bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ectoderm specific deletion of Jak2 results in developmental and neuronal abnormalities (1121.4)
Authors: Park Sung , Wagner Kay‐Uwe , Sayeski Peter 
Published: June 2021

Janus kinase 2 (Jak2) is a non‐receptor tyrosine kinase that is expressed in a number of mammalian tissues. Within the central nervous system, Jak2 has been associated with neuroproliferation, glial differentiation, synaptic plasticity, energy homeostasis, brain tumors, and neurodegenerative disorders. Recent clinical studies that have used Jak2 inhibitor therapy for the treatment of hematological disorders have noted an adverse event in the form of neuropathies in various ectoderm derived sensory organs as well as confusional states of mind. However, the precise physiological/patho‐physiological roles that Jak2 plays in ectodermal derived organs is not clear. Here, we hypothesized that Jak2 plays a critical role in the development of the ectoderm in mice. To test this, we created a tissue specific knockout mouse that lacks Jak2 in ectodermal derived organs. When compared to wild type littermate controls, these mice have a number of abnormalities in their reproductive organs, eyes, and digits. In addition, the mice had a marked alopecia and a behavioral disorder characterized by aimless and repeated circling within the cage. Interestingly, the penetrance of phenotypes was observed in 30% ‐ 50% of the homozygous mutant mice, thereby suggesting a role for other modifiers in these abnormalities. Collectively, these results indicate that Jak2 plays a critical role in the development of the mammalian ectoderm. Furthermore, because of the current use of Jak2 inhibitors in humans, these mice can serve as a valuable research tool for investigating neurotoxicity that is secondary to the loss of Jak2 function in ectoderm tissues.Grant Funding Source: Supported by NIH and AHA
NHE8 in human conjunctival epithelial cells: expression and regulation (1122.3)
Authors: Zhao Yang , Li Jing , Wang Mingwu , Ghishan Fayez , Xu Hua 
Published: June 2021

Dry eye disease (DED) is a disorder of the tear film by symptoms of dryness and irritation. Although the pathogenesis of dry eye is not fully understood, it is recognized that inflammation plays prominent role in the development and propagation of the debilitating condition. We have showed previously that loss of NHE8 function in mice resulted in dry eye syndrome. Therefore, we wanted to know if inflammatory cytokines (IL‐1β, IL‐6, IL‐17A and TNF‐α) which are detected in dry eye patients regulate NHE8 expression in the conjunctival tissue. Our results showed that NHE8 protein abundance was dramatically reduced in cells exposured to IL‐6, IL‐17A and TNF‐α in human conjunctival epithelial cells. The reduction on NHE8 protein expression was likely through inhibition of NHE8 mRNA expression in the case of IL‐1β, IL‐17A and TNF‐a. In summary, our study suggested that inflammatory cytokines regulate NHE8 expression at both protein and mRNA levels in dry eye condition.Grant Funding Source: Supported by NIH grant R01DK073638
Ethanol metabolite increases activity of CeA neurons and requires activation of local NMDA receptors (1125.5)
Authors: Chapp Andrew , Larson Robert , Huber Michael , Carter Jason , Chen Qing‐Hui 
Published: June 2021

