Astrocytes in the dorsal vagal complex are not activated by systemic glucoprivation and their chemogenetic activation does not elicit homeostatic glucoregulatory responses in mice

The dorsal vagal complex (DVC) is a brainstem site regulating diverse aspects of physiology including food intake and blood glucose homeostasis. Astrocytes are purported to play an active role in regulating DVC function and, by extension, physiological parameters. Previous work has demonstrated that DVC astrocytes directly sense hormones that regulate food intake and blood glucose and are critical for their effect. In addition, DVC astrocytes in ex vivo slices respond to low tissue glucose. The response of neurons, including catecholaminergic neurons, to low glucose is conditional on intact astrocyte signalling in slice preparations suggesting astrocytes are possibly the primary sensors of glucose deprivation (glucoprivation). Based on these findings we hypothesised that if DVC astrocytes act as glucoprivation sensors in vivo they would both show a response to systemic glucoprivation and drive physiological responses to restore blood glucose. We found that 2 hours of systemic glucoprivation induced neither FOS nor glial fibrillary acidic protein (GFAP)-immunoreactivity in DVC astrocytes, specifically those in the nucleus of the solitary tract (NTS). Furthermore, we found that while chemogenetic activation of DVC astrocytes suppressed food intake by reducing both meal size and meal number, this manipulation also suppressed food intake under conditions of glucoprivation. Chemogenetic activation of DVC astrocytes did not increase basal blood glucose nor protect against insulin-induced hypoglycaemia. In male mice chemogenetic DVC astrocyte activation did not alter glucose tolerance, in female mice the initial glucose excursion was reduced, suggesting enhanced glucose absorption. Taken together this suggests that as a whole-population DVC astrocytes do not function as glucoprivation sensors in vivo in mice. Instead, we propose that DVC astrocytes play an indispensable, homeostatic role to maintain the function of glucoregulatory neuronal circuitry.

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Dihydrotestosterone attenuates hypoxia inducible factor-1α and cyclooxygenase-2 in cerebral arteries during hypoxia or hypoxia with glucose deprivation

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00446.2011 ◽

2011 ◽

Vol 301 (5) ◽

pp. H1882-H1890 ◽

Cited By ~ 11

Author(s):

Kristen L. Zuloaga ◽

Rayna J. Gonzales

Keyword(s):

Smooth Muscle ◽

Androgen Receptor ◽

Vascular Smooth Muscle ◽

Ex Vivo ◽

Cerebral Arteries ◽

Hypoxia Inducible Factor ◽

Glucose Deprivation ◽

Male Rats ◽

Cox 2

Dihydrotestosterone (DHT) attenuates cytokine-induced cyclooxygenase-2 (COX-2) in coronary vascular smooth muscle. Since hypoxia inducible factor-1α (HIF-1α) activation can lead to COX-2 production, this study determined the influence of DHT on HIF-1α and COX-2 following hypoxia or hypoxia with glucose deprivation (HGD) in the cerebral vasculature. COX-2 and HIF-1α levels were assessed via Western blot, and HIF-1α activation was indirectly measured via a DNA binding assay. Experiments were performed using cerebral arteries isolated from castrated male rats treated in vivo with placebo or DHT (18 days) followed by hypoxic exposure ex vivo (1% O2), cerebral arteries isolated from castrated male rats treated ex vivo with vehicle or DHT (10 or 100 nM; 18 h) and then exposed to hypoxia ex vivo (1% O2), or primary human brain vascular smooth muscle cells treated with DHT (10 nM; 6 h) or vehicle then exposed to hypoxia or HGD. Under normoxic conditions, DHT increased COX-2 (cells 51%; arteries ex vivo 31%; arteries in vivo 161%) but had no effect on HIF-1α. Following hypoxia or HGD, HIF-1α and COX-2 levels were increased; this response was blunted by DHT (cells HGD: −47% COX-2, −34% HIF-1α; cells hypoxia: −29% COX-2, −54% HIF-1α; arteries ex vivo: −37% COX-2; arteries in vivo: −35% COX-2) and not reversed by androgen receptor blockade. Hypoxia-induced HIF-1α DNA-binding was also attenuated by DHT (arteries ex vivo and in vivo: −55%). These results demonstrate that upregulation of COX-2 and HIF-1α in response to hypoxia is suppressed by DHT via an androgen receptor-independent mechanism.

