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Purnell BS, Petrucci AN, Li R, Buchanan GF. Effect of adenosinergic manipulations on amygdala-kindled seizures in mice: Implications for sudden unexpected death in epilepsy. Epilepsia 2024. [PMID: 38980980 DOI: 10.1111/epi.18059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/11/2024]
Abstract
OBJECTIVE Sudden unexpected death in epilepsy (SUDEP) results in more years of potential life lost than any neurological condition with the exception of stroke. It is generally agreed that SUDEP happens due to some form of respiratory, cardiac, and electrocerebral dysfunction following a seizure; however, the mechanistic cause of these perturbations is unclear. One possible explanation lies with adenosinergic signaling. Extracellular levels of the inhibitory neuromodulator adenosine rapidly rise during seizures, a countermeasure that is necessary for seizure termination. Previous evidence has suggested that excessive adenosinergic inhibition could increase the risk of SUDEP by silencing brain areas necessary for life, such as the respiratory nuclei of the brainstem. The goal of this investigation was to further clarify the role of adenosine in seizure-induced respiratory and electrocerebral dysfunction. METHODS To determine the role of adenosine in postictal physiological dysregulation, we pharmacologically manipulated adenosine signaling prior to amygdala-kindled seizures in mice while recording electroencephalogram (EEG), electromyogram, and breathing using whole body plethysmography. The adenosinergic drugs used in this study included selective and nonselective adenosine receptor antagonists and inhibitors of adenosine metabolism. RESULTS We found that high doses of adenosine receptor antagonists caused some seizures to result in seizure-induced death; however, counterintuitively, animals in these conditions that did not experience seizure-induced death had little or no postictal generalized EEG suppression. Inhibitors of adenosine metabolism had no effect on postictal breathing but did worsen some postictal electrocerebral outcomes. SIGNIFICANCE The unexpected effect of high doses of adenosine antagonists on seizure-induced death observed in this study may be due to the increase in seizure severity, vasoconstriction, or phosphodiesterase inhibition caused by these drugs at high doses. These findings further clarify the role of adenosine in seizure-induced death and may have implications for the consumption of caffeine in epilepsy patients and the prevention of SUDEP.
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Affiliation(s)
- Benton S Purnell
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Alexandra N Petrucci
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Rui Li
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Gordon F Buchanan
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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Multi-target Natural and Nature-Inspired Compounds against Neurodegeneration: A Focus on Dual Cholinesterase and Phosphodiesterase Inhibitors. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11115044] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Alzheimer’s disease is a memory-related neurodegenerative condition leading to cognitive impairment. Cholinergic deficit, together with other underlying mechanisms, leads the to onset and progression of the disease. Consequently, acetylcholinesterase inhibitors are used for the symptomatic treatment of dementia, even if limited efficacy is observed. More recently, some specific phosphodiesterase isoforms emerged as promising, alternative targets for developing inhibitors to contrast neurodegeneration. Phosphodiesterase isoforms 4, 5 and 9 were found to be expressed in brain regions that are relevant for cognition. Given the complex nature of Alzheimer’s disease and the combination of involved biochemical mechanisms, the development of polypharmacological agents acting on more than one pathway is desirable. This review provides an overview of recent reports focused on natural and Nature-inspired small molecules, or plant extracts, acting as dual cholinesterase and phosphodiesterase inhibitors. In the context of the multi-target directed ligand approach, such molecules would pave the way for the development of novel agents against neurodegeneration. More precisely, according to the literature data, xanthines, other alkaloids, flavonoids, coumarins and polyphenolic acids represent promising scaffolds for future optimization.
