bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex‐specific differences in emergence patterns of solitary, cavity‐nesting bee, Megachile rotundata
Authors: DeBardlabon Korie Michelle , Bennett Meghan M , Yocum George D , Rinehart Joseph P , Greenlee Kendra
Published: June 2021

Circadian rhythms play an important role in synchronizing biological processes. These rhythms are often influenced by semi‐predictable period cues, such as photoperiod or thermoperiod, often referred to as zeitgebers. The alfalfa leafcutting bee, Megachile rotundata, is a solitary, cavity‐nesting bee known to synchronize its emergence with thermoperiods as the dominant cue. Bees emerge as adults from brood cells. Brood cells are constructed by females with leaves and provisioned with pollen and nectar. One egg is laid in each brood cell, and a nest is composed of multiple brood cells in series in the cavity. Offspring go through all of juvenile development and metamorphosis in the cavity. It is unknown if certain variations in thermoperiod affects the timing of emergence. Because brood cells are built in series in the nest, adult offspring must emerge in a specific order to prevent bees placed at the back of the cavity from emerging before those in the front. If a bee in the back were to emerge first it would chew through its siblings' brood cells, potentially killing them, in order to exit the cavity. Thus, regulating emergence is important. On average, male M. rotundata are smaller than females, and often the brood cells at the front of cavities contain male offspring. Because of this, bee weight and sex are hypothesized to affect timing of emergence. To test this hypothesis, we disarticulated nests and placed individual brood cells in an apparatus that automatically records emergence time. We placed bees in various thermoperiods and recorded emergence time, sex, and dry weight of adult bees. It is well known that adult male offspring begin emerging days before females. In this study male offspring emerged earlier in the day than females which could be important for mating strategies. Understanding the roles sex and weight play in emergence and how these factors interact with different thermoperiods will help us to understand the maternal contribution to offspring development.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Orexin Receptor‐1 Inactivation Facilitates Lung Motor Activity during In Vitro Hypercapnic Stimulation of Pre‐metamorphic Bullfrogs
Authors: Janes Tara , Fonseca Elisa , Fournier Stéphanie , Gargaglioni Luciane , Kinkead Richard
Published: June 2021

The mechanisms regulating amphibian respiration change dramatically during development as the animal transitions from aquatic to aerial breathing. Gill ventilation is the primary mechanism for oxygen acquisition in early stages, but infrequent lung breaths also occur. Interestingly, activating central chemoreceptive pathways (i.e. hypercapnia, hypoxia) can stimulate lung motor activity in tadpoles. Yet, the mechanisms which modulate chemosensitivity at various stages of development remain poorly understood in amphibians. Orexin is a critical hypothalamic neurotransmitter that is highly conserved across vertebrates and regulates important functions including sleep‐wake states, feeding, and breathing. In many vertebrates, orexinergic neurons are profoundly excited by increased CO2 (and decreased pH), suggesting that they are intrinsically chemosensitive. We hypothesized that antagonism of the orexin receptor‐1 (OX1R) would blunt the increased ventilatory response to hypercapnia in pre‐metamorphic tadpoles of the American bullfrog (Lithobates catesbeianus). Using tadpole brainstem preparations (Taylor‐Kollros stages: IV–XII), we determined the effects of hypercapnia alone (5% CO2, 20 mins), or in the presence of an OX1R antagonist (SB‐334867, 10μM) on respiratory motor activity recorded from cranial nerves V, VII and X. Isolated brainstems were transected rostral to the optic nerve to maintain an intact hypothalamus. Contrary to previous reports performed on preparations without the hypothalamus, our data showed no significant effect of hypercapnia on the frequency of lung bursting in this stage group. However, blocking OX1R's during hypercapnia revealed a significant ventilatory response observable as an increase in lung burst frequency (baseline respiratory motor activity was not affected by SB‐334867). Although these results were contrary to our hypothesis, they demonstrate that orexin inhibits the central CO2 chemoreflex of pre‐metamorphic bullfrog tadpoles.

Support or Funding Information

This work was supported by the Emerging Leaders in the Americas Program and Fonds de Recherche de Quebec ‐ Nature et Technologies awarded to E. Fonseca. Additional support was provided by the Fonds de Recherche du Québec ‐ Santé (FRQS) for T. Janes and an NSERC Discovery Grant awarded to R. Kinkead.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
African Spiny Mice as a Comparative Model of Spinal Cord Injury Repair and Recovery
Authors: Orr Michael , Bailey William , Richards Kirsten , Kopper Timothy , Seifert Ashley , Gensel John
Published: June 2021

The adult mammalian central nervous system does not regeneration after injury. Spinal cord injury (SCI) results in a complex cascade of secondary damage responses that can exacerbate the initial injury or facilitate recovery. While inflammatory and fibrotic responses are known to be key regulators in promoting or repressing SCI repair, our understanding of their exact role in spinal regeneration is still evolving. While a mammalian model of enhanced regeneration would be invaluable for SCI studies, none currently exist. Translating therapies from non‐mammalian models that demonstrate spinal cord regeneration to mammals is complicated by a host of interspecific physiological differences. African spiny mice (genus Acomys) are a unique group of rodents that can regenerate full‐thickness skin, musculoskeletal tissue in the ear pinna, and recover from severe kidney injury. Multi‐organ tissue regeneration occurs coincident with inflammatory and scarring responses that are distinct from those of the non‐regenerating laboratory mouse (genus Mus). However, there are no published studies of Acomys regenerative capacity in the spinal cord. The objective of this study was to evaluate the potential of Acomys as a mammalian model of enhanced repair/recovery following spinal cord injury. Through histological analysis of uninjured tissue, we found that Acomys and Mus have similar gross neuroanatomical spinal structures. After SCI, motor and sensory functional tests revealed distinct functional recovery profiles between Acomys and Mus. Ongoing cellular studies of injured spinal tissue are investigating the macrophage and extracellular matrix profiles, which we predict to differ based on inflammatory and scarring responses to peripheral injuries. These preliminary data suggest that while Acomys and Mus have similar baseline spinal anatomy, the physiological response to injury is distinct and may provide insight to critical features leading mammalian SCI recovery and regeneration.