The central nucleus of amygdala (CeA) is involved in the sympathoexcitatory and pressor responses to ethanol intake. However, the underlying neural mechanisms have not been determined. Here we investigated the role of acetate, the ethanol metabolite, in regulating the in vitro excitability of CeA neurons with axon projecting to rostral ventrolateral medulla (CeA‐RVLM) under brain slice preparation. In current‐clamp recordings, graded current injections evoked graded increases in spike frequency. Maximum discharge was evoked by +250 pA injections and averaged 18 ± 1 Hz (n=7). Bath application of acetate (0, 7.5, 37.5 and 75 mM) increased the excitability of CeA‐RVLM neurons in a dose‐dependent manner. Maximum spike discharge in the presence of acetate (75 mM) was 53 ± 3 Hz (n=4), which was significantly (p<0.01) higher than vehicle control. Pre‐treatment with AP5 (60 µM, n=7), the NMDA receptor blocker, significantly prevented increase in excitability (37 ± 5 Hz, p<0.05) elicited by acetate. AP5 alone was without effect on baseline excitability. The contribution of acetate in regulating sympathetic nerve activity (SNA) was assessed by microinjecting acetate into the CeA of anesthetized rat. Acetate (0.2 µmol/100 nl) significantly (P<0.05) increased lumber SNA by 90 ± 1 %, splanchnic SNA by 76 ± 18% and MAP by 4 ± 1 mmHg (n=3). Immunohistochemistry study demonstrates expression of NMDA NR1 in CeA‐RVLM neurons. Our data indicate that activation of NMDA receptors by acetate contributes to the increased excitability of CeA‐RVLM neurons. The CeA acetate elicited sympathoexcitatory responses involve the activation of CeA‐RVLM neurons, which may underlie the mechanisms of increased SNA during the development of alcohol associated hypertension.Grant Funding Source: Supported by AHA 10SDG2640130
α7 Nicotinic acetylcholine receptors induced an increase in intracellular calcium in supraoptic nucleus neurons (1126.20)
Authors: Song Zhilin 
Published: June 2021

The SON neurons synthesize oxytocin (OT) and vasopressin (VP) and receive cholinergic innervations. AchRs are expressed in SON. Activation of AchRs has been implicated in the control of water loss via VP release and also regulates release of OT, an anorexic agent. Deficits in OT are associated with human obesity. Thus, the brain cholinergic system may regulate food intake via modulation of OT neurons. Previous studies have demonstrated that activation of nAchRs stimulated a rise in [Ca++]i in SON neurons. In our current studies, live‐cell calcium imaging was used to determine the subtypes of nAchRs responsible. Mouse hypothalamic explants that include SON were loaded with the calcium sensitive dye, Fura‐2AM. Changes in [Ca++]i were monitored by changes in the 340/380 nm emission. Ach (5 mM) induced a [Ca++]i rise in the absence or presence of atropine (10 μM, muscarinic AchR antagonist) in wild type (WT) mice. In the presence of atropine, the amplitude of the [Ca++]i rise was reduced in WT mice while in α7 nAchR knockout (KO) mice, Ach only generated a small increase in [Ca++]i. Furthermore, in the additional presence of DHPE, an antagonist for α4β2 nAchRs, the rise in [Ca++]i in KO mice was completely absent. These experiments demonstrated that in SON neurons, both α7 and α4β2 nAchRs are functionally present and upon activation, generate calcium signals. Future studies will identify the OT vs VP phenotype of the responsive neurons.Grant Funding Source: Supported by a NORC pilot award from NIH DK048250.
Brain‐derived neurotrophic factor exerts depolarizing effects on hypothalamic paraventricular nucleus neurons (1126.6)
Authors: McIsaac William , Ferguson Alastair 
Published: June 2021

Brain derived neurotrophic factor (BDNF) is a chemical messenger that has been implicated in the central control of food intake and regulation of the stress axis. Consistent with a role in feeding behavior, TrkB, the receptor through which BDNF exerts its effects, is expressed in the PVN along with its low affinity receptor p75. Considering the paraventricular nucleus (PVN) of the hypothalamus is well established as a critical homeostatic relay center involved in the regulation of both of these systems, we investigated BDNF’s effects on the excitability of PVN neurons. Whole cell current‐clamp experiments were implemented to record from PVN neurons (N=23) in a hypothalamic slice preparation. BDNF dimer was bath applied at a concentration of 2nM for 2 minutes and elicited almost exclusively depolarizing effects (N=15) with a mean depolarization of 10.5 ± 1.74 mV. Cells responding to BDNF typically showed a return to baseline membrane potential within 200 seconds, although occasionally recoveries were not observed until 4000 seconds after application of BDNF. The results presented further elucidate the putative role of BDNF in feeding and regulation of the stress axis through its actions on PVN neurons.Grant Funding Source: Canadian Institutes of Health Research
Neuropeptide Y signaling from the hypothalamus inhibits sympathetic outflow to brown adipose tissue through GABA inhibition of the rostral medullary raphe (1126.8)
Authors: Nakamura Yoshiko , Nakamura Kazuhiro 
Published: June 2021