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Shoemaker A, Steelman K, Srbu R, Bell HJ. Disparity in the effect of morphine on eupnea and gasping in anesthetized spontaneously breathing adult rats. Am J Physiol Regul Integr Comp Physiol 2020; 319:R526-R540. [PMID: 32903040 DOI: 10.1152/ajpregu.00031.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The goal of this study was to examine the effects of systemic morphine on the pattern and morphology of gasping breathing during respiratory autoresuscitation from transient anoxia. We hypothesized that systemic morphine levels sufficient to cause significant depression of eupnea would also cause depression of gasping breathing. Respiratory and cardiovascular variables were studied in 20 spontaneously breathing pentobarbital-anaesthetized adult male rats. Sham (saline) injections caused no significant change in resting respiratory or cardiovascular variables (n = 10 rats). Morphine, on the other hand, caused significant depression of eupneic breathing, with ventilation and peak inspiratory flow decreased by ∼30-60%, depending on the background condition (n = 10 rats). In contrast, morphine did not depress gasping breathing. Duration of primary apnea, time to restore eupnea, the number and amplitude of gasping breaths, average and maximum peak flows, and volume of gasping breaths were not significantly different postinjection in either condition. Blood pressures were all significantly lower following morphine injection at key time points in the process of autoresuscitation. Last, rate of successful recovery from anoxia was 80% in the morphine group (8/10 rats) compared with 100% (10/10 rats) in the sham group, postinjection. We conclude that the mechanisms and/or anatomic correlates underlying generation of gasping rhythm are distinct from those underlying eupnea, allowing gasping to remain robust to systemic morphine levels causing significant depression of eupnea. Morphine nevertheless decreases likelihood of recovery from transient anoxia, possibly as a result of decreased tissue perfusion pressures at critical time points during the process of respiratory autoresuscitation.
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Affiliation(s)
- Amanda Shoemaker
- Central Michigan University College of Medicine, Mt. Pleasant, Michigan
| | - Kevin Steelman
- Central Michigan University College of Medicine, Mt. Pleasant, Michigan
| | - Rebeka Srbu
- Central Michigan University College of Medicine, Mt. Pleasant, Michigan
| | - Harold J Bell
- Central Michigan University College of Medicine, Mt. Pleasant, Michigan
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Kinney HC, Haynes RL. The Serotonin Brainstem Hypothesis for the Sudden Infant Death Syndrome. J Neuropathol Exp Neurol 2020; 78:765-779. [PMID: 31397480 DOI: 10.1093/jnen/nlz062] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/28/2019] [Accepted: 06/25/2019] [Indexed: 01/04/2023] Open
Abstract
The sudden infant death syndrome (SIDS) is the leading cause of postneonatal infant mortality in the United States today, with an overall rate of 0.39/1000 live births. It is defined as the sudden and unexpected death of an infant <12 months of age that remains unexplained after a complete autopsy, death scene investigation, and review of the clinical history. The serotonin brainstem hypothesis has been a leading hypothesis for SIDS over the last 2 decades. Our laboratory has studied this hypothesis over time with a variety of tissue techniques, including tissue receptor autoradiography, high performance liquid chromatography, Western blot analysis, immunocytochemistry, and proteomics. The purpose of this article is to review the progress in our laboratory toward supporting this hypothesis. We conclude that an important subset of SIDS infants has serotonergic abnormalities resulting from a "core lesion" in the medullary reticular formation comprised of nuclei that contain serotonin neurons. This lesion could lead to a failure of protective brainstem responses to homeostatic challenges during sleep in a critical developmental period which cause sleep-related sudden death.
