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Previous issue date: 2017 / Existem evid?ncias que a estimula??o colin?rgica central aumenta a dissipa??o de calor em
ratos normotensos como consequ?ncia de altera??es cardiovasculares via modula??o da
atividade barorreflexa. No entanto, n?o h? dados publicados sobre o envolvimento do sistema
colin?rgico central nestas respostas em modelo experimental que apresenta altera??o da
sensibilidade dos barorreceptores e d?ficit termorregulat?rio. Assim, o objetivo do presente
estudo foi verificar o envolvimento do sistema colin?rgico central na modula??o das repostas
cardiovasculares e termorregulat?rias durante o repouso e exerc?cio f?sico em ratos
espontaneamente hipertensos (SHR). Ratos Wistar machos (n = 33) e SHR (n = 33) foram
implantados com uma c?nula intracerebroventricular (icv) para inje??es de 2 ?L de
fisostigmina (fis) ou solu??o salina (sal). Temperaturas da cauda (Tcauda) e corporal interna
(Tint), press?o arterial sist?lica (PAS), frequ?ncia card?aca (FC) e taxa metab?lica foram
registradas durante os 60 minutos em que os ratos permaneceram em repouso, bem como
durante o exerc?cio f?sico at? a fadiga ap?s inje??es icv randomizadas. Na situa??o repouso, o
tratamento com fis iniciou uma sucess?o de respostas cardiovasculares e termorregulat?rias
que resultaram em aumento da PAS, redu??o da FC e aumento de Tcauda nos grupos Wistar e
SHR. A magnitude da ativa??o desses mecanismos foi mais intensa no SHR, afetando a Tint e
melhorando a dissipa??o de calor. Durante o exerc?cio f?sico, o tratamento com fis foi capaz
de modular as repostas cardiovasculares promovendo aumento significativo da PAS, seguido
de bradicardia reflexa em ratos SHR e Wistar. Estas respostas foram mais intensas nos ratos
Wistar. N?o houve diferen?a significativa para a Tcauda e Tint no grupo SHR fis em rela??o ao
grupo sal. Entretanto, fis impactou positivamente no desempenho f?sico. Em conjunto, esses
resultados fornecem evid?ncias que, durante a situa??o de repouso, a estimula??o colin?rgica
central modula as repostas termorregulat?rias por meio de mudan?as no sistema
cardiovascular de ratos Wistar e SHR, sendo que essas respostas s?o mais acentuadas em ratos
SHR impactando na dissipa??o de calor. Durante o exerc?cio f?sico, a administra??o central de
fis promove altera??es no sistema cardiovascular de ratos normotensos e hipertensos. Apesar
dessas altera??es n?o terem sido suficientes para ajustar as respostas termorregulat?rias em
ratos SHR, impactaram positivamente no desempenho f?sico. / Tese (Doutorado) ? Programa Multic?ntrico de P?s-Gradua??o em Ci?ncias Fisiol?gicas, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / There is evidence that central cholinergic stimulation increases heat dissipation in
normotensive rats through changes on the cardiovascular system via modulation of
baroreceptors function. However, there is no published data regarding the involvement of the
central cholinergic system in cardiovascular and thermoregulatory responses in spontaneously
hypertensive rats (SHR), which are animals that possess altered baroreceptor sensitivity and
thermoregulatory deficit. Therefore, the aim of this study was to verify the involvement of the
central cholinergic system in cardiovascular and thermoregulatory adjustments in SHR. Male
Wistar (n = 33) and SHR (n = 33) rats were implanted with an intracerebroventricular (icv)
cannula for injections of 2 ?L of physostigmine (phy) or saline (sal) solution. Tail (Ttail) and
internal body temperatures (Tint), systolic arterial pressure (SAP), heart rate (HR) and
metabolic rate were registered during 60 minutes while the animals remained at rest and
during exercise until fatigue after randomly receiving the injections. Phy treatment started a
succession of cardiovascular and thermoregulatory responses that resulted in increased SAP,
reduced HR and increased Ttail in both Wistar and SHR groups. The magnitude of the
activation of these mechanisms seems to be more intense in SHR, even affecting the Tint, and
improve heat dissipation. During physical exercise, the phy treatment was able to modulate
the cardiovascular responses promoting a significant increase of SAP, followed by reflex
bradycardia in SHR and Wistar rats. These responses were more intense in Wistar rats. There
was no significant difference for Ttail and Tint in the SHR group, however, phy positively
impacted the physical performance. Taken together, these results provide evidence that at rest
the central cholinergic stimulation modulates thermoregulatory responses through changes in
the cardiovascular system of Wistar and SHR rats, and SHR rats presented greater
cardiovascular and thermoregulatory responses than normotensive rats after central
cholinergic stimulation. During physical exercise the central administration of phy promotes
adjustments in the cardiovascular system of normotensive and hypertensive rats. Although
these adjustments were not sufficient to pair the thermoregulatory responses in SHR rats, they
had a positive impact on physical performance.
| Identifer | oai:union.ndltd.org:IBICT/oai:acervo.ufvjm.edu.br/jspui:1/1745 |
| Date | 15 December 2017 |
| Creators | Fonseca, Sueli Ferreira da |
| Contributors | Lacerda, Ana Cristina Rodrigues, Peixoto, Marco Fabricio Dias, Soares, Danusa Dias, Wanner, Samuel Penna, Villela, Daniel Campos, Coimbra, C?ndido Celso, Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), Lacerda, Ana Cristina Rodrigues |
| Publisher | UFVJM |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFVJM, instname:Universidade Federal dos Vales do Jequitinhonha e Mucuri, instacron:UFVJM |
| Rights | A concess?o da licen?a deste item refere-se ao ? termo de autoriza??o impresso assinado pelo autor, assim como na licen?a Creative Commons, com as seguintes condi??es: Na qualidade de titular dos direitos de autor da publica??o, autorizo a Universidade Federal dos Vales do Jequitinhonha e Mucuri e o IBICT a disponibilizar por meio de seus reposit?rios, sem ressarcimento dos direitos autorais, de acordo com a Lei n? 9610/98, o texto integral da obra disponibilizada, conforme permiss?es assinaladas, para fins de leitura, impress?o e/ou download, a t?tulo de divulga??o da produ??o cient?fica brasileira, e preserva??o, a partir desta data., info:eu-repo/semantics/openAccess |
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