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Regulation of food intake by astrocytes in the brainstem dorsal vagal complex

10.1101/543991 ◽

2019 ◽

Author(s):

Alastair J. MacDonald ◽

Fiona E. Holmes ◽

Craig Beall ◽

Anthony E. Pickering ◽

Kate L.J. Ellacott

Keyword(s):

Food Intake ◽

Area Postrema ◽

Active Role ◽

Brain Regions ◽

Negative Energy ◽

Motor Nucleus ◽

Dorsal Vagal Complex ◽

Structural Support ◽

Dorsal Motor Nucleus ◽

Hypothalamic Arcuate Nucleus

Food intake is controlled by the coordinated action of numerous brain regions but a complete understanding remains elusive. Of these brain regions the brainstem dorsal vagal complex (DVC) is the first site for integration of visceral synaptic and hormonal cues that act to inhibit food intake. The DVC consists of three nuclei: the nucleus of the solitary tract (NTS), area postrema (AP) and dorsal motor nucleus of the vagus (DMX). Targeted chemogenetic activation of appetite-responsive NTS neuronal populations causes short term decreases in food intake. Astrocytes are a class of glial cell which provide metabolic and structural support to neurons and play an active role in modulating neurotransmission. Within the hypothalamic arcuate nucleus (ARC) astrocytes are regulated by both positive and negative energy balance and express receptors for hormones that influence satiety and hunger. Chemogenetic activation of these ARC astrocytes alters food intake. Since NTS astrocytes respond to vagal stimulation, we hypothesised that they may be involved in mediating satiety. Here we show that NTS astrocytes show plastic alterations in morphology following excess food consumption and that chemogenetic activation of DVC astrocytes causes a decrease in food intake, by recruiting an appetite-inhibiting circuit, without producing aversion. These findings are the first using genetically-targeted manipulation of DVC astrocytes to demonstrate their role in the brain’s regulation of food intake.

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Abstract 2487: Ischemia/Reperfusion Injury Impairs Myogenic Tone of Cerebral Vessels in both Ischemic and Nonischemic Hemispheres: Differential Role of Oxidative Stress.

Stroke ◽

10.1161/str.43.suppl_1.a2487 ◽

2012 ◽

Vol 43 (suppl_1) ◽

Author(s):

Maha Coucha ◽

Weiguo Li ◽

Adviye Ergul

Keyword(s):

Oxidative Stress ◽

Wistar Rats ◽

Ischemia Reperfusion Injury ◽

Ex Vivo ◽

Ischemia Reperfusion ◽

Cerebral Arteries ◽

Glucose Deprivation ◽

Myogenic Tone ◽

Ex Vivo Model

Cerebrovascular autoregulation and reactivity are critical to maintain constant perfusion during ischemic brain injury. It is known that ischemia/ reperfusion (I/R) injury and resulting oxidative stress impair vessel reactivity in ischemic hemisphere. Yet the behavior of vessels in nonischemic hemisphere is still unexplored. Hypothesis: I/R injury impairs myogenic tone of vessels in both ischemic and nonischemic hemispheres via increased peroxynitrite (ONOO - ) generation. Methods: Middle cerebral arteries (MCA) isolated from age matched male Wistar rats (n=6) subjected to 30 min MCA occlusion (MCAO)/45 min reperfusion, or MCAO followed by treatment with ONOO - scavenger FeTPPs (20mg/kg) at reperfusion were pressurized in arteriograph chamber. In another set of animals, MCA isolated from control Wistar rats were exposed to ex vivo oxygen-glucose deprivation (OGD) then their myogenic tones across the pressure range were determined. Results: I/R injury impaired myogenic tone of vessels in both ischemic and nonischemic sides albeit to a different degree. Interestingly FeTPPs restored myogenic tone of vessels from ischemic side only ( Table ). Vessels exposed to ex vivo and in vivo hypoxia experienced loss of myogenic tone. The reduction of myogenic tone % by OGD is similar to I/R injury. Conclusion: Our ex vivo model of hypoxia is a valuable method to assess the ischemic insult on vessel reactivity. Increased ONOO - production is one of the underlying mechanisms of loss of tone under I/R injury in ischemic hemisphere, but the impairment of myogenic tone in nonischemic hemisphere involves other mechanisms. Understanding how I/R alters myogenic tone and ultimately cerebral perfusion in both ischemic and nonischemic hemispheres is vital in improving current preventive and therapeutic strategies for acute stroke. + p<0.001, * p< 0.05 vs Sham, # p<0.001 vs ischemic MCA , ** p<0.01 vs nonischemic MCA

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In-Vivo and Ex-Vivo Measurements of Blood Glucose Using Whispering Gallery Modes

Sensors ◽

10.3390/s20030830 ◽

2020 ◽

Vol 20 (3) ◽

pp. 830 ◽

Cited By ~ 3

Author(s):

Louis W. Y. Liu ◽

Abhishek Kandwal ◽

A. Kogut ◽

Z. E. Eremenko ◽

E. Kogut ◽

...