Support or Funding Information

5T32 NS077889

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Transcriptional and epigenetic control of cranial bone lineage development
Authors: Atit Radhika P
Published: June 2021

During development, proper spatiotemporal patterning and specification of tissues requires precisely orchestrated changes in gene expression, which are regulated by transcription factors and epigenetic modification in response to instructive cues from cell signaling pathways. Development of the skull bones requires the coordination of two stem progenitor populations, the cranial neural crest cells (CNCC) and head paraxial mesoderm (PM), to ensure cell fate selection and morphogenesis. We previously demonstrated that Wnt/β‐catenin signaling acts as a molecular switch in the cranial mesenchyme by simultaneously specifying cranial bone and dermal lineages and repressing cartilage cell fate. We identified Wnt signaling and TWIST1 function in a feed‐forward loop to sustain Wnt signaling and promote the differentiation of calvarial bone progenitors. In order to understand the function of epigenetic mechanisms calvarial bone development at different developmental stages, we conditionally deleted Ezh2 which is part of the Polycomb Repressive Complex 2 in a stage‐specific manner in vivo. We found that Ezh2 is required early and transiently to promote bone progenitor commitment. Inhibition of retinoic acid (RA) signaling in Ezh2 mutants in vivo rescues calvarial bone development, and RA signaling activation in the conditional Ezh2 background leads to synergistic activation of anti‐osteogenic factors, such as Hand2 and HoxC8. Our results suggest that RA signaling and Ezh2 can function in parallel in an incoherent type1 feed forward loop to balance the suppression of anti‐osteogenic factors to permit later differentiation events in the calvarial bone lineage program. Our data provide new insights into the dynamic gene regulation during the specification of calvarial bones and commitment to intramembranous bone formation.

Support or Funding Information

NIH‐NIDCR DE‐01870

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Decreased Number of Brainstem Serotonin (5‐HT) Neurons During Chronic Hypercapnia in Goats
Authors: Buchholz Kirstyn , Burgraff Nicholas , LeClaire John , Neumueller Suzanne , Pan Lawrence , Hodges Matthew , Forster Hubert
Published: June 2021

Thirty days after carotid body denervation (CBD) in goats, the number of neurons expressing the rate limiting enzyme for serotonin (5‐HT) synthesis (tryptophan hydroxylase, TPH), in the medullary raphe nuclei (MRN) and the ventrolateral medulla (VLM), was 50% of that in control goats (J. Appl. Physiol. 115, 1088–1098, 2013). This difference could be due to loss of carotid afferents per se, or it could be secondary to the CBD induced chronic hypercapnia. The objective of the present study was to assess the effect of hypercapnia per se on TPH expressing neurons in the MRN and VLM. To achieve the objective, we constructed environmental chambers to chronically house and study the effects of chronic hypercapnia in adult goats. Following a room air control period, the goats were exposed to either room air or an elevated inspired CO2 (InCO2) of 6% for 30‐days. After 30 days of hypercapnia, the brainstems were harvested and immunohistochemistry and western blots were used to determine whether chronic hypercapnia altered the number of TPH expressing neurons in the MRN and VLM. We found that there was a nearly 50% decrease (P<0.01) in the number of neurons expressing TPH within both the MRN and VLM. Additionally, there was a decline in the number of total neurons within these nuclei, suggesting that the loss of TPH expressing neurons may be from neuronal death. We conclude that chronic hypercapnia per se has a major impact on the 5‐HT neuromodulatory system which is important in the control of breathing.

Support or Funding Information

The Department of Veteran Affairs

NIH Grant 007852

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
S‐Nitrosoglutathione Reductase Inhibition Attenuates Airway Hyperreactivity in a Neonatal Hyperoxia‐Exposed Mouse Model
Authors: Sopi Ramadan B , MacFarlane Peter M , Gaston Benjamin , Martin Richard J , Raffay Thomas M
Published: June 2021