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Affiliation(s)
- Hannah C Kinney
- Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Robin L Haynes
- Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts
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5
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Erickson JT. Central serotonin and autoresuscitation capability in mammalian neonates. Exp Neurol 2020; 326:113162. [DOI: 10.1016/j.expneurol.2019.113162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 11/04/2019] [Accepted: 12/23/2019] [Indexed: 01/08/2023]
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Dosumu-Johnson RT, Cocoran AE, Chang Y, Nattie E, Dymecki SM. Acute perturbation of Pet1-neuron activity in neonatal mice impairs cardiorespiratory homeostatic recovery. eLife 2018; 7:37857. [PMID: 30350781 PMCID: PMC6199134 DOI: 10.7554/elife.37857] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/09/2018] [Indexed: 12/02/2022] Open
Abstract
Cardiorespiratory recovery from apneas requires dynamic responses of brainstem circuitry. One implicated component is the raphe system of Pet1-expressing (largely serotonergic) neurons, however their precise requirement neonatally for homeostasis is unclear, yet central toward understanding newborn cardiorespiratory control and dysfunction. Here we show that acute in vivo perturbation of Pet1-neuron activity, via triggering cell-autonomously the synthetic inhibitory receptor hM4Di, resulted in altered baseline cardiorespiratory properties and diminished apnea survival. Respiratory more than heart rate recovery was impaired, uncoupling their normal linear relationship. Disordered gasp recovery from the initial apnea distinguished mice that would go on to die during subsequent apneas. Further, the risk likelihood of apnea-related mortality associated with suppression of Pet1 neurons was higher for animals with baseline elevated ventilatory equivalents for oxygen. These findings establish that Pet1 neurons play an active role in neonatal cardiorespiratory homeostasis and provide mechanistic plausibility for the serotonergic abnormalities associated with SIDS. Our survival depends on our heart and lungs working together to supply our cells with oxygen and remove carbon dioxide waste. The brain coordinates this process by controlling the activity of the heart and lungs. Yet sometimes a person may experience an event called an apnea and briefly stop breathing. If this happens, oxygen levels in the body fall while carbon dioxide levels rise. This in turn triggers a recovery process called autoresuscitation, which includes a series of large breaths or gasps, and each gasp is accompanied by increased heart rate due to specialized parts of the nervous system. This response usually restores normal breathing. Failure of autoresuscitation may underlie many cases of sudden infant death syndrome, or SIDS (also known as “cot death” or “crib death”). SIDS is the leading cause of death in young infants in the western world, and many infants who die from SIDS show abnormalities in the brain cells that produce a chemical called serotonin. Evidence suggests that serotonin helps control breathing. This raised the question: does the autoresuscitation recovery response rely on serotonin-producing neurons? To find out, Dosumu-Johnson et al. used one-week-old mouse pups that had been genetically engineered to respond to an injected drug by rapidly inhibiting their serotonin neurons. These animals are about the same age in mouse terms as infants at greatest risk for SIDS (~2-4 months of age). Inhibiting serotonin neurons made it harder for the mouse pups to recover from artificially induced apneas. Although their heart rate showed largely normal recovery – at least at first – their breathing did not. They took fewer gasps, and were more likely to die following such episodes. These findings shed new light on how young animals control their breathing and heart rate when mounting an autoresuscitation recovery from an apnea. The observed uncoupling of breathing and heart rate recovery responses suggests that different brain cells and circuits control the two. The results also suggest that abnormalities in the activity of serotonin neurons may make infants more susceptible to SIDS. As well as offering a possible explanation to families who have lost a child to SIDS, these findings could be used to develop screening tools to identify other infants at risk. They also point to potential cellular targets for drugs that could ultimately help prevent further cases.