Keyword(s):

Blood Glucose ◽

Millimeter Wave ◽

Linear Correlation ◽

Ex Vivo ◽

Water Solution ◽

Resonance Method ◽

Vacuum Suction ◽

Whispering Gallery ◽

Glucose Water

The permittivity of blood glucose is not a strong function of its concentration in microwave or millimeter-wave frequencies. Measuring glucose concentrations remains a challenge, particularly in the presence of interference caused by the ambient leaky waves. In this paper, however, we demonstrate that a near-linear correlation between the glucose concentration and the blood permittivity was noticeably observed at a whispering gallery mode resonance. Method: the proposed sensor was a vacuum suction aspirator partially wounded with a turn of the Goubau line. This arrangement enabled a fixed cylindrical volume of a skin tissue bump or glucose/water solution to be formed and used as a whispering gallery resonator for in-vivo and ex-vivo measurements. Results: in the in-vivo study, a near-linear correlation between the glucose levels and the S21 parameters was noticeably observed at the fundamental whispering gallery resonance (i.e., at 2.18 GHz). In the ex-vivo study, a similar correlation was observed between the concentration of a glucose/water solution and the S21 parameters 56.6 GHz. Conclusion: the results of both investigations were consistent not only with the invasive measurements using the Accu-checkTM, but also with the conclusion drawn by some other research groups who have successfully measured blood glucose concentrations at millimeter-wave frequencies.

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Role of Neuronal Energy Status in the Regulation of Adenosine 5′-Monophosphate-Activated Protein Kinase, Orexigenic Neuropeptides Expression, and Feeding Behavior

Endocrinology ◽

10.1210/en.2004-0968 ◽

2005 ◽

Vol 146 (1) ◽

pp. 3-10 ◽

Cited By ~ 102

Author(s):

Kichoon Lee ◽

Bing Li ◽

Xiaochun Xi ◽

Yeunsu Suh ◽

Roy J. Martin

Keyword(s):

Protein Kinase ◽

Food Intake ◽

Feeding Behavior ◽

High Glucose ◽

Ex Vivo ◽

Nutrient Sensing ◽

Central Administration ◽

Energy Status ◽

Low Glucose

Nutrient sensing in the hypothalamus is tightly related to food intake regulation. However, the mechanisms by which the nutrient-sensing cells of the brain translate this signal of energy need into feeding behavior via regulation of neuropeptide expression are not known. To address this issue, we investigated two neuronal cell lines expressing agouti-related protein (AgRP), ex vivo hypothalamic tissues, and in vivo whole animals. Maintaining cells in a low cellular ATP concentration generated by low glucose, 2-deoxyglucose (2-DG), ATP synthesis inhibitor, and 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside increased phosphorylation of AMP-activated protein kinase (AMPK) and increased AgRP expression, whereas maintaining cells in high ATP status by high glucose and pyruvate supplementation in 2-DG-treated cells decreased phosphorylation of AMPK and decreased AgRP expression. Overexpression of a dominant-inhibitory mutant of AMPK significantly decreased low-glucose- or 2-DG-induced AgRP expression. Furthermore, ex vivo hypothalamus culture in high glucose concentrations decreased both expression and phosphorylation of AMPK and expression of both AgRP and neuropeptide Y, whereas pyruvate supplementation suppressed a 2-DG-induced AgRP expression. Finally, our in vivo studies clearly show that central administration of pyruvate dramatically delayed 2-DG-induced food intake. These data indicate that modulation of ATP levels in neuronal cells triggers a cascade of events via AMPK that modulate feeding behavior to restore energy status of cells.

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Antihyperglycemic Effect of Lavandula pedunculata: In Vivo, In Vitro and Ex Vivo Approaches

Pharmaceutics ◽

10.3390/pharmaceutics13122019 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2019

Author(s):

Salima Boutahiri ◽

Mohamed Bouhrim ◽

Chayma Abidi ◽

Hamza Mechchate ◽

Ali S. Alqahtani ◽

...

