bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estrogen inhibit salt‐overload induced hypernatremia in ovariectomized female rats (683.5)
Authors: Araujo Iracema , Mecawi André , Vilhena‐Franco Tatiane , Dos‐Santos Raoni , Elias Lucila , Antunes‐Rodrigues José , Reis Luís 
Published: June 2021

Since estrogen is controversially implicated on sodium balance, our aim in the present study was to evaluate the estrogen modulations on female rats under basal and salt‐overload conditions. Female Wistar rats were bilaterally ovariectomized (OVX) and randomly divided in two groups to receive estradiol benzoate (EB‐OVX, 10 µg/0.1 mL/animal, s.c.) or vehicle (OVX, 0.1 mL/animal, s.c.). The animals were placed in metabolic cages for adaptation; 7 days after the estradiol or vehicle treatement beggining, two experimental protocols were performed in OVX and EB‐OVX rats: i) basal water or water plus saline (0.075, 0.15 and 0.3 M NaCl) offering and, ii) salt‐overload (0.3 M NaCl offered as only fluids) during 3 or 15 days. OVX and EB‐OVX rats exhibited a decreased 0.3 M saline preference compared to hypotonic and isotonic solutions. Also, salt overloaded rats showed a progressive increase of hypertonic intake, as only fluid offered, with no changes induced by estrogen. However, estrogen induced a inhibition of hypernatremia on EB‐OVX rats induced by high salt ingestion when compared to OVX. Additionally, AVP and OT increasing in response to salt loading was not modulated by estrogen, meanwhile estrogen inhibited and attenuated the decrease on ANP and ANG II plasma concentrations, respectively. Taken together, our present findings suggest that estrogen participates on the control of natremia in salt‐overloaded rats.Grant Funding Source: Supported by FAPERJ and FAPESP
Antidepressant‐like effects after chronic treatment with zinc chloride (684.14)
Authors: Seara Fernando , Laureano‐Melo Roberto , Novais Renata , Araujo Iracema , Almeida Claudio , Conceicao Rodrigo , Reis Luis , Silva Alba , Cortes Wellington 
Published: June 2021

This study aimed to elucidate, for the first time, the effects of chronical oral treatment with zinc chloride on the depressant‐like behavior of Wistar rats and correlate them with the neuroendocrine profile promoted by our protocol. Two groups of male Wistar rats (200‐250 g) were treated with zinc chloride (15 mg/kg n=16) or isotonic saline (n=17) during 30 days. The rats were kept in a controlled room temperature with light/dark cycle and food ad libitum. After the treatment, both groups were submitted to a behavioral assessment in an open field (OF), elevated plus maze (EPM) and forced swim (FS) test for five minutes. Moreover, basal plasma corticosterone, triiodothyronine (T3), thyroxine (T4) were measured. Also, iodothyronine deiodinase type 2 (Dio2) activity in brown adipose tissue (BAT) and hippocampus were assessed. In view of our results, chronic treatment with orally zinc chloride does not alter the spontaneously locomotor activity as assessed by OF. However, zinc‐treated group showed anxiolytic effects as shown by less time of grooming (P<0,05), even though the episodes of grooming did not differ between groups. Corroborating the aforementioned anxiolytic effects on OF, zinc treatment reduced the time spent in closed arms (P<0,01) and the number of fecal pellets (P<0,05) on EPM. Yet, zinc‐treated group showed fewer immobilization time compared to control group on FS (P<0,05). Regarding to neuroendocrine profile, zinc‐treated group showed higher plasmatic T3 (P<0,01), however there were no differences on serum corticosterone and T4. Furthermore, there were no differences on Dio2 activity on BAT and hippocampus. We can conclude that chronically treatment with orally zinc chloride provides antidepressant‐like effects and discrete anxiolytic‐like effects during adulthood, presumably by raising plasma T3 level with no involvement of Dio2, taking into account that rodents with signs of depression‐like behavior often present hypothyroidism.Grant Funding Source: FAPERJ/CNPq
Postoperative cognitive dysfunction depends on the type of surgery (684.6)
Authors: Hovens Iris , Schoemaker Regien , van der Zee Eddy , van Leeuwen Barbara 
Published: June 2021

