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Selective glial, like selective neuronal, damage in the nucleus tractus solitarii disturbs cardiac and cardiovascular function
Abstracts / Autonomic Neuroscience: Basic and Clinical 163 (2011) 1–133
cells play a key role in pathophysiological processes or in the responses of NTS neurons to physiological stressors such as hypoxia is a matter of current investigation in our laboratory.
77
Financial support: NIH R01 HL088090.
doi:10.1016/j.autneu.2011.05.110 Keywords: Neuron-glia interactions, fluorocitrate, working heartbrainstem preparation, NTS
P.096 Purinergic modulation of preBötzinger Complex inspiratory rhythm generating networks
Financial support: CAPES, CNPQ e FAPESP.
doi:10.1016/j.autneu.2011.05.109
P.095 Selective glial, like selective neuronal, damage in the nucleus tractus solitarii disturbs cardiac and cardiovascular function W.T. Talman, D. Nitschke Dragon, S. Jones (Univ. of Iowa and VAMC — Neurology, United States), S.A. Moore (Univ. of Iowa and VAMC — Pathology, United States), L.-H. Lin (Univ. of Iowa and VAMC — Neurology, United States) We have previously reported that selective lesions of the nucleus tractus solitarii (NTS) lead to cardiac damage and arrhythmias like those seen in humans who have sustained central nervous system lesions. We found that selectively damaging NTS neurons that express NK1 receptors or those that express tyrosine hydroxylase (TH) leads to such cardiac dysfunction and associated lability of arterial pressure. In continuing efforts to better characterize cellular changes produced by introducing into the NTS conjugates containing the cytotoxin saporin (SAP), we have studied the effect of antidopamine-beta-hydroxylase (DBH)-saporin, stabilized substance P (SSP)-SAP, SAP (unconjugated), blank-SAP (non-targeted peptide conjugate), IgG-SAP (non-targeted immunoglobulin conjugate), and 6-hydoxydopamine (6-OHDA) injected into NTS both on the cellular markers [NMDAR1 (NMDA receptor subunit 1), GluR2 (AMPA receptor subunit 2), gamma-aminobutyric acid (GABA) receptor type a and b, neuronal nitirc oxide synthase (nNOS), TH, vesicular glutamate transporters (VGluTs), choline acetyl transferase (ChAT), glial fibrillary acidic protein (GFAP), connexin 43 (Cx43), DBH and protein gene product 9.5 (PGP 9.5)] and on cardiovascular and cardiac effects of the injected agents. We have found that each compound containing SAP (including blank-SAP, IgG-SAP, unconjugated SAP) led to loss of GFAP and Cx43 immunofluorescent labeling in the NTS as well as lability of arterial pressure, cardiac arrhythmias, and cardiac myocytolysis. Those outcomes occurred despite neuronal specificity for each of the conjugates. For example, anti-DBH-SAP led to a decrease in TH and DBH staining as well as a profound loss in GFAP and Cx43. In contrast, SSP-SAP led to loss of NK1 as well as GFAP, Cx43, and glutamate receptor markers but did not lead to loss of DBH or GABA. SSP-SAP also caused a loss in PGP9.5 which was not observed in all other reagents. SAP and blank-SAP, on the other hand, led to loss of GFAP and Cx43 while 6-OHDA led to loss of TH and DBH, increased GFAP and decreased Cx-43. In doses used 6-OHDA led to loss of TH and DBH but did not lead to either lability or cardiac events that were seen with each of the conjugates containing a SAP moiety. These data suggest that select neuronal damage or select glial damage in NTS may lead to artered regulation of blood pressure with consequent lability of blood pressure and cardiac damage.