Keyword(s):

Glucose Tolerance ◽

Aqueous Extract ◽

Digestive Enzymes ◽

Ex Vivo ◽

Glucose Absorption ◽

Oral Glucose ◽

Oral Glucose Tolerance ◽

Antihyperglycemic Effect

Lavandula pedunculata (Mill.) Cav. (LP) is one of lavender species traditionally used in Morocco to prevent or cure diabetes, alone or in the form of polyherbal preparations (PHP). Therefore, the primary objective of this study was to test the antihyperglycemic effect of the aqueous extract of LP, alone and in combination with Punica granatum L. (PG) and Trigonella foenum-graecum L. (FGK). The secondary objective was to explore some mechanisms of action on the digestive functions. The antihyperglycemic effect of the aqueous extract of LP, alone and in combination with PG and FGK, was studied in vivo using an oral glucose tolerance test (OGTT). In addition, LP extract was tested on the activities of some digestive enzymes (pancreatic α-amylase and intestinal α-glucosidase) in vitro and on the intestinal absorption of glucose ex vivo using a short-circuit current (Isc) technique. Acute and chronic oral administration of LP aqueous extract reduced the peak of the glucose concentration (30 min, p < 0.01) and the area under the curve (AUC, p < 0.01). The effect of LP + PG was at the same amplitude to that of the positive control Metformin (MET). LP aqueous extract inhibited the pancreatic α-amylase with an IC50 almost identical to acarbose (0.44 ± 0.05 mg/mL and 0.36 ± 0.02 mg/mL, respectively), as well as the intestinal α-glucosidase, (IC50 = 131 ± 20 µg/mL) and the intestinal glucose absorption (IC50 = 81.28 ± 4.01 µg/mL) in concentration-dependent manners. LP aqueous extract exhibited potent actions on hyperglycemia, with an inhibition on digestive enzymes and glucose absorption. In addition, the combination with PG and FGK enhanced oral glucose tolerance in rats. These findings back up the traditional use of LP in type 2 diabetes treatment and the effectiveness of the alternative and combinative poly-phytotherapy (ACPP).

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Inhibition of miR-143 during ischemia cerebral injury protects neurones through recovery of the hexokinase 2-mediated glucose uptake

Bioscience Reports ◽

10.1042/bsr20170216 ◽

2017 ◽

Vol 37 (4) ◽

Cited By ~ 9

Author(s):

Xianzhu Zeng ◽

Na Liu ◽

Jing Zhang ◽

Lei Wang ◽

Zhecheng Zhang ◽

...

Keyword(s):

Glucose Uptake ◽

Target Genes ◽

Ex Vivo ◽

Glucose Deprivation ◽

Artery Occlusion ◽

Cerebral Injury ◽

Mrna Levels ◽

Hexokinase 2 ◽

New Strategy

Ischemic stroke, a major cause of death, is caused by occlusion of a blood vessel, resulting in significant reduction in regional cerebral blood flow. MiRNAs are a family of short noncoding RNAs (18–22 nts) and bind the 3′-UTR of their target genes to suppress the gene expression post-transcriptionally. In the present study, we report that miR-143 is down-regulated in rat neurones but highly expressed in astrocytes. In vivo middle cerebral artery occlusion (MCAO) and ex vivo oxygen-glucose deprivation (OGD) results showed that miR-143 was significantly induced by ischemia injury. Meanwhile, we observed suppression of glucose uptake and lactate product of rat brain and primary neurones after MCAO or OGD. The glycolysis enzymes hexokinase 2 (HK2), PKM2, and LDHA were inhibited by MCAO or OGD at protein and mRNA levels. In addition, overexpression of miR-143 significantly inhibited HK2 expression, glucose uptake, and lactate product. We report that HK2 is a direct target of miR-143. Importantly, restoration of HK2 in miR-143 overexpressing rat neurones recovered glucose uptake and lactate product. Our results demonstrated inhibition of miR-143 during OGD could protect rat neuronal cells from ischemic brain injury (IBI). In summary, the present study reveals a miRNA-mediated neuron protection during IBI, providing a new strategy for the development of therapeutic agents against IBI.

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The Effects of Major Mushroom Bioactive Compounds on Mechanisms That Control Blood Glucose Level

Journal of Fungi ◽

10.3390/jof7010058 ◽

2021 ◽

Vol 7 (1) ◽

pp. 58

Author(s):

Jelena Aramabašić Jovanović ◽

Mirjana Mihailović ◽

Aleksandra Uskoković ◽

Nevena Grdović ◽

Svetlana Dinić ◽

...