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Affiliation(s)
| | - Andrea E Cocoran
- Department of Molecular & Systems Biology, The Geisel School of Medicine at Dartmouth, Hanover, United States
| | - YoonJeung Chang
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Eugene Nattie
- Department of Molecular & Systems Biology, The Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Susan M Dymecki
- Department of Genetics, Harvard Medical School, Boston, United States
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Sun JJ, Nanu R, Ray RS. A low cost, simplified, and scaleable pneumotachograph and face mask for neonatal mouse respiratory measurements. J Pharmacol Toxicol Methods 2017; 86:1-11. [PMID: 28213294 DOI: 10.1016/j.vascn.2017.02.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 02/07/2017] [Accepted: 02/13/2017] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Neonatal respiratory disorders are a leading cause of perinatal mortality due to complications resulting from premature births and prenatal exposure to drugs of abuse, but optimal treatments for these symptoms are still unclear due to a variety of confounds and risk factors. Mouse models present an opportunity to study the underlying mechanisms and efficacy of potential treatments of these conditions with controlled variables. However, measuring respiration in newborn mice is difficult and commercial components are expensive and often require modification, creating a barrier and limiting our understanding of the short and long-term effects of birth complications on respiratory function. METHODS Here, we present an inexpensive and simple flow through pneumotachograph and face mask design that can be easily scaled for parallel, high-throughput assays measuring respiration in neonatal mouse pups. The final apparatus consists of three main parts: a water-jacketed chamber, an integrated support tray for the pup, and a pneumotachograph consisting of a two side-arm air channel that is attached to a pressure transducer. RESULTS The pneumotach showed a linear response and clean, steady respiratory traces in which apneas and sighs were clearly visible. Administration of caffeine in P0.5 CD1 wildtype neonates resulted in an increase in tidal volume, minute ventilation, and minute ventilation normalized to oxygen consumption as well as a decrease in periodic instability. DISCUSSION The described methods offer a relatively simple and inexpensive approach to constructing a pneumotachograph for non-invasive measurements of neonatal mouse respiration, enhancing accessibility and enabling the high-throughput and parallel characterizations of neonatal respiratory disorders and potential pharmacological therapies.
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Affiliation(s)
- Jenny J Sun
- Baylor College of Medicine, Department of Neuroscience, Room T707, 1 Baylor Plaza, Houston, TX 77030, United States.
| | - Roshan Nanu
- Baylor College of Medicine, Department of Neuroscience, Room T707, 1 Baylor Plaza, Houston, TX 77030, United States
| | - Russell S Ray
- Baylor College of Medicine, Department of Neuroscience, Room T703, 1 Baylor Plaza, Houston, TX 77030, United States.
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McDonald FB, Chandrasekharan K, Wilson RJA, Hasan SU. Interactive effects of maternal cigarette smoke, heat stress, hypoxia, and lipopolysaccharide on neonatal cardiorespiratory and cytokine responses. Am J Physiol Regul Integr Comp Physiol 2016; 311:R1113-R1124. [PMID: 27733384 DOI: 10.1152/ajpregu.00062.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 10/03/2016] [Accepted: 10/06/2016] [Indexed: 11/22/2022]
Abstract
Maternal cigarette smoke (CS) exposure exhibits a strong epidemiological association with Sudden Infant Death Syndrome, but other environmental stressors, including infection, hyperthermia, and hypoxia, have also been postulated as important risk factors. This study examines whether maternal CS exposure causes maladaptations within homeostatic control networks by influencing the response to lipopolysaccharide, heat stress, and/or hypoxia in neonatal rats. Pregnant dams were exposed to CS or parallel sham treatments daily for the length of gestation. Offspring were studied at postnatal days 6-8 at ambient temperatures (Ta) of 33°C or 38°C. Within each group, rats were allocated to control, saline, or LPS (200 µg/kg) treatments. Cardiorespiratory patterns were examined using head-out plethysmography and ECG surface electrodes during normoxia and hypoxia (10% O2). Serum cytokine concentrations were quantified from samples taken at the end of each experiment. Our results suggest maternal CS exposure does not alter minute ventilation (V̇e) or heart rate (HR) response to infection or high temperature, but independently increases apnea frequency. CS also primes the inflammatory system to elicit a stronger cytokine response to bacterial insult. High Ta independently depresses V̇e but augments the hypoxia-induced increase in V̇e Moreover, higher Ta increases HR during normoxia and hypoxia, and in the presence of an immune challenge, increases HR during normoxia, and reduces the increase normally associated with hypoxia. Thus, while most environmental risk factors increase the burden on the cardiorespiratory system in early life, hyperthermia and infection blunt the normal HR response to hypoxia, and gestational CS independently destabilizes breathing by increasing apneas.