Premature infants exposed to supplemental oxygen are at risk for developing wheezing disorders and airway hyperreactivity (AHR). We have previously shown that the endogenous smooth muscle relaxant molecule, S‐nitrosoglutathione (GSNO), is degraded in neonatal hyperoxia by upregulated GSNO reductase (GSNOR) in the murine lung (Raffay, et al. Molecular Pharmacology 2016; 90(4):418–26). We hypothesize that inhibition or deletion of GSNOR will attenuate hyperoxia‐induced AHR in this neonatal mouse model. Newborn C57BL/6 wild‐type (background) or GSNOR−/− (knockout) mice were randomized on the first day of life and assigned to room air (21% O2) or hyperoxic (60% O2) groups for three weeks. At day P21, AHR was assessed in vitro using precision‐cut living lung slice preparations in response to increasing doses of bath‐applied methacholine (MCh, 0.25–64 μM). Wild‐type lung slices were pre‐incubated overnight with or without a GSNOR inhibitor (100 μM N6022). AHR is reported as percent change in airway lumen area from baseline (±SEM). 2–3 airways were imaged and averaged per animal per condition. Neonatal hyperoxia significantly increased (p<0.001) airway contractile responses to MCh in wild‐type mice with a mean maximal effect (Emax) of 70.4 ± 2.1% compared to the room air control Emax of 44.5 ± 9.1%. GSNOR inhibition significantly reduced airway contractile responses in wild‐type hyperoxic slices to 34.1 ± 4.2% (p<0.001). GSNOR−/− mice exposed to hyperoxia did not display increased airway contractile responses (Emax= 50.9 ± 5.5%). These studies show that neonatal hyperoxia‐exposed mice display in vitro AHR to methacholine and that inhibition or deletion of GSNOR attenuates hyperoxia‐induced AHR. We speculate that increased lung GSNOR expression is critical for neonatal hyperoxic bronchoconstriction. GSNO‐based therapies may serve as novel treatments for premature patients with AHR.

Support or Funding Information

Supported by NIH 5K08HL133459‐02 and ATS Foundation Unrestricted Research Grant

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The effect of voluntary movement with non‐dominant finger on the delay time of involuntary movement in a patient of mirror movement disorder
Authors: Ito Kimiko , Abe Chikara , Taketani Takeshi
Published: June 2021

Mirror movement disorder is a condition in which intentional movements of one side of the body are mirrored by involuntary movements of the other side. This symptom is mainly observed in the distal upper limbs. Mirror movement disorder is present in patients with a variety of movement disorders, such as dystonia, Parkinson's disease, and essential tremor as well as in congenital nervous system disorders. Mirror movement disorder is also observed in healthy subjects even in several members of the same family with no other neurological signs (Congenital mirror movement disorder). Although it is known that mutations in the DCC or RAD51 gene is involved in the congenital mirror movement disorder, it is still far from the understanding of the mechanism in congenital mirror movement disorder since its prevalence is thought to be less than 1 in 1 million. In this study, we found the healthy child and her father who had mirror movement. We report the quantitative analysis of the mirror movement using videotape recording. We obtained informed consent for the videotape recording and the experimental procedures from all subjects. In the subject of the child, we recorded the movement of both index fingers during pressing the button of the picture book by right index finger. The movement of the left index finger was observed 33 ms after pressing, and the maximum speed of the movement was comparable. In the subject of her father, we recorded the movement of both fingers during we asked him to move right or left one finger. The delay time between right (dominant) and left (non‐dominant) fingers was 24 ± 8 ms when we asked him to move the dominant finger. However, this value was significantly increased when the non‐dominant fingers were asked to move (133 ± 47 ms). In conclusion, child and her father had same symptoms; the involuntary movement was observed after voluntary movement with delay time. Increased delay time between voluntary and involuntary movement during the non‐dominant fingers were asked to move might be due to use‐dependent plasticity. This should be studied in the future study with anatomical/physiological examination of the brain and comprehensive inspection of genes.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The effect of smartphone light on the physiology signal and cognitive function in circadian environment
Authors: Lee Minkyung , Hong Yonggeun
Published: June 2021

Many people are constantly exposed to artificial light caused by digital devices such as computer, smartphone, and TV. Prolonged exposure to artificial light disturbs our circadian rhythm, cognitive function and autonomic nervous system (ANS). Therefore, this study aimed to analyze the alterations in physiological signals and cognitive functions following exposure to smartphone light in order to confirm the effects of artificial light on the human body. Normal adults aged from 21 to 28 were engaged in this study. The experiments were conducted in day (10:00~14:00) and night (8:00~12:00) conditions. Experimental subjects were divided into three groups according to smartphone screen brightness; 50%, 100%, and blue light filter (BLF), then used smartphone for 10 min/set (rest time: 5 min) and repeated the task three times. The ANS changes were confirmed using pulse pressure measurement equipment. Short‐term memory (STM), long‐term memory (LTM), and recognition tests were conducted via language memory test (LMT) and visual memory test (VMT). After using smartphone at daytime condition, 50% group shoed significantly increased ANS activity. Also, LTM and recognition were significantly increased in the 50% and BLP group. In night condition, however, BLF group showed increased LTM and recognition. It has been demonstrated by this study that smartphone light may influence ANS, memory, and cognitive functions. Accordingly, blue light filter is recommended when using smartphone to reduce such harmful alterations.

