bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insulin‐dependent Decrease of Excitatory Neurotransmission in Preautonomic PVN Neurons Is Reduced in Diet‐induced Obese Mice
Authors: Molinas Adrien Jacques Raymond , Desmoulins Lucie Delphine , Gao Hong , Zsombok Andrea 
Published: June 2021

The liver plays a crucial role in the maintenance of glucose homeostasis and evidence supports a governing role for the autonomic nerves in regulating hepatic functions. Activation of hepatic sympathetic nerves increases hepatic glucose production and glycogenolysis; while activation of parasympathetic nerves decreases glucose production and promotes glucose storage. Moreover, excessive hepatic glucose production is a major contributor to hyperglycemia; however, the neural mechanisms underlying the elevated glucose production remain to be determined. In this study, we tested the hypotheses that 1) insulin decreases excitatory neurotransmission in liver‐related neurons in the paraventricular nucleus (PVN), and 2) the insulin‐dependent decrease of excitatory neurotransmission is reduced in pre‐sympathetic PVN neurons in diet‐induced obese (DIO) mice. First, liver‐related PVN neurons were identified with a retrograde, trans‐synaptic viral tracer and whole‐cell patch‐clamp recordings were conducted in male C57BL/6J mice. Bath application of insulin (1μM) decreased the frequency of miniature excitatory post‐synaptic currents (mEPSCs) in liver‐related PVN neurons (1.4±0.3 Hz vs. 1.0±0.2 Hz, n=6, paired t‐test p=0.002). Then, the effect of insulin was determined on excitatory synaptic currents in pre‐sympathetic PVN neurons in male control and DIO mice. In 16‐week‐old control mice, insulin decreased the frequency of mEPSCs (1.6±0.5 Hz vs. 1.3±0.4 Hz, n=10, paired t‐test, p=0.008); whereas, in age‐matched DIO mice insulin failed to decrease mEPSC frequency (1.8±0.4 Hz vs. 1.8±0.5 Hz, n=8). Next, we used channel rhodopsin‐assisted circuit mapping to identify the origin of inputs to liver related PVN neurons. PVN receives inputs from key nuclei implicated in glucose metabolism, including the dorsomedial, ventromedial and the arcuate nucleus; therefore, a viral construct (rAAV5‐hSyn‐hCHR2(H134R)‐mCherry) was injected to the mediobasal hypothalamus (MBH) and light evoked currents were recorded from liver‐related PVN neurons. Light stimulation of ChR2‐expressing fibers in the PVN revealed that one third of the recorded liver‐related PVN neurons received inputs from the MBH. Together, our data demonstrate that excitatory neurotransmission to liver‐related PVN neurons and to pre‐sympathetic PVN neurons is regulated by insulin and this insulin‐dependent suppression is diminished in DIO mice. We also revealed that a subset of liver‐related PVN neurons receives inputs from the MBH. In summary, our findings suggest synaptic plasticity and altered autonomic circuits at the level of the hypothalamus, which likely contributes to dysfunctional autonomic regulation of the liver in diet‐induced obesity.Support or Funding InformationNIH R01 DK099598This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Acute neurosteroid treatment with allopregnanolone enhances dorsal vagal motor neuron inhibition
Authors: Littlejohn Erica , Boychuk Carie 
Published: June 2021