The risk of postoperative cognitive dysfunction (POCD) is higher after cardiac surgery compared to non‐cardiac surgery. The objective of this study was to compare POCD after cardiac and non‐cardiac surgery in rats as tool to study the underlying mechanisms.Male Wistar rats received abdominal surgery with ischemia‐reperfusion (i.r.) of the upper mesenteric artery (A‐S, n=12) or cardiac surgery with i.r. of the left coronary artery (MI‐S, n=12). Controls remained naive (C: n=12), received only anesthesia (A: n=12) or sham thorax surgery (T‐S, n=12). Weight loss accounted for severity of surgery. On postoperative day 10 to 14, cognition was assessed in the novel object and location test and Morris water maze (MWM).Location recognition was impaired in A‐S and MI‐S. Only A‐S displayed impaired spatial memory in the MWM, whereas only MI‐S displayed impaired object recognition and cognitive flexibility in the MWM. T‐S or A did not cause any cognitive impairment. All surgical procedures induced weight loss. MI‐S lost more weight than A‐S.Abdominal surgery only impaired spatial cognition, whereas cardiac surgery led to a more generalized cognitive dysfunction, indicating POCD depends on the type of surgery. Analysis of (neuro)inflammatory markers may reveal the basis of these findings and thus provide valuable insight in the mechanisms underlying POCD.
Convergent protein signaling in cerebral cavernous malformations (685.5)
Authors: Tsai Eric , Stockton Rebecca 
Published: June 2021

Cerebral Cavernous Malformations (CCMs) are vascular brain lesions affecting 0.5% of humans. Late stage lesions are clusters of grossly dilated capillaries lacking smooth muscle cell or pericyte support, and can cause hemorrhagic stroke. No treatment exists other than surgical removal of symptomatic lesions. CCMs occur sporadically through spontaneous mutations, or by familial autosomal dominant transmission of mutations in three genes : KRIT1, CCM2 or CCM3 (PDCD10). Our lab’s previous work showed that KRIT1 and CCM2 normally regulate endothelial permeability through regulation of RhoA and ROCK1/2. We now used proteomics and CHO cell co‐immunoprecipitations to identify a signalosome consisting of a unique brain microvascular endothelial cell‐specific splice variant of Rap1‐interacting junctional protein MAGI, “MAGI1C‐beta2”, that binds to KRIT1 and CCM2 through a PDZ domain to mediate translocation of two CCM proteins to endothelial junctions, and is required to maintain barrier function. We further identified a MAGI‐1 interacting protein , AMOT (angiomotin) as a convergence point for all three CCM protein signaling pathways, by showing that PDCD10 interacts directly with AMOT at junctional complex , while KRIT1 and CCM2 are localized there through MAGI1C‐beta2. The intact CCM1‐2‐3/MAGIC‐beta2/ AMOT complex suppresses RhoA activation, providing a mechanistic explanation for some aspects of CCM lesion development.Grant Funding Source: NIH
Angiotensin II stimulates reactive oxygen species production in PVN microglial cells via TLR4 receptor activation (686.1)
Authors: Biancardi Vinicia , Stern Javier 
Published: June 2021

