O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal
Autor(a) principal: | |
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Data de Publicação: | 2019 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFG |
Texto Completo: | http://repositorio.bc.ufg.br/tede/handle/tede/9791 |
Resumo: | High sodium intake can affect the excitability of neurons in regions responsible for the control of sympathetic nervous activity. It is known that the neuronal activity of the hypothalamus paraventricular nucleus (PVN) is increased in several models of sodium-sensitive arterial hypertension (SSH). Diseases that develop in adulthood are related to certain exposures suffered by the individual during the early stages of life. However, the literature point out differences between males and females in the expression of hypertension in both animal and human models, and in females, estrogen sometimes has a cardioprotective effect. In the present study, we investigated whether changes in diet during the postnatal phases contribute to central alterations in the control of renal sympathetic tone in males and females, and whether they persist in adulthood. More specifically, we evaluated the contribution of the PVN in the control of cardiovascular parameters and sympathetic nervous activity (SNA) after treatment with a sodium-rich diet for 30 days in adult rats and rats. Twenty one days old wistar male and female rats were divided into two groups: control group, composed of males (MCTRL) and females (FCTRL), maintained with water; and experimental group, composed of males (MEXP) and females (FEXP), maintained with hypertonic solution of 0.3 M NaCl. Animals of all groups received chow and hypertonic solution or water ad libitum for 30 days. After treatment, the animals of all groups were maintained with water and chow for 15 days (recovery period). Daily food and fluid (0.3 M NaCl or water) intake and body weight were monitored during the treatment and recovery periods. At the end of treatment, the treated male rats were found to have lower body weight compared to controls (MEXP (n = 9): 115.3 ± 4.7 g vs. MCTRL (n = 9): 168.0 ± 8.0 g, p <0.05). However, this difference was not observed between the experimental and control female groups (FEXP (n = 8): 119.5 ± 5.3 g vs. FCTRL (n = 8): 134.1 ± 5.2 g). We also observed that the experimental animals ingested a greater amount of fluid per gram of body weight (bw) than control animals MEXP (n=9): 0.717 ± 0.120 mL/g/bw vs. MCTRL (n=9): 0.209; FEXP (n=8): 0.576 ± 0.060 mL/g/bw vs. FCTRL (n=8): 0.251 ± 0.011 mL/g/bw, p < 0.05) and we observed a decrease in the excreted volume (Vexc) in experimental females compared to the ingested volume (Ving) (FEXP (n=8): Ving 89.6 ± 5.6 mL vs. Vexc 56.8 ± 5.2 mL, p < 0.05). In the recovery period there was no difference in daily water intake between groups (MEXP (n=9): 0.203 ± 0.008 mL/g/bw vs. MCTRL (n=9): 0,171 ± 0.005 mL/g/bw; FEXP (n=8): 0,229 ± 0,013 mL/g/bw vs. FCTRL (n=8): 0.187 ± 0,010 mL/g/bw). In another set of experiments, we evaluated the participation of the PVN in the maintenance of sympathetic tonus after treatment with a high sodium diet for 30 days. Bilateral nanoinjections of 50 nL of muscimol (GABAA agonist, 4 mM) were performed in the PVN in experimental and control animals during recording of mean arterial pressure (MAP), heart rate (HR) and renal SNA (RSNA). It is noteworthy that in the females these experiments were performed in the diestrus of the estrous cycle. In the anaesthetized experiments, the males of the treated group showed higher values of baseline MAP compared to both control male group and to female groups (PAM: MEXP (n=6): 108.2 ± 2.9 mmHg vs. MCTRL (n=6): 92 ± 5.4 mmHg vs. FEXP (n=6): 102.7 ± 4.4 mmHg vs. FCTRL (n=6): 90.8 ± 1.8 mmHg, p<0.05). Inhibition of the PVN promoted a reduction on MAP of experimental groups when compared to control groups: (Δ MAP: MEXP (n=6): -14.9 ± 1.5 mmHg vs. MCTRL (n=6): -7.2 ± 0.7 mmHg vs. FEXP (n=6): -12.9 ± 1.7 mmHg vs. FCTRL (n=6): -4.8 ± 0.6 mmHg, p <0.05). On the other hand, no differences were observed in the HR responses of the evaluated groups (Δ HR: MEXP (n=6): -35.8 ± 6.6 bpm vs. MCTRL (n=6): -21.6 ± 2.9 bpm vs. FEXP (n=6): -27.8 ± 3.5 bpm vs. FCTRL (n=6): -31.0 ± 4.4 bpm). In addition, acute inhibition of PVN promoted renal sympathoinhibition