bluuebunny/crossref_metadata_2025_split huggingface dataset:
Noradrenergic signaling in the retrotrapezoid nucleus differentially modulates breathing in anesthetized rats by alpha‐1 and alpha‐2 receptor dependent mechanisms
Authors: Oliveira Luiz M , Mulkey Daniel K , Moreira Thiago , Takakura Ana C 
Published: November 2023

Noradrenaline is a potent modulator of breathing that can increase or decrease respiratory activity by alpha‐1 or alpha‐2 receptors activation, respectively. The retrotrapezoid nucleus (RTN) is a region located in the rostral aspect of ventrolateral medulla and is known to contribute to central chemoreception, inspiration and active expiration. The aims of this study are to further investigate sources of catecholaminergic inputs to the RTN, as well as identify cardiorespiratory effects produced by activation of adrenergic receptors in this region. We identified a considerable number of the retrograde tracer FluorGold labeled cells (41 ± 8%) in the A7 region, suggesting the A7 is a major source of noradrenergic drive to the RTN. In urethane‐anesthetized, vagotomized and artificial ventilated male Wistar rats (260–290 g, n= 8–10/group), mean arterial pressure (MAP), diaphragm (DiaEMG) and abdominal (AbdEMG) muscle activities were recorded. Unilateral injection of noradrenaline produced a transient dose‐dependent (from 0.25 – 1 mM) inhibition of DiaEMG frequency (Δ = −10 ± 4; −14 ± 7 and −27 ± 11% of control) and amplitude (Δ = −41 ± 4.1; −48 ± 3% and −65 ± 2% of control), without changing MAP and AbdEMG. Unilateral injection of the alpha‐2 adrenergic and imidazoline receptors agonist moxonidine (20 μM) also produced a reduction in DiaEMG amplitude and frequency. The inhibition in the inspiratory activity produced by noradrenaline or moxonidine was completely blocked by the pretreatment with yohimbine (alpha‐2 receptors antagonist, 100 μM) in the RTN. We also found that unilateral RTN injection of phenylephrine (Phe, alpha‐1 adrenergic receptor agonist, 10 μM) increased DiaEMG amplitude by 62 ± 8% and frequency by 75 ± 18% and was able to elicit active expiration. The stimulatory effect on breathing produced by Phe was completely blocked by prior injection of prazosin (alpha‐1 receptor antagonist, 200 μM) into the RTN. We conclude that i) the pontine A7 region is a major source of cathecolamines to the RTN; ii) activation of alpha‐2 adrenergic receptors in the RTN inhibits respiratory activity; and iii) activation of alpha‐1 adrenergic receptors in the RTN increases inspiratory and expiratory activity. In related work, we have characterized the cellular and molecular mechanisms underlying noradrenaline modulation of RTN chemoreceptors (see abstract by Kuo et al.).Support or Funding InformationFAPESP, CNPq, CAPES/PROEX
Airway Deflation Activated Receptors Are Stimulated by Hypertonic Saline
Authors: Guardiola Juan , Proctor Mary , Yu Jerry 
Published: November 2023

Recently, deflation activated receptors (DARs) in the lung have been identified as a group of airway sensory receptors. DARs often share their afferents with rapidly adapting receptors (RARs) as well as slowly adapting pulmonary stretch receptors (SARs) to form a sensory unit. However, the afferent properties of DARs have not been well characterized. It has been reported that airway RAR units are stimulated, whereas typical SAR units (units do not respond to lung deflation) are not stimulated by hypertonic saline. Since RAR units are often share afferents with DARs, possibly, it is the DARs that are stimulated by hypertonic saline. The present study determines whether DARs can be stimulated by increased osmolarity. In anesthetized, open‐chest and artificially ventilated rabbits, we recorded single unit activities from typical SAR units and SAR units that respond to lung deflation (units contain DARs). We examined responses of these two groups to injection of hypertonic saline (8.1% sodium chloride, 0.1 ml) into receptive fields in the lung. Hypertonic saline decreased the activity of typical SARs, although not substantially. At baseline, activity of typical SAR units was 40.3 ± 5.4 imp/s (n=12). It decreased to 34.8 ± 4.7 imp/s (p<0.05) at 17.5 seconds after injection of hypertonic saline. On the other hand, hypertonic saline stimulated deflation activated SAR units significantly. Baseline activity increased from 15.9 ± 2.2 imp/s to its speak of 43.4 ± 10.0 imp/s (n=10, p<0.01) at 10.5 seconds after injection. The activity returned to the control level within a minute. Our results show that behavior of deflation activated and typical SAR units was different. The former, but not the latter, was stimulated by hypertonic saline. We conclude that DARs are stimulated by hypertonic saline.Support or Funding Information(Supported by a VA Merit Review Award PULM‐029‐10S)
Neurovascular Coupling is Coordinated by The Activation of Nitric Oxide Production in Astrocytes
Authors: Puebla Mariela D , Muñoz Manuel F , Figueroa Xavier 
Published: November 2023