Neurons in the dorsal motor nucleus of the vagus (DMV) comprise the preganglionic parasympathetic motor output to much of the viscera and critically contribute to autonomic regulation of energy homeostasis. DMV neuron function is tightly regulated by gamma‐aminobutyric (GABA) input to GABAA receptors, which inhibits neuronal excitability. Extrasypnatically localized GABAA receptors, primarily containing δ‐subunits, respond to ambient GABA, setting the tonic inhibitory tone in DMV neurons. Allopregnanolone is a centrally and peripherally produced neuroactive steroid metabolite which readily crosses the blood brain barrier and is a potent allosteric activator of GABAA receptors. Outside of the DMV, allopregnanolone has been shown to increase inhibitory tonic current in a GABAA‐δ dependent manner. DMV neurons have significant tonic inhibition. These currents are largely mediated by the GABAA receptors containing the δ‐subunit. However, no studies to date have investigated the potential for allopregnanolone to induce changes in GABAergic signaling to DMV neurons. Therefore, we hypothesized that acute allopregnanolone exposure increases GABAA receptor mediated inhibition in DMV neurons through a GABAAR δ‐subunit dependent manner. To test this hypothesis, we incubated brainstem slices in allopregnanolone (100nM) or vehicle containing artificial cerebral spinal fluid (ACSF) for 30 minutes. We then analyzed GABAA receptor mediated inhibition in DMV neurons at 30, 60, and 120 minutes following the completion of this incubation. We examined both modalities of GABAA receptor inhibition, phasic and tonic using the specific GABAA antagonist bicuculline (BIC) and wholecell patch‐clamp electrophysiology. Allopregnanolone treatment increased most measures of inhibition in DMV neuron at 30 minutes, including spontaneous inhibitory postsynaptic current (sIPSC) decay time and BIC‐sensitive tonic current. DMV neurons from slices incubated in either allopregnanolone or control ACSF were probed for choline acetyltransferase and GABAA‐δ subunit expression using immunohistochemistry. Brief exposure to allopregnanolone transiently potentiates GABAA receptor response to ambient GABA. Allopregnanolone may play an important role in dynamically modulating vagal inhibition in models of disease.Support or Funding InformationAmerican Heart Association Grant# 16SDG26590000 and NIH Grant# 5T32HL007446‐37This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Does Estrogen Act as a Neuroprotective Agent on In Vitro‐Induced β‐Amyloid Plaques in N38 Hypothalamic Neuronal Cells?
Authors: Yakubov Rakhsim , Almathhur Rayan , Suh Catherina , Yoon Jihyung , Cooperstein Deborah , Chakraborty Sanjoy , Chakraborty Tandra R 
Published: June 2021

A key characteristic of Alzheimer's disease (AD) is the deposition of beta‐amyloid fibrils in extracellular plaques, as well as the intracellular accumulation of tau in neurofibrillary tangles in the brain. This study is designed to induce plaques on N38 hypothalamic neuronal cells under in vitro conditions using synthetic beta‐amyloid and subsequently to treat with estrogen as a neuroprotective reagent. The cell viability, toxicity and proliferation were determined using different bioassays like cell count, Congo red, MTT and lactate dehydrogenase assay. Results indicate a significant loss in cell death, amyloidosis, mitochondrial dysfunction and increased cytotoxicity in cells treated with beta‐amyloid and neuroprotection when exposed to estrogen. Further, in order to understand the mechanism by which neuronal death by plaque formation and neuroprotection by estrogen western blotting was performed to determine the changes associated with biomarker Tau protein. Taking together the biochemical and molecular data, the neuroprotective effect of estrogen on beta amyloid plaque formation will be analyzed.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Central Circuits Inhibiting Skeletal Muscle Shivering
Authors: Morrison Shaun F. , da Conceição Ellen Paula Santos 
Published: June 2021

BackgroundSkeletal muscle shivering is the most important source of thermogenesis in the human cold‐defensive maintenance of core body temperature (Tcore) and the elevated Tcore during fever. We have described the thermoregulatory reflex pathway through which skin and core cooling, or injection of prostaglandin E2 into the preoptic area of the hypothalamus, leads to activation of skeletal muscle shivering (J Physiol 589.14: 3641–3658, 2011). Here we describe brain regions containing neurons that can provide an inhibitory regulation of shivering.ResultsEMG activities in masseter, neck and gastrocnemius muscles were recorded in Inactin‐anesthetized rats during cold exposure or injection of PGE2 into the preoptic hypothalamus. Cold‐evoked and febrile shivering EMGs were eliminated by activation of neurons in the ventral part of the lateral preoptic nucleus (vLPO), or by increasing the discharge of neurons in the paraventricular hypothalamus, in the nucleus of the tractus solitarii, or in the ventrolateral medulla. Inhibiting neuronal discharge or blocking glutamate receptors in the vLPO elicited a sustained increase in shivering EMGs in warm rats.ConclusionThese results indicate the strong, tonic inhibitory influence of neurons in the vLPO on skeletal muscle shivering, likely through a GABAergic input to shivering premotor neurons in the rostral raphe pallidus. The discovery of the vLPO and other neuronal populations capable of inhibiting shivering supports the potential for the therapeutic control of shivering in the settings of neurogenic fever, brain injury, or induction of hypothermia.Support or Funding InformationSupported by NIH grants NS040987 and NS091066This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Neural Responses of the Cervical Sympathetic Chain to Barorecepter Activation and to Hypoxic Challenge in Sprague‐Dawley Rats
Authors: Muntzel Martin , Lewis Stephen , Hsieh Yee‐Hsee 
Published: June 2021

