase B desensitisation in primary cultured rat adipocytes: possible implications for insulin resistance in type 2 diabetes

Acta Endocrinologica ◽

10.1530/eje.0.1480157 ◽

2003 ◽

Vol 148 (1) ◽

pp. 157-167 ◽

Cited By ~ 43

Author(s):

J Buren ◽

HX Liu ◽

J Lauritz ◽

JW Eriksson

Keyword(s):

Glucose Uptake ◽

High Glucose ◽

Insulin Treatment ◽

Insulin Signalling ◽

Binding Capacity ◽

Insulin Binding ◽

Rat Adipocytes ◽

Glucose Levels ◽

High Insulin ◽

The Right

OBJECTIVE: The purpose of this study was to investigate the cellular effects of long-term exposure to high insulin and glucose levels on glucose transport and insulin signalling proteins. DESIGN AND METHODS: Rat adipocytes were cultured for 24 h in different glucose concentrations with 10(4) microU/ml of insulin or without insulin. After washing, (125)I-insulin binding, basal and acutely insulin-stimulated d-[(14)C]glucose uptake, and insulin signalling proteins and glucose transporter 4 (GLUT4) were assessed. RESULTS: High glucose (15 and 25 mmol/l) for 24 h induced a decrease in basal and insulin-stimulated glucose uptake compared with control cells incubated in low glucose (5 or 10 mmol/l). Twenty-four hours of insulin treatment decreased insulin binding capacity by approximately 40%, and shifted the dose-response curve for insulin's acute effect on glucose uptake 2- to 3-fold to the right. Twenty-four hours of insulin treatment reduced basal and insulin-stimulated glucose uptake only in the presence of high glucose (by approximately 30-50%). At high glucose, insulin receptor substrate-1 (IRS-1) expression was downregulated by approximately 20-50%, whereas IRS-2 was strongly upregulated by glucose levels of 10 mmol/l or more (by 100-400%). Insulin treatment amplified the suppression of IRS-1 when combined with high glucose and also IRS-2 expression was almost abolished. Twenty-four hours of treatment with high glucose or insulin, alone or in combination, shifted the dose-response curve for insulin's effect to acutely phosphorylate protein kinase B (PKB) to the right. Fifteen mmol/l glucose increased GLUT4 in cellular membranes (by approximately 140%) compared with 5 mmol/l but this was prevented by a high insulin concentration. CONCLUSIONS: Long-term exposure to high glucose per se decreases IRS-1 but increases IRS-2 content in rat adipocytes and it impairs glucose transport capacity. Treatment with high insulin downregulates insulin binding capacity and, when combined with high glucose, it produces a marked depletion of IRS-1 and -2 content together with an impaired sensitivity to insulin stimulation of PKB activity. These mechanisms may potentially contribute to insulin resistance in type 2 diabetes.

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