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Affiliation(s)
- Fiona B McDonald
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Faculty of Medicine, University of Calgary, Alberta, Canada; and
| | - Kumaran Chandrasekharan
- Section of Neonatal-Perinatal Medicine, Department of Pediatrics, Faculty of Medicine, Health Sciences Centre, University of Calgary, Alberta, Canada
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Faculty of Medicine, University of Calgary, Alberta, Canada; and
| | - Shabih U Hasan
- Section of Neonatal-Perinatal Medicine, Department of Pediatrics, Faculty of Medicine, Health Sciences Centre, University of Calgary, Alberta, Canada
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Krause A, Nowak Z, Srbu R, Bell H. Respiratory autoresuscitation following severe acute hypoxemia in anesthetized adult rats. Respir Physiol Neurobiol 2016; 232:43-53. [DOI: 10.1016/j.resp.2016.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 06/28/2016] [Accepted: 06/30/2016] [Indexed: 01/16/2023]
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Goldstein RD, Kinney HC, Willinger M. Sudden Unexpected Death in Fetal Life Through Early Childhood. Pediatrics 2016; 137:e20154661. [PMID: 27230764 PMCID: PMC4894250 DOI: 10.1542/peds.2015-4661] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/07/2016] [Indexed: 11/24/2022] Open
Abstract
In March 2015, the Eunice Kennedy Shriver National Institute of Child Health and Human Development held a workshop entitled "Sudden Unexpected Death in Fetal Life Through Early Childhood: New Opportunities." Its objective was to advance efforts to understand and ultimately prevent sudden deaths in early life, by considering their pathogenesis as a potential continuum with some commonalities in biological origins or pathways. A second objective of this meeting was to highlight current issues surrounding the classification of sudden infant death syndrome (SIDS), and the implications of variations in the use of the term "SIDS" in forensic practice, and pediatric care and research. The proceedings reflected the most current knowledge and understanding of the origins and biology of vulnerability to sudden unexpected death, and its environmental triggers. Participants were encouraged to consider the application of new technologies and "omics" approaches to accelerate research. The major advances in delineating the intrinsic vulnerabilities to sudden death in early life have come from epidemiologic, neural, cardiac, metabolic, genetic, and physiologic research, with some commonalities among cases of unexplained stillbirth, SIDS, and sudden unexplained death in childhood observed. It was emphasized that investigations of sudden unexpected death are inconsistent, varying by jurisdiction, as are the education, certification practices, and experience of death certifiers. In addition, there is no practical consensus on the use of "SIDS" as a determination in cause of death. Major clinical, forensic, and scientific areas are identified for future research.
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Affiliation(s)
- Richard D Goldstein
- Department of Psychosocial Oncology and Palliative Care, Dana-Farber Cancer Institute, Department of Medicine, and
| | - Hannah C Kinney
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; and
| | - Marian Willinger
- Pregnancy and Perinatology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
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Fewell JE, Lun R. Adenosine A1-receptor blockade impairs the ability of rat pups to autoresuscitate from primary apnea during repeated exposure to hypoxia. Physiol Rep 2015; 3:3/8/e12458. [PMID: 26272732 PMCID: PMC4562557 DOI: 10.14814/phy2.12458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Failure of gasping to bring about autoresuscitation from hypoxia-induced apnea has been suggested to play a role in sudden unexpected infant death. Little is known, however, about factors that influence the ability of gasping to restore life during severe hypoxia in newborns. Given that adenosine modulates cardiac function during hypoxia-induced apnea and that cardiac dysfunction plays a role in mediating autoresuscitation failure, the present experiments were carried out on 34, 5- to 6-, and 10- to 11-day-old rat pups to investigate their ability to autoresuscitate from hypoxia-induced apnea during repeated exposure to hypoxia after adenosine A1-receptor blockade. Each pup was placed into a temperature-controlled chamber regulated to 37 ± 1°C and repeatedly exposed to an anoxic gas mixture (97% N2 and 3% CO2) until the occurrence of autoresuscitation failure. One group was studied following administration of the selective adenosine A1-receptor antagonist 8-Cyclopentyl-1,3,-dipropylxanthine (DPCPX) and one group was studied following vehicle. DPCPX significantly attenuated bradycardia during hypoxia-induced apnea and impaired the ability of both age groups of pups to autoresuscitate during repeated exposure to hypoxia (5–6 days tolerated – vehicle 17 ± 4 vs. DPCPX 10 ± 2 hypoxia exposures [P < 0.05]; 10–11 days tolerated – vehicle 10 ± 2 vs. DPCPX 7 ± 2 hypoxia exposures [P < 0.05]). Death in all pups resulted from the inability of gasping to restore cardiovascular function during hypoxia-induced apnea although the mechanism of cardiovascular dysfunction/failure was influenced and the occurrence hastened by DPCPX. Thus, our data provide evidence that adenosine acting via adenosine A1-receptors enhances the ability of rat pups to tolerate repeated exposure to severe hypoxia during early postnatal maturation.