The superior cervical ganglion (SCG) and cervical sympathetic chain (CSC) contain cell bodies that project to the cerebral arteries, and to peripheral structures such as the carotid bodies and upper airways. Despite the importance of these pathways, little is known about how the CSC responds to baroreceptor stimuli and to hypoxic challenges that mimic upper airway obstruction and central apneas. To characterize sensory control of CSC activity, we anesthetized male Sprague‐Dawley rats (275–300g) with isoflurane (2%) and placed bipolar recording electrodes under the CSC at approximately 3 mm caudal to the SCG, and a blood pressure catheter into the left femoral artery (Telemetry Research, model TR56SP). A catheter was placed in the left femoral vein for intravenous (IV) injections. Heart rate, blood pressure (BP), and multi‐fiber CSC neural activity were recorded during 10% oxygen challenge, tracheal occlusion, and during IV drug administration. At the end of the protocol, the rats were euthanized to determine background noise activity. In on‐going studies (n = 4), we found that CSC recordings yielded typical sympathetic responses to phenlyephrine (2.5 μg) and sodium nitroprusside (2.5 μg). For phenyephrine, BP increased by 24 ± 5 mmHg with CSC decreases of 100% baseline to 69 ± 11%. For sodium nitroprusside, BP decreased by 26 ± 3 mmHg with CSC increases of 100% to 111 ± 14%. Ganglionic blockade with hexamethonium (10 mg/kg) decreased BP by 49 ± 2 mmHg and lowered CSC activity by 69 ± 8%. Temporary occlusion of the tracheal airway decreased BP by 16 ± 4 mmHg and increased CSC activity from 100% to 120 ± 17%. Finally, a 1 min 10% oxygen challenge lowered BP by 33 ± 9 mmHg but did not alter CSC activity (100% to 103 ± 5%). These findings indicate that the CSC, just caudal to the SCG, contains approximately 69% post‐ganglionic sympathetic nerve fibers. These nerve fibers respond appropriately to baroreceptor loading and unloading, and show increased activity to temporary upper airway occlusion.Support or Funding InformationThis work was supported in part by NIH award 3OT2OD023680‐01S2 and Galvani BioelectronicsThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cellular Senescence in the Rostral Ventrolateral Medulla (RVLM) – Novel Implications for Obesity‐Induced Sympathoexcitation
Authors: Subramanian Madhan , Csiszar Anna , Ungvari Zoltan , Balasubramanian Priya 
Published: June 2021

Oxidative stress in the RVLM, a key brainstem region that regulates sympathetic nerve activity (SNA) and blood pressure has been associated with obesity‐induced hypertension. Chronic oxidative stress is a known stimulus for induction of cellular senescence, a state of irreversible growth arrest in proliferating cells. Senescent cells are also a potential source of neuroinflammation as they secrete cytokines, chemokines and proteases through acquisition of senescence‐associated secretory phenotype (SASP). Whether obesity induces senescence in the brainstem to promote neuroinflammation and increases in SNA is not clear. Hence, we hypothesized that obesity triggers the induction of cellular senescence in the RVLM, which in turn contributes to neuroinflammation and increases in SNA leading to the development of hypertension. To address this hypothesis, 2 months‐old male C57BL/6J mice were fed a high‐fat diet (HFD; 60% fat; n=5) or normal chow diet (Controls;10% fat; n=5) for 16 weeks. At the end of the dietary treatment, brainstem was isolated from the animals for assessment of senescence in the RVLM. Data were analyzed by unpaired students t‐test and expressed as mean ± SE. HFD treatment significantly increased the expression of senescence marker p16ink4a (1.15 ± 0.22 vs 2.17 ± 0.37, fold change, normal diet vs HFD, p<0.05), which is involved in cell cycle arrest. This was accompanied with SASP characterized by increased expression levels of cytokines and chemokines, namely IL‐1β (1.02 ± 0.09 vs 1.35 ± 0.05, p<0.05), MCP1 (1.03 ± 0.13 vs 1.48 ± 0.05, p<0.05) and TNFα (1.04 ± 0.15 vs 1.42 ± 0.09, p<0.05) compared to controls. In addition, the number of cells positive for senescence associated β‐galactosidase activity (SA‐β‐gal) was significantly higher in the RVLM of HFD animals compared to controls. In the next series of experiments, we utilized p16‐senescence reporter mice to investigate obesity‐induced senescence in the RVLM. These mice express red fluorescent protein (RFP) under the control of p16 promoter and hence senescent cells are genetically labeled with RFP expression. HFD treatment in p16‐reporter mice resulted in significant increases in the number of RFP positive cells in the RVLM, further confirming obesity‐induced senescence in the RVLM. Collectively, our results show for the first time, evidence for obesity associated cellular senescence in the RVLM. Future studies will characterize the cellular type and investigate the mechanistic role of senescence in the RVLM in obesity‐induced sympathoexcitation.Support or Funding InformationRAC fund, CVHS, Oklahoma State UniversityThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Sympathetic Neurotransmission in Resistance Mesenteric Arteries in Obesity‐Related Hypertension
Authors: Sangsiri Sutheera , Galligan James J 
Published: June 2021