Changes in neuronal activity must be coupled to proportional variations in the local cerebral blood flow to keep brain function. Then, an increase in synaptic activity leads to vasodilation of local parenchymal arterioles, which is achieved by a mechanism known as neurovascular coupling. Astrocytes mediate this communication mechanism through the propagation to the astrocytic end‐feet of an intracellular Ca2+ signaling initiated by neurotransmitters such as glutamate. ATP release through hemichannels formed by connexin 43 (Cx43) is thought to coordinate this signaling process. As astrocytes express the Ca2+‐dependent nitric oxide (NO)‐synthetizing enzymes eNOS and nNOS, and NO activates Cx43 hemichannels, we evaluated the participation of NO in the control of neurovascular coupling. Hemichannel activity was measured by recording ethidium uptake. In addition of hemichannels activity, changes in intracellular Ca2+ concentration and ATP release were also evaluated in primary cultures of astrocytes and vasomotor activity of cortex arterioles was recorded in rat brain slices. Stimulation with glutamate or the glutamate metabotropic receptor agonist, 1‐aminocyclopentane‐trans‐1,3‐dicarboxylic acid (t‐ACPD), induced hemichannel activation, an increase in astrocytic Ca2+ concentration, ATP release and vasodilation of parenchymal arterioles; responses that were blocked by the inhibition of NO production with NG‐nitro‐L‐arginine (L‐NA). Blockade of hemichannels with the connexin blocking peptide 37, 43Gap27 inhibited the increase in Ca2+, but not ATP release. Interestingly, the inhibition of purinergic receptor with pyridoxalphosphate‐6‐azophenyl‐2′,4′‐disulfonic acid (PPADS) also blocked the activation of connexin hemichannel and the Ca2+ signaling observed in response to glutamate. In addition, the increase in ethidium uptake, intracellular Ca2+ concentration and ATP release induced by glutamate were abolished by the calcium homeostasis modulator 1 (CALHM1) channel blocker, ruthenium red. Consistent with the participation of NO in this response, glutamate and SNAP, a NO donor, evoked the S‐nitrosylation of CALHM1 channels. These results suggest that NO production plays a central role in the control of astrocyte‐mediated neurovascular coupling through activation of CALHM1 channels by S‐nitrosylation and the further opening of Cx43 hemichannel via ATP release and purinergic receptor activationSupport or Funding InformationFONDECYT 1150530
GABAB receptor plasticity in corticotrophin releasing hormone neurons in the paraventricular nucleus during chronic unpredictable stress
Authors: Gao Yonggang , Zhou Jing‐Jing , Li De‐Pei 
Published: November 2023

GABAB (γ‐aminobutytic acid type B) receptor is important in the regulation of neuronal excitability. Chronic stress leads to hyperactivity of corticotrophin releasing hormone (CRH) neurons. However, the role of GABAB receptors in the regulation of CRH neurons in paraventricular nucleus (PVN) of the hypothalamus in chronic stress is not known. Here, we determined pre‐ and postsynaptic GABAB receptor function in identified PVN‐CRH neurons expressing eGFP driven by crh premotor‐driven eGFP. Whole cell patch‐clamp recording were performed on PVN‐CRH neurons in brain slices from unstressed rats and rats with chronic unpredictable mild stress (CUMS). Bath application of the GABAB receptor agonist baclofen induced a significant lesser reduction of firing activity in PVN‐CRH neurons in CUMS than in unstressed rats. Furthermore, baclofen induced lesser outward currents in PVN‐CRH neurons in CUMS than in unstressed rats. Baclofen‐induced currents were eliminated by inclusion of GDP‐β‐s in internal recording solution or blocking G protein‐coupled inwardly‐rectifying K (GIRK) channels with tertiapin. GABAB1 receptor expression level in the PVN was significantly decreased in CUMS than in unstressed rats. Baclofen produced significant greater inhibition of the frequency of glutamatergic excitatory postsynaptic currents (EPSCs) and GABAergic inhibitor postsynaptic currents (IPSCs) without affecting the amplitude of EPSCs and IPSCs in PVN‐CRH neurons in CUMS and unstressed rats. These data suggest that down‐regulated postsynaptic GABAB receptor contributes to suppressing GABAB‐mediated inhibition of PVN‐CRH neurons in chronic stress.Support or Funding InformationNIMH grants MH096086.
Androgenic Regulation of Sex Differences in Cortical Thickness of the Developing Mouse Brain
Authors: Miyasaki Dillon , Ramos Layla , Tsai Houng‐Wei 
Published: November 2023