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Affiliation(s)
- James E Fewell
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary Health Sciences Centre Alberta Children's Hospital Research Institute for Child and Maternal Health, Calgary, Alberta, Canada
| | - Rongzhi Lun
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary Health Sciences Centre Alberta Children's Hospital Research Institute for Child and Maternal Health, Calgary, Alberta, Canada
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Cummings KJ. Interaction of central and peripheral chemoreflexes in neonatal mice: evidence for hypo-addition. Respir Physiol Neurobiol 2014; 203:75-81. [PMID: 25192642 DOI: 10.1016/j.resp.2014.08.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
The potential for interaction between the peripheral (PCR) and central (CCR) chemoreflexes has not been studied in the neonatal period, when breathing is inherently unstable. Based on recent work in adult rodents, this study addresses the hypothesis that in neonatal mice there is a hypoadditive interaction between the chemoreflexes. To test this, a mask-pneumotach system was used to expose postnatal day (P) 11-12 mouse pups to square-wave hyperoxia (100% O2; n=8) or hypoxia (10% O2; n=11), administered in normocapnic conditions (inspired CO2 (FICO2)=0.001-0.005), or following an episode of re-breathing to increase FICO2 by 0.015-0.02. The immediate (i.e. PCR-mediated) responses of frequency (fB), tidal volume (VT) and ventilation (V˙E) to square-wave hyperoxia and hypoxia were assessed. When given in a normocapnic background, hyperoxia induced an immediate (within the first 20 breaths, or ∼6s) but transient fall in fB (-46±9breaths/min) and V˙E (-149±41μlmin(-1)g(-1)) (P<0.001 for both), with no effect on VT. In contrast, hyperoxia had no influence on breathing when it was administered following re-breathing. Similarly, the hypoxia-induced increase in fB was greater when applied under normocapnic conditions (50±8breaths/min) then when applied following re-breathing (21±5breaths/min) (P=0.02). These data demonstrate a hypo-additive interaction between the PCR and CCR with respect to the immediate frequency response to inhibition or excitation of the PCR. Hypoaddition of the chemoreflexes could cause or mitigate neonatal apnea, depending on the prevailing PCO2.
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Affiliation(s)
- Kevin J Cummings
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA.
