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Doctoral Thesis
DOI
10.11606/T.42.2014.tde-19022015-143700
Document
Author
Full name
Hildebrando Candido Ferreira Neto
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2014
Supervisor
Committee
Antunes, Vagner Roberto (President)
Abdulkader, Fernando Rodrigues de Moraes
Machado, Benedito Honório
Moreira, Thiago dos Santos
Ulrich, Alexander Henning
Title in Portuguese
Estudo da interação entre ATP e glutamato em neurônios do núcleo paraventricular do hipotálamo e sua relação com a resposta simpatoexcitatória induzida por alterações na osmolaridade.
Keywords in Portuguese
AMPA
Atividade simpática
ATP
Hiperosmolaridade
L-Glutamato
Núcleo paraventricular do hipotálamo
Receptores purinérgicos
RVLM
Abstract in Portuguese
Neste trabalho investigamos a interação entre ATP-glutamato na modulação de potenciais de ação e atividade sináptica de neurônios PVN-RVLM, além de avaliar se esta interação induziria mudanças na atividade simpática lombar (ANSL) por estímulo osmótico. Utilizamos de técnicas de imunohistoquímica, whole-cell patch clamp e registro eletroneurográfico. Observou-se que o ATP aumenta a frequência de potenciais de ação em neurônios PVN-RVLM, efeito bloqueado por acido quinurênico (KYN) e PPADS. A injeção de ATP no PVN aumenta a ANSL (25 nmol: 72%), um efeito atenuado por PPADS e/ou KYN, e também por CNQX. O ATP não afeta a função sináptica, mas aumenta correntes glutamatérgicas induzidas por aplicação AMPA em 52%, a qual foi bloqueada por PPADS ou por quelação de Ca2+ intracelular. Além disso, o estímulo osmótico ativa neurônios do PVN que expressam receptores P2X2 e potencia as correntes mediadas por AMPA (53%), um efeito bloqueado por PPADS. Finalmente, demonstrou-se que receptores P2 no PVN são importantes na simpatoexcitação induzida por estímulo osmótico agudo.
Title in English
Study of the interaction between ATP and glutamate in neurons of the paraventricular nucleus of the hypothalamus and its relationship with the sympathoexcitatory response induced by changes in osmolarity.
Keywords in English
AMPA
ATP
Hyperosmolarity
L-Glutamate
Paraventricular nucleus of the hypothalamus
Purinergic receptors
RVLM
Sympathetic activity
Abstract in English
In the present study we investigate the interaction of ATP-glutamate on the firing activity and synaptic function in PVN-RVLM neurons, besides whether that interaction would be translated in changes on sympathetic nerve activity (SNA) induced by osmotic stimulus. Immunohistochemistry, whole-cell patch clamp and electroneurography technical approaches were used. Our data have shown that ATP increases firing rate of PVN-RVLM neurons, an effect blocked by kynurenic acid (KYN) or PPADS. ATP injection into the PVN enhanced SNA (72%), which was attenuated by PPADS and/or KYN, or CNQX. ATP did not affect synaptic function but, glutamatergic currents evoked by AMPA application were augmented with ATP (AMPA area: 52%), blocked by PPADS and chelation of intracellular Ca2+. In addition, we observed that acute osmotic stimulus activates P2X2 expressing neurons in the PVN. Moreover, an osmotic challenge potentiated AMPA responses (53%), an effect blocked by PPADS. Finally, we demonstrated that P2 receptors in the PVN are important for osmotically-driven sympathoexcitation.
 
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Release Date
2017-02-19
Publishing Date
2015-02-20
 
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