The arcuate nucleus is a central area involved in the regulation of metabolic thermogenesis in peripheral organs including brown adipose tissue (BAT). However, the efferent pathways from this nucleus for metabolic regulation are unknown. Activation of neuropeptide Y (NPY) neurons in the arcuate nucleus results in lowered metabolism likely through their direct projection to the paraventricular hypothalamic nucleus (PVH). In this study, we tested the hypothesis that NPY‐triggered neural signaling from the PVH inhibits sympathetic premotor neurons in the rostral medullary raphe (rMR) that control BAT thermogenesis. Sympathetic nerve activity and temperature in interscapular BAT were recorded in anesthetized rats, whose trunk was covered with a water jacket to control the skin temperature. Skin cooling‐evoked increase in BAT thermogenesis was eliminated by injection of NPY into the lateral ventricle or PVH. NPY injection into the PVH also eliminated BAT thermogenesis evoked by glutamate receptor stimulation in the rMR with an NMDA nanoinjection. On the other hand, NPY injection into the PVH did not affect BAT thermogenesis evoked by antagonizing GABA receptors in the rMR with a bicuculline injection. These results suggest that NPY signaling from the PVH activates a GABAergic inhibitory drive to sympathetic premotor neurons in the rMR to attenuate BAT themogenesis, leading to reduced energy expenditure.Grant Funding Source: Supported by NEXT Program and by Grants‐in‐Aid for Scientific Research, MEXT, Japan
Sustained hypoxia alters expression and function of excitatory amino acid transporters in the nucleus of the solitary tract (1127.2)
Authors: Matott Michael , Schramm Christine , Dantzler Heather , Kline David 
Published: June 2021

Glutamate is the major excitatory neurotransmitter in the brain. Its removal occurs via excitatory amino acid transporters (EAATs) located on glia (EAAT1 &amp; 2) and neurons (EAAT3 &amp; 4). This removal is important in normal synaptic functioning as well as in pathological conditions. The goal of this study was to determine the molecular and functional changes in glial EAATs in the nTS due to sustained hypoxia (SH). Male Sprague‐Dawley rats (4‐7 weeks) were exposed to 1 or 3 days of SH (10% O2) and compared to normoxic (N) controls. The nTS was harvested for quantitative real‐time PCR, immunohistochemistry and immunoblots to evaluate expression of EAAT1 &amp; 2. To examine EAAT function, nTS slices were made for whole‐cell electrophysiological recordings. EAAT1 and 2 in the nTS was confirmed by RT‐PCR, immunoblot and immunohistochemistry. EAAT2 mRNA was greater than EAAT1 in N, 1 and 3 d SH. One day SH did not alter EAAT 1 &amp; 2 RT‐PCR, immunoblots and immunohistochemistry. 3 d SH did not alter EAAT1 RT‐PCR or immunoblots, but increased EAAT2 mRNA with a trend for increased protein. Functionally, blockade of EAAT2 with dihydrokainate (DHK, 300µM) produced a significant inward current and depolarization of membrane potential. These effects were reduced in slices from 3‐days SH but not 1‐day SH. These data suggest that SH alters the expression and function of EAAT2 which may have a nueroprotective effect.Grant Funding Source: Supported by: RO1 HL098602
Nesfatin‐1 influences the excitability of subfornical organ neurons through actions on the Ik conductance (1129.2)
Authors: Kuksis Markus , Ferguson Alastair 
Published: June 2021

