Aromaticl-amino acid decar☐ylase in the rat brain: Immunocytochemical localization in neurons of the brain stem

ABSTRACT The pseudorabies virus (PRV) gE gene encodes a multifunctional membrane protein found in infected cell membranes and in the virion envelope. Deletion of the gE gene results in marked attenuation of the virus in almost every animal species tested that is permissive for PRV. A common inference is that gE mutants are less virulent because they have reduced ability to spread from cell to cell; e.g., gE mutants infect fewer cells and, accordingly, animals live longer. In this report, we demonstrate that this inference does not hold in a rat experimental model for virus invasion of the brain. We find that animals infected with gE mutants live longer despite extensive retrograde, transneuronal spread of virus in the rat brain. In this model of brain infection, virus is injected into the stomach musculature and virions spread to the brain in long axons of brain stem neurons that give rise to the tenth cranial nerve (the vagus). The infection then spreads from neuron to neuron in well-defined, and physically separated, areas of the brain involved in autonomic regulation of the viscera. We examined the progression of infection of five PRV strains in this circuitry: the wild-type PRV-Becker strain, the attenuated PRV-Bartha vaccine strain, and three gE mutants isogenic with the PRV-Becker strain. By 60 to 67 h after infection, all PRV-Becker-infected animals were dead. Analysis of Becker-infected rats killed prior to virus-induced death demonstrated that the virus had established an infection only in the primary vagal neurons connected directly to the stomach and synaptically linked neurons in the immediate vicinity of the caudal brain stem. There was little spread to other neurons in the vagus circuitry. In contrast, rats infected with PRV-Bartha or PRV-Becker gE mutants survived to at least 96 h and exhibited few overt signs of disease. Despite this long survival and the lack of symptoms, brains of animals sacrificed at this time revealed extensive transsynaptic infection not only of the brain stem but also of areas of the forebrain synaptically linked to neurons in the brain stem. This finding provides evidence that the gE protein plays a role in promoting symptoms of infection and death in animals that is independent of neuron-to-neuron spread during brain infection. When this early virulence function is not active, animals live longer, resulting in more extensive spread of virus in the brain.

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Intermittent hypoxia activates peptidylglycine α-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing

Journal of Applied Physiology ◽

10.1152/japplphysiol.90702.2008 ◽

2009 ◽

Vol 106 (1) ◽

pp. 12-19 ◽

Cited By ~ 26

Author(s):

Suresh D. Sharma ◽

Gayatri Raghuraman ◽

Myeong-Seon Lee ◽

Nanduri R. Prabhakar ◽

Ganesh K. Kumar

Keyword(s):

Reactive Oxygen Species ◽

Substance P ◽

Neuropeptide Y ◽

Brain Stem ◽

Rat Brain ◽

Intermittent Hypoxia ◽

Reactive Oxygen ◽

Proteolytic Processing ◽

Oxygen Species ◽

The Brain

Intermittent hypoxia (IH) associated with sleep apneas leads to cardiorespiratory abnormalities that may involve altered neuropeptide signaling. The effects of IH on neuropeptide synthesis have not been investigated. Peptidylglycine α-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the α-amidation of neuropeptides, which confers biological activity to a large number of neuropeptides. PAM consists of O2-sensitive peptidylglycine α-hydroxylating monooxygenase (PHM) and peptidyl-α-hydroxyglycine α-amidating lyase (PAL) activities. Here, we examined whether IH alters neuropeptide synthesis by affecting PAM activity and, if so, by what mechanisms. Experiments were performed on the brain stem of adult male rats exposed to IH (5% O2for 15 s followed by 21% O2for 5 min; 8 h/day for up to 10 days) or continuous hypoxia (0.4 atm for 10 days). Analysis of brain stem extracts showed that IH, but not continuous hypoxia, increased PHM, but not PAL, activity of PAM and that the increase of PHM activity was associated with a concomitant elevation in the levels of α-amidated forms of substance P and neuropeptide Y. IH increased the relative abundance of 42- and 35-kDa forms of PHM (∼1.6- and 2.7-fold, respectively), suggesting enhanced proteolytic processing of PHM, which appears to be mediated by an IH-induced increase of endoprotease activity. Kinetic analysis showed that IH increases Vmaxbut has no effect on Km. IH increased generation of reactive oxygen species in the brain stem, and systemic administration of antioxidant prevented IH-evoked increases of PHM activity, proteolytic processing of PHM, endoprotease activity, and elevations in substance P and neuropeptide Y amide levels. Taken together, these results demonstrate that IH activates PHM in rat brain stem via reactive oxygen species-dependent posttranslational proteolytic processing and further suggest that PAM activation may contribute to IH-mediated peptidergic neurotransmission in rat brain stem.