Support or Funding Information

Funds: NRF‐2017R1A2A2A01067169, KGM4611821, 2016 Creative Research Program of Inje University, Republic of Korea

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The &[Alpha]2δ‐1–NMDA Receptor Coupling is Essential for Corticostriatal Long‐Term Potentiation and is Involved in Learning and Memory
Authors: ZHOU JINGJING , Li De‐Pei , Chen Shao‐Rui , Luo Yi , Pan Hui‐Lin
Published: June 2021

The striatum receives extensive cortical input and plays a prominent role in motor learning and habit formation. Glutamate N‐methyl‐Daspartate (NMDA) receptor (NMDAR)‐mediated long‐term potentiation (LTP) is a major synaptic plasticity involved in learning and memory. However, the molecular mechanism underlying NMDAR plasticity in corticostriatal LTP is unclear. Here, we show that theta‐burst stimulation (TBS) consistently induced corticostriatal LTP and increased the coincident presynaptic and postsynaptic NMDAR activity of medium spiny neurons. We also found that α2δ‐1 (previously known as a subunit of voltage‐gated calcium channels; encoded by the Cacna2d1 gene) physically interacted with NMDARs in the striatum of mice and humans, indicating that this crosstalk is conserved across species. Strikingly, inhibiting α2δ‐1 trafficking with gabapentin or disrupting the α2δ‐1–NMDAR interaction with an α2δ‐1 C‐terminus–interfering peptide abolished TBS‐induced LTP. In Cacna2d1‐knockout mice, TBS failed to induce corticostriatal LTP and the associated increases in presynaptic and postsynaptic NMDAR activities. Moreover, systemic gabapentin treatment, microinjection of α2δ‐1 C‐terminus–interfering peptide into the dorsomedial striatum, or Cacna2d1 ablation impaired the alternation T‐maze task and rotarod performance in mice. Our findings indicate that the interaction between α2δ‐1 and NMDARs is of high physiological relevance and that a TBS‐induced switch from α2δ‐1–free to α2δ‐1–bound NMDARs is critically involved in corticostriatal LTP and LTP‐associated learning and memory. Gabapentinoids may adversely affect cognitive function by targeting α2δ‐1–NMDAR complexes.

Support or Funding Information

Human brain tissues were obtained from the Harvard Brain Tissue Resources Center, a NeuroBioBank Repository funded by the National Institutes of Health. This work was supported by the National Institutes of Health (GM120844 and NS101880 to H.‐L.P.) and by the N.G. and Helen T. Hawkins Endowment.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Exercise‐augmentation of fear extinction depends on mTOR signaling
Authors: Smith Abigail Marilyn , Moya Nicolette , Tanner Margaret , Balolia Aleezah , Davis Jazmyne , Loetz Esteban , Jaime Jennifer , Greenwood Benjamin
Published: June 2021

Exercise has beneficial effects on cognition and mental health, such as enhancing the extinction of a traumatic memory. Rats allowed to run in a wheel for a single, two‐hour session immediately following fear extinction training show enhanced fear extinction memory. The mechanisms by which exercise augments fear extinction are unknown. The mammalian target of rapamycin (mTOR) is a translation regulator involved in synaptic plasticity, and is a target of cellular signals sensitive to exercise. Chronic exercise increases mTOR signaling in brain regions involved in extinction learning, but whether a single bout of exercise capable of enhancing fear extinction increases mTOR is also unknown. The goal of this study was to determine if a single session of wheel running increases mTOR signaling and, if so, whether mTOR signaling contributes to the exercise‐augmentation of fear extinction. Adult, male Long Evans rats exposed to auditory fear conditioning received intracerebral‐ventricular injections of the mTOR inhibitor rapamycin prior to fear extinction training. Immediately after fear extinction training, rats were placed in locked or mobile running wheel for two hours. Post‐extinction exercise enhanced fear extinction memory retrieval the following day, and this effect was blocked by rapamycin.

Moreover, an acute bout of exercise increased mTOR signaling in several regions involved in memory and fear extinction. The increase in mTOR signaling produced by exercise was also blocked by rapamycin. These data suggest that acute exercise enhances fear extinction through a mechanism involving mTOR signaling.

Support or Funding Information

Supported by the Undergraduate Research Opportunity Program, 2 T34 GM096958‐06, and NIH MH114992

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Role of the Dorsal Striatum in Fear Extinction and Relapse
Authors: Balolia Aleezah , Tanner Margaret K , Moya Nicolette A , Wiseman John R , Loetz Esteban C , Davis Jazmyne KP , Jaime Jennifer , Oleson Erik B , Greenwood Benjamin
Published: June 2021

The poor long‐term success of fear extinction‐based exposure therapy for post‐traumatic stress disorder (PTSD) is often caused by the relapse of previously extinguished fear. We have previously observed that activation of substantia nigra (SN) dopamine (DA) neurons during fear extinction enhances extinction memory and reduces renewal. Although the specific targets mediating the effects of SN DA on extinction are unknown, their identification could pave the way for the development of novel strategies to reduce fear relapse in PTSD patients. A primary target of SN DA is the dorsal striatum, which consists of two regions: The dorsomedial striatum (DMS), responsible for goal directed learning, and the dorsolateral striatum (DLS), concerning more inflexible, habitual behaviors. The goal of these experiments was to begin to investigate the roles of the DMS and DLS in fear extinction and relapse in adult, male Long Evans rats. Inactivation of the DLS during auditory fear extinction with a Muscimol/Baclofen cocktail (0.03/0.3 nmol/uL) enhanced fear extinction memory but had no effect on fear renewal, while inactivation of the DMS prevented renewal, but had no effect on extinction memory in the extinction context. To investigate the involvement of DA, D1 receptor signaling was blocked in either the DMS or DLS during fear extinction. D1 blockade in the DMS impaired extinction retrieval in the extinction context, but the extinction memory remained susceptible to renewal. D1 blockade in the DLS had no effect on extinction memory or renewal. Despite this, optogenetic stimulation of SN terminals in the DLS during fear extinction reduced fear renewal without impacting extinction memory in the extinction context. These results suggest that the DMS and DLS play different roles in fear extinction and relapse. The DMS supports context‐specific fear extinction through a mechanism involving D1 receptor signaling. Although the contribution of the DLS to normal fear extinction is minimal, fear extinction memory can be rendered resistant to renewal by manipulations that increase the role of the DLS in extinction (DMS inactivation, optogenetic stimulation). Manipulations that increase the involvement of the DLS in fear extinction, such as exercise, could therefore represent effective augmentation strategies for fear extinction in order to reduce relapse.