Hyperactivity of sympathetic nerves has an important role in the pathogenesis of obesity‐related hypertension. The mechanisms linking obesity to hypertension are unclear. Small mesenteric arteries (MA, <300 mm dia.) are resistance blood vessels that are densely innervated by sympathetic nerves. Nerve varicosities release norepinephrine (NE) and ATP which cause arterial constriction. Impaired control of NE and/or ATP release and clearance would cause hypertension. Alterations in sympathetic nerves supplying MAs contribute to hypertension in several animal models. This study examined whether alterations of sympathetic neurotransmission in the resistance MAs contribute to high blood pressure in high fat‐fed (HF) Dahl salt‐sensitive rats. Sympathetic nerves supplying MAs maintained in vitro were stimulated focally. Electrically‐evoked NE and ATP release were detected by using amperometry with carbon fiber electrodes, and intracellular recording of excitatory junction potentials (EJPs) from arterial smooth muscle cells, respectively. Data were obtained from male and female rats at 10, 17, and 24 weeks of control and HF diet. Peak amplitudes of NE oxidation current and EJPs were assessed. NE oxidation current from all groups were blocked by a Na+ channel blocker, tetrodotoxin (TTX, 300 nM), suggesting that NE release in neurogenic. EJPs from all groups were abolished by TTX, and PPADS (10 μM), a P2X receptor antagonist, indicating that EJPs were neurogenic and purinergic. Frequency (1–30 Hz, 50 pulses) response curves using amperometric measurement of NE release showed similar responses in MAs from control and HF fed male and female rats. EJP frequency (0.5–10Hz, 5 pulses) response curves were also similar in MA from control and HF fed male and female rats. We investigated prejunctional α2‐adrenergic receptor function using the α2 receptor agonist (UK14,304) and antagonist (yohimbine). UK14,304 (0.0001–10 μM) inhibited NE and ATP release equally well and in a concentration‐dependent manner in MAs from control and HF rats. In the presence of 1 μM yohimbine, NE and ATP release was increased equally in MA from all rats. We conclude that adrenergic and purinergic neurotransmission by periarterial sympathetic nerves are not affected in HF Dahl salt sensitive rats. Elevated blood pressure in this animal model is not dependent on altered sympathetic neurotransmission to the mesenteric vasculature.Support or Funding InformationNIH 2P01HL070687 (For JJG), and Post‐doctoral training scholarship, Faculty of Medicine, Thammasat University, Thailand (For SS).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Characterization of claudin‐5, ‐2, occludin and PPAR alpha in a model of early diabetic nephropathy
Authors: Rosas Lorena , Rodríguez Rafael , del Carmen Namorado María , Reyes Jose Luis , Cervantes Luz Graciela 
Published: June 2021