Nesfatin‐1 is produced in several brain areas involved in metabolic processes and has been implicated in the control of ingestive behaviors and cardiovascular function. In this study, we confirm the presence of mRNA for the nucleobindin‐2 gene in the subfornical organ (SFO). We used whole‐cell patch clamp recordings in current clamp configuration to investigate the influence of nesfatin‐1 on the membrane potential of dissociated SFO neurons. We found that 80.3% (49 of 61) of neurons tested showed a response to nesfatin‐1 (100 nM, 10 nM and 1 nM) with 47.5% depolarising and 32.8% hyperpolarising. We then used voltage clamp configuration to investigate the conductances through which nesfatin‐1 may act to change the membrane potential of SFO neurons. Voltage clamp ramp and step protocols revealed a nesfatin‐1 induced enhancement of the delayed rectifier potassium conductance, IK. Pharmacological blockade of this conductance using tetraethyl ammonium chloride (TEA) greatly reduced the magnitude and occurrence of the observed hyperpolarisations, which implies that nesfatin‐1 induced hyperpolarisations are mediated through IK. This study has demonstrated that nesfatin‐1 has the ability to influence the membrane potential of SFO neurons by enhancing the IK conductance, and thus has identified the SFO as a potential site at which nesfatin‐1 may act to regulate ingestive behaviour and cardiovascular control.Grant Funding Source: Canadian Institutes for Health Research
Effect of liposome entrapped‐GABA on the expression of nNOS and GABAA receptors in neurons (1130.11)
Authors: Vaz Gisele , Sharma Neeru , Zheng Hong , Bahia Ana Paula , Zimmerman Matthew , Frezard Frederic , Fontes Marco , Patel Kaushik 
Published: June 2021

Liposomes are concentric lipid vesicles that allow a sustained release of entrapped substances. GABA is the most prevalent inhibitory neurotransmitter in the central nervous system. Here we determined the effect of sustained release of GABA on the expression of neuronal nitric oxide synthase (nNOS) and GABAA receptor (GABAAR) in a neuronal culture (NG108‐15 cells). GABA entrapped‐liposomes particles (GEL) were prepared by the freeze‐thawing method. In vitro studies using NG108‐15 neurons treated with different doses of GEL for 12 hr showed an increase in nNOS (138, 157 and 165% at doses of 20, 50 and 100 ng respectively) and GABAAR (54 and 50% at the doses of 10 and 20 ng respectively) compared with control. Moreover, we found a decreased expression of protein inhibitor of nNOS (PIN) with GEL treatment (26, 66 and 57% at doses of 20, 50 and 100 ng, respectively). Time course experiments in cells treated with 50 ng of GEL, showed an increase in GABAAR (23%) after 1 hr followed by an increase in nNOS (55, 46 and 55%) and decrease in PIN (22, 28 and 53%) at 8, 12, 24 hr, respectively. Immunostaining also showed an increase in nNOS expression (134%) in cells after 12 hr of GEL treatment. These results suggest that the slow release of GABA can change the expression of nNOS in neuronal cultures, potentially by altering the expression of PIN. Supported by NIH grants HL62222 &amp; DK82956 &amp; CNPq fellowship to GCV.Grant Funding Source: NIH grants HL62222 & DK82956 & CNPq fellowship to GCV
Blockade of mineralocorticoid receptors in the dorsal hindbrain inhibits stress‐induced hypertension in rats (1130.12)
Authors: Clifton Rebekah , Backes Iara , Scheuer Deborah 
Published: June 2021