Support or Funding Information

NIH grant 068283 NIH grant 2 T34 GM096958‐06

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cardiovascular and autonomic modulation in trained rats: effects of iNOS inhibition and oxidative balance in the rostroventrolateral medulla
Authors: Martins‐Pinge Marli Cardoso , de Ataides Raquel Hiviny , Michelini Lisete
Published: June 2021

We proposed to investigate the participation of the inducible nitric oxide synthase (iNOS) on glutamatergic neurotransmission and the oxidative profile in the rostral ventrolateral medulla (RVLM) in trained rats. Wistar rats were submitted to physical training (T) protocol or sedentary (S) for 4 weeks. After the last swimming session, the animals were submitted to guide cannulae implantation directed to RVLM. After 3 days of surgical recovery, femoral artery and vein catheterization were performed for direct recording of mean arterial pressure (MAP) and heart rate (HR). The acquired cardiovascular data underwent spectral analysis (Cardio Series®).

An inhibitor of iNOS (aminoguanidine, 250pmol/100nl) was unilaterally microinjected into the RVLM. Other animals received microinjection of glutamate (5nmol/100nl) in RVLM, before and after of the aminoguanidine. Bilateral punchs of RVLM were collected for analysis of iNOS gene expression (real‐time PCR); quantification of reduced glutathione and lipid peroxidation (spectrophotometer); iron‐reducing antioxidant (FRAP) and ABTS radical scavenger (Multiskan GO ThermoScientific®). T Animals presented a reduction in the gene expression of iNOS in RVLM associated to rest bradycardia (S: 371±8 vs. T: 312±8 b/min, r2= 0.58) and higher antioxidant capacity (FRAP; S: 5±1 vs. T: 9±1.3 nmol Trolox Eq/mg protein). Swimming improved baroreflex sensitivity (S: 1.04±0.06 vs. T: 2.4±0.28 ms2/mmHg2) and lower sympathovagal ratio (LF/HF, S: 0.6±0.09 vs. T: 0.2±0.02). In T rats, the inhibition of iNOS in RVLM caused a lower pressor response (ΔMAP: S: 32±3 vs. T: 20±2 mm/Hg) and tachycardia (ΔHR: S: 55±4 vs. T: 43±1 b/min), abolishing previous differences in HR variability between groups. The microinjection of glutamate in RVLM of T group caused a lower pressor response (ΔMAP: S: 60±6 vs. T: 41±2 mmHg) and tachycardia (ΔHR: S: 90±4 vs. T: 58±3 b/min) and after iNOS inhibition in RVLM, we observed a greater glutamatergic response in T animals (ΔMAP: 69±3 mmHg). In conclusion, the cardiovascular benefits of physical training can be associated with decreased modulation by NO in RVLM via iNOS and also reduction of oxidative stress in this vasomotor center.

Support or Funding Information

CAPES (felowship)

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Ionotropic and Metabotropic Glutamate Receptors Contribute to Cardiorespiratory Responses to Inhibition of Astrocytic Excitatory Amino Acid Transporters
Authors: Martinez Diana , Friskey Sarah , Kline David , Hasser Eileen
Published: June 2021

The nucleus tractus solitarii (nTS) is the initial site of termination of cardiorespiratory afferents, which transmit signals through release of glutamate (Glu). Afferent information is integrated extensively in the nTS, thus shaping its output and cardiorespiratory responses. We have shown that inhibition of astrocytic excitatory amino acid transporter 2 (EAAT2) in the nTS increased ambient [Glu] and altered basal and reflex cardiorespiratory function. These effects were partially blocked by ionotropic glutamate receptor (iGluR) antagonism. We hypothesized that the responses remaining after iGluR blockade were due to activation of metabotropic (m)GluRs. To test this, Inactin‐anesthetized rats were instrumented to record mean arterial pressure (MAP), heart rate (HR), splanchnic sympathetic and phrenic nerve activity (SSNA; PhNA), and for microinjections into the nTS. The general EAAT inhibitor TFB‐TBOA (10 μM, 90 nl) was microinjected unilaterally into the nTS. GluR antagonists or vehicle (aCSF) were then microinjected, followed by two additional injections of TBOA. Unilateral nTS microinjection of TBOA decreased MAP, HR, PhNA and SSNA, consistent with effects of increased [Glu] in the nTS. Following aCSF, additional injections of TBOA produced augmented as well as prolonged cardiorespiratory responses. Prior blockade of iGluRs with a cocktail (90 nl) of NBQX (2 mM) and AP5 (10 mM) reduced the response to EAAT inhibition. However, it did not prevent the augmented effects of repetitive TBOA, indicating a role for other receptors. The effects of combined blockade of iGluRs and Group II/III mGluRs (MSOP, 100 mM + eGlu, 10 mM; 90 nl total) were similar to those of iGluR antagonism alone. In contrast, combined blockade of iGluRs and Group I mGluRs (LY367385, 10 mM; 90 nl total) blunted the cardiorespiratory effects of nTS EAAT inhibition, and markedly attenuated enhanced responses to subsequent injection of TBOA. These data are consistent with the concept that nTS inhibition of astrocytic EAATs increases [Glu], producing cardiorespiratory responses similar to excitation of nTS neurons involved in baroreflex function. These effects of EAAT inhibition are mediated primarily by iGluRs and Group I mGluRs. It is possible that Group II/III mGluRs also contribute via other mechanisms.