Reactive oxygen species (ROS) has been highlighted as a mechanism by which Angiotensin II (AngII) exerts its deleterious effects in cardiovascular diseases. Yet, the precise cellular targets and mechanisms underlying AngII‐ROS production remain unknown. Since toll like receptor 4 (TLR4) in microglia cells can lead to ROS production, we hypothesize here a pathophysiological link between AngII, TLR4 and microglial cells in ROS production within the hypothalamic paraventricular nucleus (PVN). We found co‐immunostaining between microglial cells (IBA1), TLR4 and AT1 receptors within the PVN, providing anatomical evidence for such a crosstalk. Using dihydroethidium (DHE) to evaluate in situ ROS production, we found that AngII (1 μΜ), increased DHE within the PVN of rats (~65%, P<0.001) when compared to DHE in the presence of vehicle. AngII‐ROS production was decreased in the presence of the microglia inhibitor minocycline (100 μΜ; ~31%, P<0.05) suggesting microglia involvement in AngII‐ROS production. To determine the contribution of TLR4 to AT1‐ROS production, we used TLR4 sufficient and deficient mice (C3H/HeJ). We observed that AngII increased PVN DHE in TLR4 sufficient mice (~28%, P<0.05), an effect that was absent in TLR4 deficient mice. Taken together, these studies support a major contribution of microglial TLR4 to AngII‐mediated oxidative stress within the PVN.Grant Funding Source: Supported by RO1 HL 090948.
Insulin in the arcuate nucleus increases sympathetic nerve activity via extracellular signal‐regulated kinases (686.12)
Authors: Streiff Cole , Cassaglia Priscila , Shi Zhigang , Li Baoxin , Brooks Virginia 
Published: June 2021

Intracerebroventricular (ICV) insulin infusion increases SNA, which can be prevented by prior brain inhibition of ERK activation; however, the brain site of ERK activation is unknown. To test the hypothesis that ERK is involved within the site of action of insulin, the arcuate nucleus (ArcN), we first determined if bilateral ArcN nanoinjection of the ERK inhibitor PD98059 (60 nL of 0.5 mM/L) prevents the increases in lumbar SNA (LSNA) induced by ArcN insulin (60 pU in 30 nL) in α‐chloralose‐anesthetized male rats. ArcN insulin increased LSNA from 101±3 to 130±6 % control (P<0.05; n=5). PD98059 alone had no effects (108±9 to 112±8 % control), but subsequent ArcN insulin failed to increase LSNA (105±7 to 102±2 % control; n=4). In contrast, ArcN insulin still increased LSNA (106±4 to 147±24 % control; P<0.05) following ArcN blockade of PI3K (LY294002; 60 nL of 0.5 mM/L; n=5). Next, insulin (100 µU/min; n=3) or aCSF (0.6 µL/min; n=3) was infused ICV for 35 min, followed by dual ArcN immunohistochemistry of activated ERK and the insulin receptor (InsR). While there was no difference in the number of ArcN InsR immunoreactive (‐ir) neurons between insulin‐infused (223±17) and aCSF‐infused (263±21) rats, activated ERK‐ir was found only in the ArcN of insulin infused rats (137±13 vs. 7±2 neurons; P<0.05), with 34±6% of InsR‐ir neurons also expressing activated ERK‐ir. In conclusion, ArcN insulin increases LSNA via ERK signaling, possibly within the InsR‐responding neuron.Grant Funding Source: Supported by HL088552 and AHA.
Hydrogen peroxide modulates barium‐sensitive K+‐currents of nucleus tractus solitarii neurons (686.14)
Authors: Ostrowski Tim , Hasser Eileen , Heesch Cheryl , Kline David 
Published: June 2021

The nTS holds a vital role in cardiorespiratory reflexes as the first central integration site of chemosensitive afferents. Hypoxia‐reoxygenation over‐produces H2O2, a potent neuromodulator and reactive oxygen species. We previously found in rat brainstem slices that second‐order nTS neurons initially reduce excitability when exposed to 500 µM H2O2. This was due to a reversible hyperpolarization in resting membrane potential (RMP; ‐10 mV) and reduction in membrane resistance (Ri; ‐224 MΩ). Since these effects occur at RMP (~ ‐60 mV), we determined the effect of H2O2 on K+ channel conductance using voltage steps and ramps between ‐100 and ‐50 mV in nTS slices. H2O2 increased the slope of holding currents during steps by 1.31 ±0.35 nS (N=6, p蠄0.01). Such currents reversed at ‐75 mV, indicating greater K+ conductance. Augmented conductance (+ 0.49 ±0.18 nS; N=5, p蠄0.05) by H2O2 was also observed during voltage ramps. Conductance changes persisted during blockade of glutamate and GABAA receptors, confirming such effects were not secondary to synaptic activation. H2O2‐induced alterations of RMP, Ri and slope conductance were eliminated by barium (100 µM), a blocker of inward rectifying (IRK) and 2‐pore‐domain (K2P) K+ channels. Altogether, the H2O2 induced increase in barium‐sensitive K+ conductance is likely an immediate response to increased ROS and mediates decreased neuronal activity.Grant Funding Source: Supported by: RO1 HL098602, AHA 12POST11670002 (TDO).
Intracerebroventricular injection of Tityustoxin increases the cardiovascular parameters and renal sympathetic nerve activity (686.18)
Authors: Silva Fernanda , Marins Fernanda , Fontes Marco , de Menezes Rodrigo , Guidine Patrícia , Chianca Deoclécio 
Published: June 2021