Keywords: glia, neuron, nucleus tractus solitarii, baroreflex, arrhythmia, lability, toxin, saporin
J.D. Zwicker, S. Pagliardini (University of Alberta — Physiology, Canada), S. Kasparov (University of Bristol, UK — Physiology, United Kingdom), A.V. Gourine (University College London, United Kingdom), G.D. Funk (University of Alberta — Physiology, Canada) ATP actions on central inspiratory networks are determined by a 3-part signaling system comprising: i) the excitatory actions of ATP at P2 receptors (Rs) ii) ectonucleotidases that degrade ATP into adenosine (ADO), and iii) the inhibitory actions of ADO at P1Rs. During hypoxia, an initial increase in ventilation is followed by a secondary depression that is life threatening in premature infants. The release of ATP in respiratory networks, including the preBötzinger Complex (preBötC, important site of inspiratory rhythm generation) attenuates this secondary ventilatory depression. However, subsequent degradation of ATP to ADO may exacerbate the depression. In neonatal rats in vitro, ATP excites preBötC networks via a P2Y1R mechanism that involves both neurons and glia. Neither the enzymes responsible for ATP degradation, nor the effects of its metabolite, ADO, on preBötC networks are known. To further explore the significance of this 3-part signaling system for preBötC networks in rodents, P2 and P1R agonists/antagonists were injected into the preBötC of inspiratory rhythm-generating, medullary slices from mice and rats. P2Y1R activation caused 3-fold increase in frequency in mice and rats. Unlike rats, however, ATP only evoked a frequency increase in mice if A1 ADO Rs were blocked. Consistent with this, ADO inhibited preBötC frequency in mice but not rats. Real time PCR of preBötC mRNA revealed that TNAP (degrades ATP to ADO) is the main ectonucleotidase in mice while NTPDase2 (degrades ATP to ADP, a P2Y1R agonist). Data indicate that ATP effects on preBötC networks are determined by a delicate balance between P2 and P1R actions. In mouse, the balance favors inhibition, providing a valuable model to explore how purinergic signaling can be manipulated to counteract respiratory instabilities as seen in apnea of prematurity. We are now testing the significance of this ATP-ADO interaction in the mature preBötC. Keywords: purinergic, prebötzinger Complex, ectonucleotidase, ATP, adenosine Financial support: CIHR, WCHRI, AHFMR.
doi:10.1016/j.autneu.2011.05.111
Autonomic Dysfunction in Obesity & Hypertension P.097 Hyperphagia and obesity in mice with genetic ablation of gastrointestinal brain-derived neurotrophic factor E.A. Fox, J.E. Biddinger (Purdue University — Psychological Sciences, United States), K.R. Jones (University of Colorado, Boulder — Molecular, Cellular & Developmental Biology, United States), J. McAdams, A. Worman (Purdue University — Psychological Sciences, United States)
cells play a key role in pathophysiological processes or in the responses of NTS neurons to physiological stressors such as hypoxia is a matter of current investigation in our laboratory.
77
Financial support: NIH R01 HL088090.
doi:10.1016/j.autneu.2011.05.110 Keywords: Neuron-glia interactions, fluorocitrate, working heartbrainstem preparation, NTS
P.096 Purinergic modulation of preBötzinger Complex inspiratory rhythm generating networks
Financial support: CAPES, CNPQ e FAPESP.
doi:10.1016/j.autneu.2011.05.109
P.095 Selective glial, like selective neuronal, damage in the nucleus tractus solitarii disturbs cardiac and cardiovascular function W.T. Talman, D. Nitschke Dragon, S. Jones (Univ. of Iowa and VAMC — Neurology, United States), S.A. Moore (Univ. of Iowa and VAMC — Pathology, United States), L.-H. Lin (Univ. of Iowa and VAMC — Neurology, United States) We have previously reported that selective lesions of the nucleus tractus solitarii (NTS) lead to cardiac damage and arrhythmias like those seen in humans who have sustained central nervous system lesions. We found that selectively damaging NTS neurons that express NK1 receptors or those that express tyrosine hydroxylase (TH) leads to such cardiac dysfunction and associated lability of arterial pressure. In continuing efforts to better characterize cellular changes produced by introducing into the NTS conjugates containing the cytotoxin saporin (SAP), we have studied the effect of antidopamine-beta-hydroxylase (DBH)-saporin, stabilized substance P (SSP)-SAP, SAP (unconjugated), blank-SAP (non-targeted peptide conjugate), IgG-SAP (non-targeted immunoglobulin conjugate), and 