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Zhang B, McDonald FB, Cummings KJ, Frappell PB, Wilson RJ. Novel method for conscious airway resistance and ventilation estimation in neonatal rodents using plethysmography and a mechanical lung. Respir Physiol Neurobiol 2014; 201:75-83. [DOI: 10.1016/j.resp.2014.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 07/04/2014] [Accepted: 07/04/2014] [Indexed: 11/29/2022]
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Yang HT, Cummings KJ. Brain stem serotonin protects blood pressure in neonatal rats exposed to episodic anoxia. J Appl Physiol (1985) 2013; 115:1733-41. [PMID: 24136109 DOI: 10.1152/japplphysiol.00970.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In neonatal rodents, a loss of brain stem serotonin [5-hydroxytryptamine (5-HT)] in utero or at birth compromises anoxia-induced gasping and the recovery of heart rate (HR) and breathing with reoxygenation (i.e., autoresuscitation). How mean arterial pressure (MAP) is influenced after an acute loss of brain stem 5-HT content is unknown. We hypothesized that a loss of 5-HT for ∼1 day would compromise MAP during episodic anoxia. We injected 6-fluorotryptophan (20 mg/kg ip) into rat pups (postnatal days 9-10 or 11-13, n = 22 treated, 24 control), causing a ∼70% loss of brain stem 5-HT. Pups were exposed to a maximum of 15 anoxic episodes, separated by 5 min of room air to allow autoresuscitation. In younger pups, we measured breathing frequency and tidal volume using "head-out" plethysmography and HR from the electrocardiogram. In older pups, we used whole body plethysmography to detect gasping, while monitoring MAP. Gasp latency and the time required for respiratory, HR, and MAP recovery following each episode were determined. Despite normal gasp latency, breathing frequency and a larger tidal volume (P < 0.001), 5-HT-deficient pups survived one-half the number of episodes as controls (P < 0.001). The anoxia-induced decrease in MAP experienced by 5-HT-deficient pups was double that of controls (P = 0.017), despite the same drop in HR (P = 0.48). MAP recovery was delayed ∼10 s by 5-HT deficiency (P = 0.001). Our data suggest a loss of brain stem 5-HT leads to a pronounced, premature loss of MAP in response to episodic anoxia. These data may help explain why some sudden infant death syndrome cases die from what appears to be cardiovascular collapse during apparent severe hypoxia.
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Affiliation(s)
- Hsiao T Yang
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
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Superchi P, Mazzoni C, Zanardelli P, Piancastelli C, Zambini EM, Beretti V, Sabbioni A. Effects of oral caffeine administration to sows with induced parturition on hypoxia in piglets. Livest Sci 2013. [DOI: 10.1016/j.livsci.2013.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Pohanka M, Dobes P. Caffeine inhibits acetylcholinesterase, but not butyrylcholinesterase. Int J Mol Sci 2013; 14:9873-82. [PMID: 23698772 PMCID: PMC3676818 DOI: 10.3390/ijms14059873] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 04/29/2013] [Accepted: 04/30/2013] [Indexed: 11/30/2022] Open
Abstract
Caffeine is an alkaloid with a stimulant effect in the body. It can interfere in transmissions based on acetylcholine, epinephrine, norepinephrine, serotonin, dopamine and glutamate. Clinical studies indicate that it can be involved in the slowing of Alzheimer disease pathology and some other effects. The effects are not well understood. In the present work, we focused on the question whether caffeine can inhibit acetylcholinesterase (AChE) and/or, butyrylcholinesterase (BChE), the two enzymes participating in cholinergic neurotransmission. A standard Ellman test with human AChE and BChE was done for altering concentrations of caffeine. The test was supported by an in silico examination as well. Donepezil and tacrine were used as standards. In compliance with Dixon’s plot, caffeine was proved to be a non-competitive inhibitor of AChE and BChE. However, inhibition of BChE was quite weak, as the inhibition constant, Ki, was 13.9 ± 7.4 mol/L. Inhibition of AChE was more relevant, as Ki was found to be 175 ± 9 μmol/L. The predicted free energy of binding was −6.7 kcal/mol. The proposed binding orientation of caffeine can interact with Trp86, and it can be stabilize by Tyr337 in comparison to the smaller Ala328 in the case of human BChE; thus, it can explain the lower binding affinity of caffeine for BChE with reference to AChE. The biological relevance of the findings is discussed.
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Affiliation(s)
- Miroslav Pohanka
- Faculty of Military Health Sciences, University of Defense, Trebesska 1575, 50001 Hradec Kralove, Czech Republic
- Author to whom correspondence should be addressed; E-Mail: ; Tel./Fax: +420-973-253-091
| | - Petr Dobes
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 65653 Brno, Czech Republic; E-Mail:
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Selected Literature Watch. JOURNAL OF CAFFEINE RESEARCH 2012. [DOI: 10.1089/jcr.2013.1225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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