Keyword(s):

Diabetes Mellitus ◽

Blood Glucose ◽

Bioactive Compounds ◽

Molecular Mechanisms ◽

Human Life ◽

Cell Mass ◽

Glucose Absorption ◽

Mushroom Species

Diabetes mellitus is a life-threatening multifactorial metabolic disorder characterized by high level of glucose in the blood. Diabetes and its chronic complications have a significant impact on human life, health systems, and countries’ economies. Currently, there are many commercial hypoglycemic drugs that are effective in controlling hyperglycemia but with several serious side-effects and without a sufficient capacity to significantly alter the course of diabetic complications. Over many centuries mushrooms and their bioactive compounds have been used in the treatment of diabetes mellitus, especially polysaccharides and terpenoids derived from various mushroom species. This review summarizes the effects of these main mushroom secondary metabolites on diabetes and underlying molecular mechanisms responsible for lowering blood glucose. In vivo and in vitro data revealed that treatment with mushroom polysaccharides displayed an anti-hyperglycemic effect by inhibiting glucose absorption efficacy, enhancing pancreatic β-cell mass, and increasing insulin-signaling pathways. Mushroom terpenoids act as inhibitors of α-glucosidase and as insulin sensitizers through activation of PPARγ in order to reduce hyperglycemia in animal models of diabetes. In conclusion, mushroom polysaccharides and terpenoids can effectively ameliorate hyperglycemia by various mechanisms and can be used as supportive candidates for prevention and control of diabetes in the future.

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Automated diffusion-based parcellation of the hypothalamus reveals subunit-specific associations with obesity

Scientific Reports ◽

10.1038/s41598-020-79289-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Melanie Spindler ◽

Jale Özyurt ◽

Christiane M. Thiel

Keyword(s):

Food Intake ◽

Ex Vivo ◽

Functional Anatomy ◽

Mean Diffusivity ◽

Structural Mri ◽

Clustering Methods ◽

Endocrine Activity ◽

Human Connectome Project ◽

Using Data

AbstractThe hypothalamus is a small, yet highly versatile structure mainly involved in bodily functions such as control of food intake and endocrine activity. Functional anatomy of different hypothalamic areas is mainly investigated using structural MRI, validated by ex-vivo histological studies. Based on diffusion-weighted imaging (DWI), recent automated clustering methods provide robust tools for parcellation. Using data of 100 healthy adults provided by the Human Connectome Project Database, we applied DWI-based automated clustering to the hypothalamus and related microstructural properties in these hypothalamic compartments to obesity. Our results suggest that the hypothalamus can be reliably partitioned into four clusters in each hemisphere using diffusion-based parcellation. These correspond to an anterior–superior, anterior-inferior, intermediate, and posterior cluster. Obesity was predicted by mean diffusivity of the anterior–superior cluster, suggesting altered inhibition of food intake. The proposed method provides an automated hypothalamic parcellation technique based on DWI data to explore anatomy and function of hypothalamic subunits in vivo in humans.

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Longevity-Extending MetAP2 Inhibitors Induce Caloric Restriction Through P53-Dependent Induction of GDF-15

Innovation in Aging ◽

10.1093/geroni/igaa057.413 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

pp. 125-126

Author(s):

Michael MacArthur ◽

Sarah Mitchell ◽

Jon Jung ◽

Margaret Torrence ◽

Alice Kane ◽

...

Keyword(s):

Food Intake ◽

Molecular Mechanisms ◽

Ex Vivo ◽

Brain Regions ◽

Target Tissue ◽

Dependent Manner ◽

P53 Signaling ◽

P53 Activation ◽

Visceral Adipose

Abstract MetAP2 is a 67kDa protein which sits at the translation initiation complex and cleaves N-terminal methionine off of nascent peptides. Inhibitors of MetAP2 cause profound weight loss secondary to decreased food intake. These inhibitors also significantly extend longevity in mice in late-life intervention. However, the exact mechanism of action causing decreased food intake is not known. Here we investigated the molecular mechanism and target tissue of a MetAP2 inhibitor’s (Zgn1062) anorectic effects. First we identified the target tissue by testing targeted Zgn1062 delivery to specific brain regions. Delivery to the medio-basal hypothalamus did not have a significant effect but delivery to the lateral ventricle resulted in significantly decrease food intake and body weight after 2 and 14 hours. When we delivered a neuron-targeted AAV encoding MetAP2 shRNA we saw decreased efficacy of MetAP2 confirming the required for neuronal MetAP2 for anorectic effects. To determine the molecular mechanisms we performed RNAseq of wildtype and MetAP2 KO HT1080 cells across a timecourse of Zgn1062 treatment. The main pathway activated across timepoints in MetAP2-dependent manner was P53 signaling. A main P53 target that was upregulated was the known anorectic peptide GDF15. We confirmed GDF15 increases in vivo at both mRNA (liver and intestines) and protein level (serum) in response to Zgn1062. We also found that Zgn1062 treatment reduces senescent cell burden in visceral adipose tissue in vivo and reduces SASP gene expression in fat explants ex vivo. We hypothesize that Zgn1062’s potent P53 activation may play a role in clearance of senescent cells.

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