Support or Funding Information

Supported by HL132836 and HL128454

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cardiovascular Deconditioning Induces Changes in the Excitatory Neurotransmission and Active Properties of Nucleus Tractus Solitarii Neurons
Authors: Silveira Ludmila Lima , Hasser Eileen M , Kline David D
Published: June 2021

Hindlimb‐unloading (HU) in rats induces cardiovascular deconditioning analogous to that observed in individuals exposed to microgravity or bed rest. Among other physiological changes, HU rats exhibit autonomic imbalance, increased baseline heart rate and altered baroreflex and chemoreflex. Considering that the nucleus tractus solitariis (nTS) is an important central region for autonomic control and integration of cardiovascular reflex function, in this study we aimed to investigate the effects of HU on glutamatergic synaptic transmission and intrinsic properties of nTS neurons. For this purpose, stainless steel wire rings were positioned in the tail of male Sprague‐Dawley rats (3 weeks) and after one week of recovery the rings was connected to a suspension apparatus. HU rats were suspended at an angle of 30–35° for two weeks with free access to food and water, while control animals were maintained under normal postural conditions. After this period, coronal brainstem slices were obtained and the whole‐cell patch clamp technique was performed to evaluate the electrophysiological properties of nTS neurons. The effectiveness of the HU protocol was confirmed by significant hindlimb muscle atrophy. Adrenal weight was comparable between HU and control rats. Resting membrane potential of nTS neurons from HU rats was comparable to neurons from controls. However, HU reduced the percentage of neurons that exhibited spontaneous firing activity (Control: 46% vs HU: 11%). In addition, HU induced a significant increase in the action potential rheobase and A‐type potassium current of nTS neurons, which may contribute to altered basal firing rate. Furthermore, the frequency, but not the amplitude of spontaneous excitatory postsynaptic currents (sEPSC) was significantly higher in the neurons of HU rats in comparison to the control. Taken together the data indicated that HU increases glutamatergic neurotransmission and reduces the excitability of NTS neurons. Therefore, the results suggest that changes in neuronal activity and synaptic transmission in the nTS may contribute to the cardiovascular reflex alterations observed in HU rats.

Support or Funding Information

Support: HL132836

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Functional Topography in the Rat Rostral Ventrolateral Medulla (RVLM): Distribution of C1 Neurons that Respond to Cardiovascular versus Metabolic Stimuli
Authors: Llewellyn‐Smith Ida J , Senthilkumaran Manjula , Spradley Frank , Etelvino Gisele M , Bobrovskaya Larisa , Carrive Pascal , Mueller Patrick J , Verberne Anthony J M
Published: June 2021

Neurons controlling cardiovascular responses and glucose counter regulation are co‐located within the RVLM, with activated neurons lying almost exclusively caudal to the caudal pole of the facial nucleus (FN). However, it is unclear whether the same neurons are involved in triggering both cardiovascular and metabolic responses. We compared the distributions of RVLM C1 neurons activated by cardiovascular or metabolic stimuli using Fos to identify activated neurons. To conscious male or female rats, we administered insulin (10 U/kg ip) or 2‐deoxyglucose (2DG; 400 mg/kg sc) to induce hypoglycaemia or nitroprusside (NP; 1 mg/ml iv), hydralazine (HDZ; 10 mg/kg iv) or diazoxide (DZX; 50 mg/kg iv) to cause hypotension. Rats were transcardially perfused with formaldehyde 90 or 120 minutes later. Coronal 30‐micrometer thick sections of medulla (1:4 series) from the spinomedullary junction to mid‐FN were immunoperoxidase‐stained to show Fos‐immunoreactivity plus phenylethanolamine N‐methyl transferase (PNMT)‐immunoreactivity to identify C1 neurons. The 6 sections containing the 600 micrometers caudal to the caudal pole of FN (sections FN0 to FN‐5) were each divided into 3 equal segments (medial, middle, lateral) and the total numbers of PNMT neurons with Fos nuclei (Fos+PNMT neurons) were counted. The numbers of Fos+PNMT neurons were greater in the medial and middle thirds than in the lateral third of the C1 cell column in insulin‐ and 2DG‐treated rats. In NP‐, DZX‐or HDZ‐treated rats, the numbers of Fos+PNMT neurons were greater in the middle and lateral two thirds of the C1 cell column. Two‐way ANOVA showed a very strong interaction between stimulus and laterality (p<0.0001), both for number of Fos+PNMT neurons and for percentage of PNMT neurons with Fos nuclei. These results reveal that the extent of Fos expression in PNMT neurons in the medial versus lateral zones depends on the type of stimulus. Post‐hoc analysis confirmed that, in the medial zone, the metabolic stimuli activated more PNMT neurons than cardiovascular stimuli, while it was the opposite in the lateral zone (p<0.0001 in both cases). These results show that hypoglycaemia‐responsive RVLM C1 neurons are concentrated in the medial and middle thirds of the C1 cell column whereas hypotension‐responsive RVLM C1 neurons are concentrated in the middle and lateral two thirds of the column. Hence, within the rat RVLM, C1 neurons are distributed topographically according to their function.