The WHO estimates that there are more than 422 million people with diabetes in the world, of whom 90% are diagnosed as type 2. Hyperglycemia plays an important role in renal damage, thus diabetic nephropathy is the most common complication of this pathology. Claudins are components of paracellular transport which are determinants to the ion balance in the kidney. Any alteration in the tight junctions carry a pathophysiological renal consequences that have not yet described in diabetic type 2 model. PPARs are nuclear receptors ligand‐dependent and their alpha isoform is activated by fibrates. Pharmacological therapy with fibrates in diabetes had showed to prevent cardiovascular risk, if they have renal protective effects in diabetes and if they are involved in paracellular ion transport, is not well understood. Those actions, could be useful as a target to identify, prevent and treat diabetic nephropathy may contribute to a better understanding of this disease. Type 2 diabetes model that we used was induced to neonatal rats by the intraperitoneal administration of streptozotocin, a chemical that selectively destroys the β cells of the pancreas, diabetics rats showed moderate hyperglycemia since 4th week and at 14‐week, had a decrease in body weight gain, glucose intolerance, lower insulin secretion and an increase in renal mass. We evaluated renal function in this model and we observed that proteinuria was associated with a decrease in claudin‐5 expression in the glomerulus and the increased fractional excretion of Na+ and K+ was related with a decrease of claudin‐2 and occludin in the proximal tubule. In addition, we observed a loss of renal expression of peroxisome proliferator‐activated receptor alpha (PPAR‐α) in both segments of the nephron. The present work provides evidence that type 2 diabetes alters the renal expression of tight junctions proteins such as claudin‐5, claudin‐2 and occludin, as well as PPAR‐α. This is related to the loss of renal function, suggesting that the loss of these proteins is a fundamental part of the early stages of type 2 diabetic nephropathy.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Esm‐1 Protects Mice from Glomerular Macrophage Infiltration and Macroalbuminuria in Diabetic Nephropathy
Authors: Zheng Xiaoyi , Higdon Lauren , Sayed Nazish , Liu Chun , Wu Joseph , Maltzman Jonathan , Bhalla Vivek 
Published: June 2021

Diabetic nephropathy (DN) is the most common cause of kidney failure in the world, but only a minority of individuals with diabetes develop nephropathy. Extending this observation to mice, different mouse strains are susceptible or resistant to DN. In comparing glomerular transcriptome profiles, we published that DN‐susceptible mice up‐regulate pro‐inflammatory pathways and have diminished expression of endothelial cell‐specific molecule‐1 (Esm‐1) mRNA and protein. Esm‐1 is a secreted glycoprotein that is enriched within kidneys and specifically, in glomeruli. We now test the hypothesis that Esm‐1 over‐expression would inhibit inflammation and rescue DN‐susceptible mice and conversely, Esm‐1 deletion would promote nephropathy in DN‐resistant mice. We first confirmed that Esm‐1 is enriched in glomerular endothelial cells by single cell qPCR. Esm‐1 expression was restricted to Cdh5(+) or CD31(+) cells and absent in cells enriched for podocyte or mesangial cell markers. We demonstrate by flow cytometry that in diabetic mice, endogenous, plasma Esm‐1 inversely correlates with glomerular leukocyte infiltration (R2 = 0.61). Next, by hydrodynamic tail‐vein injection in DN‐susceptible mice, we increased circulating Esm‐1 and demonstrate diminished albumin‐to‐creatinine ratio vs. saline‐injected controls (1.0 ± 0.5 mg/mL vs. 3.6 ± 1.4 mg/mL, p = 0.008). Interestingly, over‐expression of non‐glycosylated Esm‐1 did not decrease albuminuria. In a corollary experiment, genetic deletion of Esm‐1 in DN‐resistant mice, increases urine albumin‐to‐creatinine ratio vs. wild‐type controls (806.5 ± 332.0 ug/mL vs. 1.4 ± 0.29 ug/mL, p < 0.001). In mechanistic studies, we previously published that Esm‐1 decreases leukocyte transmigration across endothelium in vitro. We now demonstrate by flow cytometry that increasing circulating Esm‐1 decreases glomerular macrophage infiltration (0.9 ± 0.5 % vs. 3.1 ± 0.7 % of total single cells, p = 0.002) in diabetic mice in vivo. Neutrophil and lymphocyte infiltration were not significantly different between groups. In conclusion, glycosylated Esm‐1, an endothelial cell‐specific inhibitor of leukocyte infiltration, protects mice from macroalbuminuria, possibly through inhibiting glomerular macrophage infiltration.Support or Funding InformationLarry L. Hillblom Foundation; Holmgren Family Fund; NIH/NIDDKThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.