The scorpion envenoming is an important public health problem in tropical and subtropical countries. Despite, clinical studies address the high sensitivity of the central nervous system to Titystoxin (TsTX) action, mainly in infants, few studies focus on the central action of the scorpion toxins. Because of this we aimed to assess if the cardiovascular parameters and renal sympathetic nerve activity (RSNA) could be altered by a central injection of a very low dose of TsTX (0.116µg), which is more than 20,000 times less concentrated than those used in peripheral experiments. Urethane anesthetized wistar male rats (n=5) were submitted to: 1) tracheostomy to airway maintenance, 2) arterial and vein femoral cannulation to measure the cardiovascular parameters and drugs infusions, 3) location of the left lateral ventricle to PBS and TsTX injection (1μl) and 4) isolation of renal nerve to measure the RSNA. Mean arterial pressure (MAP), Heart Rate (HR) and RSNA records were done before (20 min for baseline and PBS periods) and after TsTX injection (60 min). TsTX period was divided in: beginning (B), midlle (M) and final (F). Methods were approved by Ethical Committee (CEUA/UFOP:2011/46;2013/49). Results were expressed as mean ± SEM. Naturally, PBS did not changes the parameters. But, TsTX increased the MAP(Δ):(B)= 15±7, (M)=21±9, (F)= 21±12mmHg; p =0,0005; HR(Δ): (B)=45±19, (M)=74±22, (F)= 82± 25 bpm; p=0,0039 and (ΔRSNA,% of baseline: (B)=101±18; (M)=187±26, (F)= 254±38; p< 0,0001. These results indicate a high sensitivity of blood pressure and HR control nuclei and the huge RSNA responsiveness to the central action of a very low dose of TsTX.Grant Funding Source: Supported by UFOP, CAPES, FAPEMIG and CNPq
Angiotensin II receptor type‐1a knockdown in subfornical organ prevents sustained increase in mean arterial pressure associated with chronic intermittent hypoxia (686.20)
Authors: Saxena Ashwini , Little Joel , Nedungadi Thekkethil , Cunningham J 
Published: June 2021

Sleep apnea (SA) is associated with a sustained increase in mean arterial pressure (MAP) even during waking hours. Chronic intermittent hypoxia (CIH) models the hypoxemia associated with SA and produces elevated MAP during CIH and normoxia. Angiotensin II (Ang II) is implicated in the CIH associated increase in MAP. Subfornical organ (SFO), a forebrain circumventricular organ, lacks blood brain barrier and is a major site for the central effects of circulating Ang II. We investigated the effects of Ang II type 1a receptor knockdown (AT1aRKD) in the SFO on CIH hypertension in adult male rats. Adeno‐associated viral vectors carrying GFP and either AT1aR shRNA or scrambled shRNA (SCM) were injected in SFO. Using laser‐capture microdissection and qRT‐PCR of amino‐allyl RNA, AT1aRKD rats showed decreased SFO AT1aRmRNA in comparison with SCM rats (p<0.05). During light phase, the AT1aRKD rats exposed to CIH(3 min 10% O2 and 3 min room air cycles for 8 h during light phase for 7 d) exhibited significant increases in MAP vs. AT1aRKD‐Normoxia group (p<0.05). During the normoxic dark phase, there was no difference in MAP between CIH and normoxic AT1aRKD rats (p=0.69). SCM‐CIH group showed significant increase in MAP from SCM‐Normoxia group during light phase CIH (p<0.001) and the normoxic dark phase (p<0.001). Our data indicate that AT1aRs in SFO may play a role in the sustained increases in MAP during normoxia associated with CIH.Grant Funding Source: Supported by: P01HL088052‐05
Hering‐Breuer evoked regulation of respiratory rhythm variability in rats (686.25)
Authors: Dhingra Rishi , Galan Roberto , Dick Thomas 
Published: June 2021