Support or Funding Information

NHMRC 1025031; NIH HL096787 & HL130577

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Voluntary Exercise Prevents Hypertensive Response Sensitization (HTRS)
Authors: Xue Baojian , Beltz Terry G , Guo Fang , Johnson Alan Kim
Published: June 2021

Exercise training has profound effects on the renin‐angiotensin system (RAS), inflammatory mediators and ROS production, all of which influence autonomic nervous system activity and regulates cardiovascular function in both physiological and pathophysiological states. Our previous studies using an Induction‐Delay‐Expression (IND‐DEL‐EXP) paradigm to study HTRS demonstrated that various challenges (stressors) including a subpressor dose of angiotensin (ANG) II given during IND, resulted in HTRS to a subsequent treatment with slow‐pressor dose of ANG II during EXP. The present study tested whether voluntary exercise would protect against subpressor ANG II‐induced HTRS in rats. Adult male rats were given access to either “blocked” (sedentary rats) or functional running (exercised rats) wheels for 10 weeks, and the IND‐DEL‐EXP paradigm was applied for the rats during the last 4 weeks. A subpressor dose of ANG II (10 ng/kg/min) given during IND produced an enhanced hypertensive response to a pressor dose of ANG II (120 ng/kg/min) given during EXP in sedentary rats in comparison to sedentary animals that received saline (vehicle control) during IND. Voluntary exercise did not attenuate the pressor dose of ANG II‐induced hypertension, but prevented the induction of HTRS seen in sedentary animals. Moreover, the subpressor dose of ANG II given during IND induced upregulation of mRNA expression of several RAS pro‐hypertensive components and proinflammatory cytokines in the lamina terminalis (LT), which was attenuated by exercise. Also, RAS antihypertensive components, such as angiotensin type 2 receptor (AT2‐R) and Mas‐R, were upregulated by subpressor dose of ANG II in exercised rats. These results indicate that exercise training plays a beneficial role in preventing HTRS and that this is associated with reduced expression of increased pro‐hypertensive components of the RAS and of inflammatory mediators and by enhanced expression of RAS antihypertensive components in the CNS.

Support or Funding Information

This work is supported by the NIH grants HL‐14388 (AKJ), HL‐98207 (AKJ & BX), HL‐139575 (AKJ & BX).

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Evaluation of Respiratory and Cardiovascular Parameters by Ultrasound Echography Following C2 Spinal Cord Hemisection in Rat
Authors: Michel‐Flutot Pauline , Fayssoil Abdallah , Bonay Marcel , Mansart Arnaud , Vinit Stéphane
Published: June 2021

High cervical spinal cord injuries induce several permanent deficits of vital functions, often leading to the death of the patient. The injury immediately disrupts the bulbospinal pathways innervating phrenic motoneurons that connect to the diaphragm and also causes damages to the sympathetic innervation of the vascular system. The subsequent functional deficits are respiratory failure and cardiovascular dysfunction. In this study, we use a preclinical model of surgical cervical C2 partial section in the rat that mimic these respiratory and cardiovascular impairments. The physiopathology of the injury is assessed by the adaptation of a non‐invasive medical ultrasound echography device (Logic 9, GE, France) to our model.

Seven days post‐injury, we observed a live passive displacement of the diaphragm by ultrasound on the injured side in anesthetized animals, corresponding to an absence of hemidiaphragm contraction (−0,37 ± 0,17 mm) compared to contralateral side (3,27 ± 0,44 mm; p<0,01) and to control group (3,79 ± 0,27 mm; p<0,01). These results have been confirmed by in vivo diaphragmatic electromyography, with low electromyographic activity recorded on the ipsilateral side (0,06 ± 0,03 μV.s.s) compared to the contralateral side (0,53 ± 0,08 μV.s.s; p<0,01) and to control group (0,33 ± 0,08 μV.s.s; p = 0,013). We also observed a reduction of the thickness of the rectus abdominis muscle (accessory expiratory muscle) on both sides (injured and non‐injured) at 7 days post‐injury (non‐injured side = 1,78 ± 0,10 mm; injured side = 1,80 ± 0,10 mm) compared to control (2,14 ± 0,08 mm; p = 0,009 and p = 0,013 respectively), suggesting a role for this muscle in active exhalation following the injury.

The doppler echocardiography for the cardiovascular evaluation showed a statistical reduction of the left ventricular ejection fraction (LVEF = 59 ± 3%) compared to control (LVEF = 70 ± 2%; p = 0,01), which corresponds to a systolic dysfunction. However, no diastolic dysfunction has been observed. The mean arterial pressure is getting close to non‐injured levels at 7 days post‐injury (68 ± 7 mmHg) compared to control group (84 ± 10 mmHg). These results suggest that the reduction of the sympathetic innervation caused by the spinal cord injury conduct to a cardiovascular dysfunction partly corrected at 7 days post‐injury.