This study tested the hypothesis that chronic blockade of mineralocorticoid receptors (MR) in the dorsal hindbrain (DHB) attenuates cardiovascular responses to stress in male Sprague‐Dawley rats subjected to chronic variable stress (CVS) for 2 weeks. Blood pressure was measured using radiotelemetry. Baseline data were collected for 1 wk then all rats were given a continuous choice of water or 0.3M NaCl to drink, and pellets made of cholesterol (Chol) or the MR antagonist spironolactone (SPL) were implanted over the DHB. Rats were then subjected to CVS or remained unstressed (n=4‐6/group). Baseline blood pressure averaged 95±1 and 99±1 mmHg during the light (L) and dark (D) periods respectively. During the last week, CVS significantly (P<0.05) increased baseline blood pressure in the Chol + stressed (∆8±2 (L) and 9±3 (D) mmHg) but not in the SPL + stressed rats (∆1±1 and 1±1 mmHg). Blood pressure was not changed in the unstressed Chol (∆1±2 mmHg and ∆3±2) or SPL (∆‐1±1 and ∆1±1 mmHg) rats. SPL significantly attenuated the arterial pressure response to a novel cage stress, but not to other stressors. The results suggest that chronic blockade of DHB MR can eliminate stress‐induced hypertension.Grant Funding Source: NIH #HL076807, AHA #GRNT4460047
Acute intermittent hypoxia induces sympathetic long‐term facilitation but does not alter synchronization between phrenic and sympathetic nerves (1130.15)
Authors: Yamamoto Kenta , Lalley Peter , Mifflin Steve 
Published: June 2021

Acute intermittent hypoxia (AIH) can induce phrenic and sympathetic long‐term facilitation (LTF). Respiration modulates the sympathetic nervous system, leading to an idea that respiratory‐sympathetic coupling plays a role in the generation of sympathetic LTF. To determine if augmentation of synchronization between phrenic and sympathetic nerve activities is necessary to generate sympathetic LTF, we investigated the effect of AIH on phrenic nerve activity (PNA) and renal sympathetic nerve activity (RSNA) using spectral analysis in anesthetized, vagotomized and artificially ventilated Sprague‐Dawley rats (n=6). AIH was performed by ventilation with 10% oxygen for 1min every 6min for a total of 10 hypoxic exposures within an hour. PNA amplitude and RSNA increased by 110% and 100% respectively measured 60 min after AIH (P<0.05). We estimated spectral power of PNA and RSNA and coherence between PNA and RSNA at central respiratory drive frequency, defined as frequency of the main peak in PNA. Spectral power of PNA and RSNA increased by 640% and 270% respectively measured 60 min after AIH (P<0.05). However, coherence between PNA and RSNA did not change from baseline (0.62 +/‐ 0.34) to 60 min after AIH (0.71 +/‐ 0.25). These results suggest that AIH can induce sympathetic LTF in the absence of augmented synchronization between central respiratory drive and RSNA.Grant Funding Source: HL088052
HIF‐1α increases sympathoexcitation via upregulation of NMDA receptors in the PVN during heart failure (1130.16)
Authors: Sharma Neeru , Cunningham Craig , Liu Xuefei , Zheng Hong , Patel Kaushik 
Published: June 2021