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d-Amino-acid oxidase is confined to the lower brain stem and cerebellum in rat brain: regional differentiation of astrocytes

Brain Research ◽

10.1016/0006-8993(94)90240-2 ◽

1994 ◽

Vol 652 (2) ◽

pp. 297-303 ◽

Cited By ~ 127

Author(s):

Kihachiro Horiike ◽

Hiromasa Tojo ◽

Ryohachi Arai ◽

Mitsuhiro Nozaki ◽

Toshihiro Maeda

Keyword(s):

Amino Acid ◽

Brain Stem ◽

Rat Brain ◽

Regional Differentiation ◽

Acid Oxidase ◽

Amino Acid Oxidase ◽

Lower Brain Stem

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Permeability of the microcirculation in area postrema of rat

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100103802 ◽

1988 ◽

Vol 46 ◽

pp. 348-349

Author(s):

Shams M. Ghoneim ◽

Frank M. Faraci ◽

Gary L. Baumbach

Keyword(s):

Brain Stem ◽

Area Postrema ◽

Upper Body ◽

Sprague Dawley ◽

Sodium Cacodylate ◽

Acute Hypertension ◽

Sprague Dawley Rats ◽

Ultrastructural Characteristics ◽

The Brain ◽

Adjacent Brain

The area postrema is a circumventricular organ in the brain stem and is one of the regions in the brain that lacks a fully functional blood-brain barrier. Recently, we found that disruption of the microcirculation during acute hypertension is greater in area postrema than in the adjacent brain stem. In contrast, hyperosmolar disruption of the microcirculation is greater in brain stem. The objective of this study was to compare ultrastructural characteristics of the microcirculation in area postrema and adjacent brain stem.We studied 5 Sprague-Dawley rats. Horseradish peroxidase was injected intravenously and allowed to circulate for 1, 5 or 15 minutes. Following perfusion of the upper body with 2.25% glutaraldehyde in 0.1 M sodium cacodylate, the brain stem was removed, embedded in agar, and chopped into 50-70 μm sections with a TC-Sorvall tissue chopper. Sections of brain stem were incubated for 1 hour in a solution of 3,3' diaminobenzidine tetrahydrochloride (0.05%) in 0.05M Tris buffer with 1% H2O2.

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Immunoelectron microscope detection of C-type natriuretic peptide in normal human atrial tissue

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147776 ◽

1993 ◽

Vol 51 ◽

pp. 388-389

Author(s):

Chi-Ming Wei ◽

Margaret Hukee ◽

Christopher G.A. McGregor ◽

John C. Burnett

Keyword(s):

Amino Acid ◽

Natriuretic Peptide ◽

Vascular Tone ◽

Cardiac Tissue ◽

Ring Structure ◽

Terminal Amino Acid ◽

Amino Acid Peptide ◽

Normal Human ◽

Terminal Amino ◽

The Brain

C-type natriuretic peptide (CNP) is a newly identified peptide that is structurally related to atrial (ANP) and brain natriuretic peptide (BNP). CNP exists as a 22-amino acid peptide and like ANP and BNP has a 17-amino acid ring formed by a disulfide bond. Unlike these two previously identified cardiac peptides, CNP lacks the COOH-terminal amino acid extension from the ring structure. ANP, BNP and CNP decrease cardiac preload, but unlike ANP and BNP, CNP is not natriuretic. While ANP and BNP have been localized to the heart, recent investigations have failed to detect CNP mRNA in the myocardium although small concentrations of CNP are detectable in the porcine myocardium. While originally localized to the brain, recent investigations have localized CNP to endothelial cells consistent with a paracrine role for CNP in the control of vascular tone. While CNP has been detected in cardiac tissue by radioimmunoassay, no studies have demonstrated CNP localization in normal human heart by immunoelectron microscopy.

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Surgical Approaches to the Brain Stem

Neurosurgery Clinics of North America ◽

10.1016/s1042-3680(18)30570-9 ◽

1993 ◽

Vol 4 (3) ◽

pp. 457-468 ◽

Cited By ~ 16

Author(s):

Dennis Y. Wen ◽

Roberto C. Heros

Keyword(s):

Brain Stem ◽

Surgical Approaches ◽

The Brain

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