Hering‐Breuer‐related afferent activity affects respiratory patterning in disparate ways: constant mechanical ventilation entrains the respiratory rhythm; yet removal of vagal feedback reduces respiratory rhythm variability. We hypothesize that these effects are mechanistically linked and test this hypothesis by closing the Hering Breuer Reflex feedback loop via rhythmic vagal nerve stimulation in situ before and after suppressing activity in the nucleus tractus solitarii (nTS) or Kölliker‐Fuse nuclei (KFn) by microinjection of muscimol, a GABAAR agonist. We measured feedback‐evoked entrainment of respiration and the variability of the rhythm in the presence or absence of periodic vagal feedback. Rhythmic vagal feedback evoked periods of entrainment interposed by phase slips. Analysis of respiratory rhythm variability revealed that vagal feedback amplified intrinsic respiratory rhythm variability via the transitions from a phase slip to stable entrainment. Suppressing nTS activity eliminated both entrainment and variability amplification. Suppressing KFn activity increased entrainment strength, reduced phase slip frequency and blunted variability amplification. We conclude that 1) Hering‐Breuer feedback inputs are sufficient to amplify respiratory variability via a noisy synchronization mechanism and 2) both entrainment and variability depend on KFn and nTS activity.Grant Funding Source: Supported by NS069220 and T32 HL007913
Nucleus tractus solitarii reactive oxygen species contribute to acute intermittent hypoxia‐induced long‐term facilitation of phrenic and splanchnic sympathetic nerve activity (686.26)
Authors: Ostrowski Daniela , Ruyle Brian , Allison Kleiber , Kline David , Heesch Cheryl , Hasser Eileen 
Published: June 2021

Cardiorespiratory neural networks undergo alterations in function (plasticity) that are critical to homeostasis but can be deleterious, as in obstructive sleep apnea (OSA). AIH in rats (10X: 45 sec of 10% O2 every 5 min) mimics cardiorespiratory changes as in OSA; prolonged increases in ventilatory/phrenic and sympathetic activity (AIH‐LTF) and augmented hypoxia (Hx) responses post‐AIH. The nTS integrates and modulates primary cardiorespiratory input and undergoes plasticity in response to changes in afferent input, including to Hx. nTS ROS are increased by intermittent Hx and important for plasticity. We hypothesized that nTS ROS contribute to AIH‐LTF and augmented Hx responses post‐AIH. Bilateral microinjection of the antioxidant catalase (CAT, 500 U/ml; 60 nl) in the nTS prior to each Hx bout during AIH attenuated AIH‐LTF for both integrated phrenic amplitude and splanchnic sympathetic nerve activity (%Δ: PhrA, Con=152±58, n=9; CAT=27±19, n=6; SSNA, Con=51±6, n=9; CAT=34±7, n=8). CAT also diminished augmented Hx responses post‐AIH (%Δ vs. Hx1st: PhrA, Con=76±37; CAT=14±22; SSNA, Con=90±11; CAT=50±13). In separate animals, chronically decreasing nTS ROS by injecting a viral vector overexpressing human catalase (AdCAT) also attenuated AIH‐LTF (%Δ: PhrA, Con=77±23, n=8; AdCAT=‐21±15, n=4; SSNA, Con=27±8; AdCAT=1±17). Data suggest nTS ROS contribute to phrenic and sympathetic AIH‐LTF. HL98602Grant Funding Source: Supported by HL98602
Angiotensin converting enzyme 1 knockdown in the median preoptic nucleus attenuates sustained diurnal hypertension following chronic intermittent hypoxia (686.29)
Authors: Faulk Katelynn , Nedungadi T. Prashant , Cunningham J. Thomas 
Published: June 2021