The cerebral cortex plays an important role in complex cognitive and social behaviors. Considerable evidence suggests that many of those are sexually dimorphic, but the neural mechanism underlying sex differences in cortical function still remains unclear. An earlier study showed greater cortical thickness in three areas of the parietal cortex of adult male mice compared with females, which seemed to be influenced by gonadal steroids, not sex chromosomal complement. Since activation of androgen receptor (AR) by perinatal testosterone secreted by the developing testes increases the in the number of calbindin‐positive neurons in the sexually dimorphic nucleus of the male preoptic area, a hypothalamic region that controls male copulatory behaviors, we thus hypothesized that AR might also be responsible for masculinization of the mouse cerebral cortex. To test our hypothesis, we collected the whole brains (n=4–6 per group) of wild‐type male and female mouse pups as well as their littermates with testicular feminization mutation (Tfm), lacking functional AR, on postnatal days 21–24. Their brains were post‐fixed in 4% paraformaldehyde, serially sectioned, and stained with crystal violet. After the slides were cover‐slipped, measurement of cortical thickness in the primary somatosensory cortex, secondary somatosensory cortex, secondary motor cortex, and entorhinal cortex was taken under a light microscope using ImageJ. Among these brain regions, our preliminary data showed a significant effect of experimental group on cortical thickness in the entorhinal cortex only (P = 0.01). While wild‐type male mice had a thicker entorhinal cortex than wild‐type females, the cortical thickness in Tfm mice was intermediate between the wild‐type males and females and did not differ significantly from either of those groups. Our preliminary data suggests an important role for the AR in sexual differentiation of brain structure in the mouse entorhinal cortex during development.Support or Funding InformationThis work was supported by National Institutes of Health Grant SC3‐GM102051.
Sex‐specific Effect of Androgen on SFSWAP Expression in the Developing Mouse Cortex and Hippocampus
Authors: Ridder Aaron , Lee YuanYu , Tsai Houng‐Wei 
Published: November 2023

The cortex and hippocampus both are important for the control of complex cognitive and social behaviors, and considerable evidence suggests that these functions are sexually dimorphic. However, neural mechanisms underlying these differences are still not well understood. We have previously used immunoblotting to detect splicing factor suppressor of white apricot (SFSWAP) protein at a molecular weight of 105 kDa in the developing mouse cortex/hippocampus. We then measured cortical/hippocampal SFSWAP levels in male and female mice collected on the day of birth (PN0), and 7 (PN7), and 14 (PN14), and 21 (PN21) days after birth and found higher SFSWAP expression in females than males at all ages except PN0. Since androgens masculinize the brain nuclei of the hypothalamus and amygdala underlying male‐specific behaviors, we thus hypothesized that sexually dimorphic SFSWAP expression in the cerebral cortex/hippocampus might be similarly regulated by testosterone. To test our hypothesis, we treated male and female pups with either vehicle (0.05 ml sesame oil) or testosterone propionate (TP, 0.1 mg dissolved in 0.05 ml sesame oil) daily for three days starting on PN21. Their cortex/hippocampus (n= 6 per group) was collected 3–5 h after the last injection, followed by protein extraction and immunoblotting for SFSWAP. While a trend of female‐biased SFSWAP upregulation was found in vehicle‐treated groups, our results showed that TP decreased SFSWAP levels in female pups (0.67 ± 0.07 vs. 1.00 ± 0.08, p<0.05), not males. The observation of pharmacological effects of testosterone on SFSWAP downregulation in females suggests that SFSWAP expression might be mediated directly by androgen receptor or indirectly by estrogen receptors after it is converted to estradiol locally by aromatase. Further, the sex‐specific androgenic regulation of SFSWAP expression in the cortex/hippocampus could be due to the sex chromosome complement and/or the organizational effect of perinatal steroids occurring around birth.Support or Funding InformationThis work was supported by National Institutes of Health Grant SC3‐GM102051.
Saporin Inhibits Adonis‐biotin Stimulation of Proliferation of Cells of Caudate Nucleus of Newborn Lambs
Authors: McBride Shaemion , Ibe Basil Obijiaku , Rajaee Arezoo , Koos Brian 
Published: November 2023