6-hydoxydopamine (6-OHDA) injected into NTS both on the cellular markers [NMDAR1 (NMDA receptor subunit 1), GluR2 (AMPA receptor subunit 2), gamma-aminobutyric acid (GABA) receptor type a and b, neuronal nitirc oxide synthase (nNOS), TH, vesicular glutamate transporters (VGluTs), choline acetyl transferase (ChAT), glial fibrillary acidic protein (GFAP), connexin 43 (Cx43), DBH and protein gene product 9.5 (PGP 9.5)] and on cardiovascular and cardiac effects of the injected agents. We have found that each compound containing SAP (including blank-SAP, IgG-SAP, unconjugated SAP) led to loss of GFAP and Cx43 immunofluorescent labeling in the NTS as well as lability of arterial pressure, cardiac arrhythmias, and cardiac myocytolysis. Those outcomes occurred despite neuronal specificity for each of the conjugates. For example, anti-DBH-SAP led to a decrease in TH and DBH staining as well as a profound loss in GFAP and Cx43. In contrast, SSP-SAP led to loss of NK1 as well as GFAP, Cx43, and glutamate receptor markers but did not lead to loss of DBH or GABA. SSP-SAP also caused a loss in PGP9.5 which was not observed in all other reagents. SAP and blank-SAP, on the other hand, led to loss of GFAP and Cx43 while 6-OHDA led to loss of TH and DBH, increased GFAP and decreased Cx-43. In doses used 6-OHDA led to loss of TH and DBH but did not lead to either lability or cardiac events that were seen with each of the conjugates containing a SAP moiety. These data suggest that select neuronal damage or select glial damage in NTS may lead to artered regulation of blood pressure with consequent lability of blood pressure and cardiac damage.
Keywords: glia, neuron, nucleus tractus solitarii, baroreflex, arrhythmia, lability, toxin, saporin
J.D. Zwicker, S. Pagliardini (University of Alberta — Physiology, Canada), S. Kasparov (University of Bristol, UK — Physiology, United Kingdom), A.V. Gourine (University College London, United Kingdom), G.D. Funk (University of Alberta — Physiology, Canada) ATP actions on central inspiratory networks are determined by a 3-part signaling system comprising: i) the excitatory actions of ATP at P2 receptors (Rs) ii) ectonucleotidases that degrade ATP into adenosine (ADO), and iii) the inhibitory actions of ADO at P1Rs. During hypoxia, an initial increase in ventilation is followed by a secondary depression that is life threatening in premature infants. The release of ATP in respiratory networks, including the preBötzinger Complex (preBötC, important site of inspiratory rhythm generation) attenuates this secondary ventilatory depression. However, subsequent degradation of ATP to ADO may exacerbate the depression. In neonatal rats in vitro, ATP excites preBötC networks via a P2Y1R mechanism that involves both neurons and glia. Neither the enzymes responsible for ATP degradation, nor the effects of its metabolite, ADO, on preBötC networks are known. To further explore the significance of this 3-part signaling system for preBötC networks in rodents, P2 and P1R agonists/antagonists were injected into the preBötC of inspiratory rhythm-generating, medullary slices from mice and rats. P2Y1R activation caused 3-fold increase in frequency in mice and rats. Unlike rats, however, ATP only evoked a frequency increase in mice if A1 ADO Rs were blocked. Consistent with this, ADO inhibited preBötC frequency in mice but not rats. Real time PCR of preBötC mRNA revealed that TNAP (degrades ATP to ADO) is the main ectonucleotidase in mice while NTPDase2 (degrades ATP to ADP, a P2Y1R agonist). Data indicate that ATP effects on preBötC networks are determined by a delicate balance between P2 and P1R actions. In mouse, the balance favors inhibition, providing a valuable model to explore how purinergic signaling can be manipulated to counteract respiratory instabilities as seen in apnea of prematurity. We are now testing the significance of this ATP-ADO interaction in the mature preBötC. Keywords: purinergic, prebötzinger Complex, ectonucleotidase, ATP, adenosine Financial support: CIHR, WCHRI, AHFMR.
doi:10.1016/j.autneu.2011.05.111
Autonomic Dysfunction in Obesity & Hypertension P.097 Hyperphagia and obesity in mice with genetic ablation of gastrointestinal brain-derived neurotrophic factor E.A. Fox, J.E. Biddinger (Purdue University — Psychological Sciences, United States), K.R. Jones (University of Colorado, Boulder — Molecular, Cellular & Developmental Biology, United States), J. McAdams, A. Worman (Purdue University — Psychological Sciences, United States)