Chronic Intermittent Hypoxia (CIH) is a model for the arterial hypoxemia seen in sleep apnea and is associated with a sustained increase in blood pressure throughout the diurnal cycle. Studies indicate that the MnPO contributes to this sustained component of CIH hypertension that persists during normoxia. MnPO neurons from rats show increased expression of the transcription factor FosB following CIH. Dominant‐negative inhibition of a FosB splice variant in MnPO attenuates the sustained hypertension in CIH. We identified the pro‐hypertensive ACE1 as a possible FosB target gene that may contribute to the sustained hypertension seen in CIH. We tested this hypothesis using a viral vector to knockdown ACE1 in the MnPO. Isoflurane anesthetized adult male rats were microinjected in the MnPO with 500nl of an adeno‐associated virus containing GFP and either shRNA against ACE1 (shACE1) or a scrambled shRNA (shSCM). Changes in Mean arterial blood pressure (MAP) were recorded using radio telemetry. Rats were then exposed to CIH for 7 days through 3 minute periods of hypoxia (10% oxygen) and 3 minute periods of normoxia (21% oxygen) for 8 hours per day (0800‐1600 h). Normoxic controls were exposed to room air. Laser capture microdissection followed by qRT‐PCR showed that shACE1 significantly decreased ACE1 message in MnPO. During CIH exposure, MAP significantly increased in both shACE1 and shSCM treated rats. During the normoxic dark phase, knockdown of ACE1 in the MnPO statistically decreased the sustained MAP component of CIH as compared to shSCM controls (P<0.001). These results show that ACE1 in the MnPO contributes to the sustained hypertension seen in our CIH model.Grant Funding Source: P01 HL88052
Cortical and subcortical contributions to muscle sympathetic nerve activity in awake humans: a functional connectivity fMRI analysis (686.30)
Authors: Macefield Vaughan , James Cheree , Henderson Luke 
Published: June 2021

Purpose: Using direct microelectrode recordings of muscle sympathetic nerve activity concurrently with functional magnetic resonance imaging (fMRI) of the human brain, we have been able to identify the cortical and brainstem regions responsible for the generation of spontaneous muscle sympathetic nerve activity (MSNA). In the present study we aimed to determine the functional connectivity between these regions. Methods: A tungsten microelectrode was inserted percutaneously into a muscle fascicle of the common peroneal nerve, at the level of the fibular head, to record MSNA in 14 subjects. Gradient echo, echo planar fMRI was performed using a 3T scanner. Two hundred scans were collected continuously in a 4s‐ON, 4s‐OFF protocol. Total sympathetic burst amplitudes were measured from the RMS‐processed mean voltage amplitude during the 2‐4 s interval of the 4s‐OFF period, so as to account for the temporal location of the hypothalamus in the caudorostral scanning direction. A fixed‐effects group analysis (minimum cluster size=10 voxels, p<0.005) was performed to identify a volume of interest for use as a ‘seeding area’. A connectivity analysis was then performed (fixed‐effects, minimum cluster size=10 voxels, p<0.005) with the ventromedial hypothalamus being used as a ‘seeding area’. Results: The ventromedial hypothalamus showed positive relationships with the left dorsomedial hypothalamus and anterior insula, precuneus and right dorsolateral prefrontal cortex and rostroventral lateral medulla bilaterally. Conclusions: Spontaneous fluctuations in sympathetic nerve activity to muscle covaries with activity in multiple brain regions, supporting the idea that the hypothalamus contributes to the ongoing control of resting blood pressure and may be driving other brain regions involved in the control of MSNA.Grant Funding Source: NHMRC