The subventricular zone of the caudate nucleus (CN) contains proliferating progenitor stem cells that may play a role in the greater plasticity of the developing brain. CN cells involved in this reorganizational capacity have not been defined. Rodents are used extensively to study developmental disorders, while larger mammals are seldom studied. We hypothesized that the reorganizational ability of the CN involves the proliferation of CN cells. Primary cells of CN of newborn lambs 3–8 days old were used to study the proliferative potential of CN in vitro. We used Adonis‐biotin, a cell permeable Adonis analog and the ribosome‐inactivating protein conjugate Streptavidin‐SAP (Saporin) as a control for cell growth stimulating properties of the Adonis‐biotin. Adonis‐biotin and Saporin modulate cell proliferation by interacting with cell DNA. Cells in culture were treated with different concentrations (nM); 0.1, 1.0, and 10.0 of Adonis‐biotin, Saporin and equimolar mixture of the Adonis‐biotin and Saporin and the culture medium as control for cell proliferation. Treated cells were incubated at 37°C for 4 days. Cell proliferation was determined each day by cell counting. Effect of these treatments on cell proliferation was also studied by DNA synthesis and immunocytochemistry with DAPI staining. Adonis‐biotin stimulation of cell proliferation was both concentration and time dependent. Treatment of cells with Saporin specifically inhibited cell proliferation such that the co‐treatment with Adonis‐biotin did not abrogate the inhibitory effect of Saporin on CN cell proliferation, suggesting that Saporin had profound toxicity to the cell. This observation was supported by DAPI staining where Adonis‐biotin, but not Saporin, treatment stimulated cell proliferation. Taken together this study shows the involvement of CN cells in the plasticity of basal ganglia of the developing brain.Support or Funding InformationGrant #20842 from Department of Obstetrics and Gynecology, UCLA.
Cytoprotective and Anti‐Glycation Defenses in Porcine Brain after Cardiac Arrest and Cardiocerebral Resuscitation
Authors: Nguyen Anh Quynh , Ryou Myoung‐Gwi , Hollrah Roger A , Williams Arthur G , Scott Gary F , Olivencia‐Yurvati Albert H , Mallet Robert T 
Published: November 2023

BackgroundCardiac arrest (CA) is often lethal, and survivors often face sequelae that greatly impact quality of life due to brain injury inflicted by ischemia‐reperfusion. Effective cardiocerebral resuscitation (CCR) is essential for survival and recovery from CA. The complexity of the injury cascades ignited by CA and the presence of the blood‐brain barrier challenge the development of pharmacological interventions to protect the brain. Our goal is to identify a blood‐brain barrier‐permeable intervention that mitigates CA‐induced brain damage and, thus, fosters neurological recovery. Pyruvate, a cellular metabolite, energy substrate and antioxidant, has been found to be neuroprotective in a rat stroke model via induction of the cytoprotective cytokine erythropoietin (EPO) [Stroke 2012; 43:1101–1107].HypothesisPyruvate treatment during CCR and post resuscitation decreases brain injury by upregulating cellular defense mechanisms including hypoxia inducible factor‐1α (HIF‐1α), EPO, the product of HIF‐1 α's gene program, and glyoxalase‐1, the principal component of the brain's defenses against the powerful glycating agent and glycolytic byproduct, methylglyoxal.MethodsYorkshire swine (25–35 kg, both genders) were subjected to sham protocol (n = 6) or pacing‐induced CA (n = 12). CCR was administered by precordial chest compressions (100/min) at 10–14 min CA, and transthoracic countershocks were applied to restore sinus rhythm. NaCl (n = 6) or Na‐pyruvate (n = 6) was infused iv (0.1 mmol/kg/min) during CCR and the first 60 min recovery. At 4 h recovery, brain was cross‐perfused with 0.9% NaCl, and then brain biopsies were freeze‐clamped for biochemical analysis or fixed in 10% formalin for immunohistochemistry.ResultsIn hippocampus, activity of the oxyradical‐sensitive TCA cycle enzyme aconitase fell by 50% (P < 0.05) during CA + CPR with NaCl and Na‐pyruvate treatment, while no appreciable difference was detected in the cerebellum. There were no statistically significant differences in HIF‐1α or EPO contents in the hippocampus among the sham and CA groups. Similar trends were observed in the cerebellum except for EPO content, which fell by 40% (P<0.05) regardless of treatment. In contrast, pyruvate increased glyoxalase‐1 activity threefold in cerebral cortex (P<0.01).ConclusionCardiac arrest inactivates aconitase and depletes cytoprotective EPO in ischemia‐sensitive brain regions. Although pyruvate intervention during CPR and the initial 60 min recovery did not produce sustained protection or upregulation of aconitase or EPO, it produced robust augmentation of glyoxalase‐1, thereby bolstering the brain's defenses against the glycating metabolite methylglyoxal.Support or Funding InformationNINDS Support: NS076975
Chronic Mild Stress Increases Baseline Renal Sympathetic Nerve Activity and the Response to Acute Stressors in Conscious Rats
Authors: Das Shibandri , Li Cailian , Chen Haiping , Rossi Noreen F. 
Published: November 2023