Altogether, we demonstrate that medical ultrasound machine could be a reliable non‐invasive method to evaluate chronic respiratory and cardiovascular dysfunction following high cervical spinal cord injury and for studying chronically the evolution of the eventual spontaneous restoration that can occur in this model.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Blockade of Neuropeptide Y Y1 Receptors in the Dorsomedial Hypothalamus Increases Sympathetic Nerve Activity via Projections to the Hypothalamic Paraventricular Nucleus
Authors: Bonillas Alyssa , Shi Zhigang , Padilla Stephanie L. , Brooks Virginia L.
Published: June 2021

Arcuate Neuropeptide Y (NPY) neurons tonically suppress basal sympathetic nerve activity (SNA) via binding of NPY to NPY Y1 receptors (NPY1R) in the hypothalamic paraventricular nucleus (PVN) and the dorsomedial hypothalamus (DMH). Projection targets of PVN pre‐sympathetic neurons that are inhibited by NPY include the rostral ventrolateral medulla. However, the downstream targets of DMH NPY‐receptive neurons are unknown. Because DMH neurons send a major projection to the PVN, we hypothesized that the PVN is one target. To test this hypothesis, male Npy1r‐cre mice (n=2) received unilateral DMH injections of an adeno‐associated virus, which allows for the cre‐dependent expression of a fluorescent protein (mCherry) in the cell bodies and axon fibers of NPY1R‐containing neurons. After about two weeks, the animals were sacrificed, and their brains were immunohistochemically processed to enhance the mCherry signal. In support of our hypothesis, we identified an abundance of mCherry‐labeled fibers in the PVN. A second prominent projection target was the nucleus raphe pallidus, an important medullary region involved in the regulation of brown adipose tissue thermogenesis. Next, to test the physiological significance of the DMH projection to the PVN, in α‐chloralose anesthetized WT male mice (n=5), we first bilaterally injected the selective NPY1R antagonist, BIBO3304 (30 nl of 10 mM/L), into the DMH, which increased (all P<0.05) splanchnic SNA (SSNA) by 40±12% control, mean arterial pressure (MAP) from 82±5 to 97±6 mmHg, and heart rate (HR) from 449±35 to 554±29 bpm. After 15 min, the inhibitory GABAA agonist, muscimol (30 nL of 1 mM/L), was injected bilaterally into the PVN and reversed the effects of DMH BIBO3304: SSNA decreased to 112±7 % control, MAP to 83±7 mmHg, and HR to 471±25 bpm. In conclusion, NPY tonically inhibits DMH pre‐sympathetic neurons that express NPY1R and project to the PVN.

Support or Funding Information

HL128181; APS/Hearst UGSRF

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Intracellular Chloride Regulation of Supraoptic Vasopressin Neurons during Salt Loading
Authors: Balapattabi Kirthikaa , Farmer George E , Little Joel T , Bachelor Martha E , Cunningham J. Thomas
Published: June 2021

Salt loading (SL) increases intracellular chloride concentration [Cl]i, impairing GABAA inhibition of arginine vasopressin (AVP) neurons in the supraoptic nucleus (SON) of hypothalamus. But the regulatory mechanisms leading to increased [Cl]i is not completely understood. Based on previous studies, we hypothesize that SL activates tyrosine receptor kinase B (TrkB) and downregulates K+/Cl− co‐transporter 2 (KCC2) membrane expression. Downregulation of KCC2 decreases the efflux of chloride ion causing increase in [Cl]i in SON AVP neurons. In this study, we have combined virally mediated ClopHensorN, a relatively new ratiometric chloride imaging technique with capillary based Simple Western technology to record changes in [Cl]i and specifically detect KCC2 protein expression in individual SON AVP neurons.

Adult male Sprague Dawley rats were bilaterally injected in the SON with rAAV2‐0VP1‐ClopHensorN. The ClopHensorN (Addgene Plasmid #50758 from Colin Akerman) was packaged in an AAV2 vector with a AVP specific promotor (Addgene Plasmid #40868 from Harold Gainer). After 2 weeks, the rats were given either water or 2% NaCl to drink for 7 days. At the end of the protocol, the rats were anesthetized with inactin and their SONs were dissociated. The cells were plated on coverslips and placed in a perfusion bath on an inverted microscope for ratiometric live cell imaging. ClopHensorN positive neurons were tested for decrease or increase in [Cl]i to focal application of GABAA agonist muscimol (100uM). After imaging, individual neurons were collected by aspirating into a patch pipette to verify KCC2 and ß‐Actin protein expression. The standard matrix (12–230kDa) in Protein Simple Wes was used to identify and quantitate very low concentration of protein from single neuron. Data were analyzed by Chi‐squared test and one‐way ANOVA with Bonferroni comparisons.

Muscimol application to SL SONs either significantly increased chloride efflux (p<0.05;13/20) or did not change chloride flux (7/20). TrkB antagonist (AnA,50uM) significantly blocked the chloride effluxes. SONs from euhydrated rats showed muscimol induced chloride influx (p<0.05;11/16). KCC2 antagonist (VU 0240551,10uM) significantly blocked the chloride influxes in euhydrated rats. SON AVP neurons that responded to pharmacological inhibitors during chloride imaging were viable and expressed KCC2 co‐transporter and ß‐Actin. Neurons that did not respond during chloride imaging did not had KCC2 and ß‐Actin protein expression. Salt loading increases [Cl]i in SON AVP neurons through TrKB‐KCC2 dependent mechanism.

Support or Funding Information

Supported by R01 HL119458 and 18PRE34060035

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.