Increased sympathetic outflow is a prominent feature of chronic heart failure (HF) associated with higher mortality. Multiple studies from our lab have reported that higher glutamatergic tone (increase in N‐methyl‐D‐aspartate (NMDA)‐type 1 (NR1) receptors expression) within the paraventricular nucleus (PVN) increase the sympathetic drive in HF. Further, HF (coronary artery ligation‐induced) augmented the expression of hypoxia‐inducible‐factor (HIF)‐1α both at mRNA (9 fold) and protein (2.5 fold) levels in the PVN which, led us to hypothesized that increased levels of HIF‐1α may contribute to exaggerated sympathetic drive via increasing NR1 expression in the PVN of rats with HF. Neuronal cell line (NG108‐15) exposed to hypoxia (2% O₂, 5% CO₂, 93% N₂) showed 2‐fold increase in HIF‐1α (12h) expression with concomitant increases in NR1 at transcription and protein levels after 4h (6.5 fold) and 12h (40%) respectively. Live cell imaging also showed marked increase in intracellular calcium in response to glutamate under hypoxic conditions. Mechanistically, hypoxia promotes the direct binding of HIF‐1α (3.2 fold) at NR1 promoter in neurons exposed to hypoxia as demonstrated by chromatin immunoprecipitation analysis. Furthermore, silencing of HIF‐1α by using HIF‐1α ‐targeted small interfering RNA in neurons led to 2.9 fold decrease in the expression of NR1. Validating our in vitro data, HIF‐1α knockdown by HIF‐1α‐siRNA in the PVN of rats with HF ameliorated the increased sympathoexcitation to NMDA (57±5% vs. 27±1% of basal value). Taken together, our study suggests a contribution of HIF‐1α in the regulation of NR1 expression within the PVN in HF, and provides a novel mechanism for the modulation of sympathoexcitation in HF. Supported by NIH HL62222.Grant Funding Source: NIH HL62222.
RVLM sympathetic premotor neurons are not synaptically linked to each other (1130.17)
Authors: Bou Farah Lama , McMullan Simon 
Published: June 2021

Sympathetic premotor neurons residing within the rostral ventrolateral medulla (RVLM) control the activity of sympathetic nerves and blood pressure. In vivo, the activities of sympathetic nerves and spinally projecting cells in the RVLM display rhythmic bursting that is independent of baroreceptor input. We have previously proposed that such synchronisation could result from functional coupling between spinally projecting neurons.In this study we directly test that hypothesis by examining the prevalence of synaptic connections between pairs of RVLM sympathetic premotor neurons, identified by retrograde transport of tracer microinjected into the spinal cord.We simultaneously recorded membrane voltage and currents in pairs (34 pairs from x neurons) of bulbospinal neurons recorded in whole cell mode in acute brainstem slices prepared from P8 ‐ P20 rats. We injected depolarizing currents to evoke trains of action potentials in the ‘presynaptic’ neuron and used ‘presynaptic’ action potentials to trigger averages of holding current recorded in the ‘post‐synaptic’ neuron.No evidence of monosynaptic connections was observed in any case, despite long and stable recordings from neurons in close proximity to one another. We conclude that direct synaptic connections between bulbospinal neurons are sparse or non‐existent and that direct connections between these cells toes not play a significant functional role.
A nigro‐vagal pathway controls gastric motility (1130.18)
Authors: Toti Luca , Travagli R. Alberto 
Published: June 2021

Degeneration of dopaminergic (DA) neurons of the substantia nigra pars compacta (SNpc) induces Parkinson’s disease (PD). Since almost all patients with PD show gastrointestinal (GI) dysfunctions, such as gastroparesis, and GI functions are controlled by neurons in the dorsal motor nucleus of the vagus (DMV), we aimed to determine whether manipulations of the SNpc induces a vagally‐mediated modulation of gastric motility.Microinjection of the retrograde tracer CTB in the DMV labelled neurons in the SNpc, indicating a monosynaptic nigro‐vagal complex connection.In an anesthetized rat preparation in which gastric motility was recorded using miniaturized strain gauges sewn on the anterior stomach wall, NMDA was microinjected in the left SNpc (210nL of a 25mM). In control rats, NMDA increased tone and motility in both the corpus and in the antrum (tone: +211±37, N=11 and +295±53 mg, N= 8; motility: +85±21, N=9 and +82±19%, N=9, of baseline, respectively). This effect was blocked by ipsilateral vagotomy (N=4) or by application to the fourth ventricle of DA‐1 (SCH‐23,390, 45nM) and DA‐2 (L‐741,626, 45nM) antagonists (N=4). In contrast, following microinjection of 6OH‐DA in the SNpc, application of NMDA had no effect on gastric motility (N=4).Our data indicate a monosynaptic connection exists between the SNpc and DMV that modulates gastric tone and motility, suggesting a novel pathway in the regulation of GI functions which may be compromised in PD.Grant Funding Source: DK55530