Depression is a non‐traditional risk factor for cardiovascular morbidity and mortality. Increased sympathetic tone is also recognized as deleterious to cardiovascular health. Chronic mild unpredictable stress paradigm (CMS) is a validated model of depression that has been associated with cardiovascular dysfunction in rats. We hypothesized that rats exposed to CMS will have higher arterial pressure and renal sympathetic nerve activity (RSNA) and enhanced responses to acute stressors. Male Sprague Dawley rats were equipped with telemetry transmitters for hemodynamic monitoring and subjected to 4 weeks of CMS or standard housing (control). During the last week, rats were equipped with telemetry transmitters for renal nerve recording. Baseline RSNA was obtained a minimum of 3 days after completion of CMS protocol and the rats were subjected to air jet stress and nasopharygeal reflex testing. Baseline arterial pressure was higher in CMS rats. Baseline RSNA was 0.80 ± 0.05 mV.s in control vs 1.20 ± 0.14 mV.sec in CMS rats (P < 0.05). Peak responses to either air jet stress or nasopharyngeal stimulation were significantly higher in the CMS rats. Although the latencies of the responses were shorter and the duration of the responses were longer in the CMS group, these did not achieve significance. The area under the curve (AUC = latency × duration) for air jet stress was 82% greater for air jet stress and 362% greater for nasopharygeal stimulation in the CMS vs control rats (P < 0.05 for both vs control). These results support the concept that rats subjected to a chronic unpredictable stress paradigm that models depression display higher basal sympathetic nerve activity and a more robust response to acute stress. This enhanced sympathetic tone and neuroexcitability may contribute to increased cardiovascular risk.Support or Funding InformationVA Merit Grant to NFR
Altered Activity in Efferent Projection Sites of the Brain Orexin System is Associated with Poor Cardiovascular Adaptability in an Animal Model of Hypertension and Attention Deficit/Hyperactivity Disorder (ADHD)
Authors: Ahmari Niousha , Simons Chloe , Watkins Jaqueline , Long Maureen , Febo Marcelo , Zubcevic Jasenka , Hayward Linda 
Published: November 2023

The neuropeptide orexin has recently been shown to be dysregulated in the spontaneously hypertensive rat (SHR), an animal model of essential hypertension. The SHR has also been proposed as a model of ADHD. The present study was undertaken to determine whether regional differences in brain activation could be linked to differences in behavior or cardiovascular reactivity in the SHR when compared to normotensive rats (WKY; n=3–10/group). Manganese‐enhanced MRI of naïve animals identified that multiple efferent projection sites of the orexin system, including the hippocampus (CA1 and CA3, P<0.01) and the midbrain (central gray, dorsal raphe, ventral tegmental nucleus) had significantly (P<0.05) lower activity in the SHR vs WKY, with the exception of locus coeruleus which had elevated activity (P<0.02). In object recognition and social interaction tests, the SHRs generally spent less time interacting than WKYs. On the elevated plus maze test, SHR spent twice the time in the open arm field. This was paralleled by a similar initial rise in blood pressure (22+/−1 mmHg) and heart rate between strains (165+/−10 bpm). By the end of the 5 minute test however, WKY values returned to baseline while the SHR blood pressure remained elevated (+3 vs +20 mmHg). These results support the link between heightened activity in locus coeruleus (a primary target of the orexin system), hypertension, and behavioral markers of ADHD, and raise a novel prospect that reduced activity in other midbrain regions may also be linked to altered system function/adaptation in the SHR.Support or Funding InformationUF College of Veterinary Medicine Research Award (ML) & AHA 14SDG18300010 (JZ)