in experimental animals compared to controls (Δ % ANSR: MEXP (n=6): -17.3 ± 1.5% vs. MCTRL (n=6): -6.8 ± 1.0% vs. FEXP (n=6): -18.1 ± 0.5% vs. FCTRL (n=6): -3.0 ± 0.6%, p <0.05). The results demonstrated in the present study showed that the hypersodiuc diet during the early stages of life altered baseline MAP of experimental males. Additionally, we observed that the acute inhibition of PVN promoted cardiovascular and sympathetic changes in rats treated with a high sodium diet in comparison to the control group. Taken together, the observed results add new information to the literature and suggest that cardiovascular and sympathetic control regions, such as the PVN, may be more involved in the tonic modulation of blood pressure and RSNA in response to sodium overload in the postnatal phase of normotensive rats. Finally, our study points to the possibility that estrogen may have helped decrease the high blood pressure promoted by prolonged increase in sodium intake, but it was not enough to prevent the increase in the modulation of the sympathetic tone exerted by the PVN. However, future studies are needed to investigate pathways and mechanisms involved in these responses. |
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Pedrino, Gustavo Rodrigueshttp://lattes.cnpq.br/1155446449250341Mourão, Aline Andradehttp://lattes.cnpq.br/1596884578398481Ferreira-Neto, Marcos LuizMendes, Elizabeth PereiraPedrino, Gustavo Rodrigueshttp://lattes.cnpq.br/6583838264355921Almeida, Melissa Tavares2019-07-04T15:02:00Z2019-06-28ALMEIDA, M. T. O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal. 2019. 73 f. Dissertação (Mestrado Ciências Fisiológicas) - Universidade Federal de Goiás, Goiânia, 2019.http://repositorio.bc.ufg.br/tede/handle/tede/9791ark:/38995/0013000004mb0High sodium intake can affect the excitability of neurons in regions responsible for the control of sympathetic nervous activity. It is known that the neuronal activity of the hypothalamus paraventricular nucleus (PVN) is increased in several models of sodium-sensitive arterial hypertension (SSH). Diseases that develop in adulthood are related to certain exposures suffered by the individual during the early stages of life. However, the literature point out differences between males and females in the expression of hypertension in both animal and human models, and in females, estrogen sometimes has a cardioprotective effect. In the present study, we investigated whether changes in diet during the postnatal phases contribute to central alterations in the control of renal sympathetic tone in males and females, and whether they persist in adulthood. More specifically, we evaluated the contribution of the PVN in the control of cardiovascular parameters and sympathetic nervous activity (SNA) after treatment with a sodium-rich diet for 30 days in adult rats and rats. Twenty one days old wistar male and female rats were divided into two groups: control group, composed of males (MCTRL) and females (FCTRL), maintained with water; and experimental group, composed of males (MEXP) and females (FEXP), maintained with hypertonic solution of 0.3 M NaCl. Animals of all groups received chow and hypertonic solution or water ad libitum for 30 days. After treatment, the animals of all groups were maintained with water and chow for 15 days (recovery period). Daily food and fluid (0.3 M NaCl or water) intake and body weight were monitored during the treatment and recovery periods. At the end of treatment, the treated male rats were found to have lower body weight compared to controls (MEXP (n = 9): 115.3 ± 4.7 g vs. MCTRL (n = 9): 168.0 ± 8.0 g, p <0.05). However, this difference was not observed between the experimental and control female groups (FEXP (n = 8): 119.5 ± 5.3 g vs. FCTRL (n = 8): 134.1 ± 5.2 g). We also observed that the experimental animals ingested a greater amount of fluid per gram of body weight (bw) than control animals MEXP (n=9): 0.717 ± 0.120 mL/g/bw vs. MCTRL (n=9): 0.209; FEXP (n=8): 0.576 ± 0.060 mL/g/bw vs. FCTRL (n=8): 0.251 ± 0.011 mL/g/bw, p < 0.05) and we observed a decrease in the excreted volume (Vexc) in experimental females compared to the ingested volume (Ving) (FEXP (n=8): Ving 89.6 ± 5.6 mL vs. Vexc 56.8 ± 5.2 mL, p < 0.05). In the recovery period there was no difference in daily water intake between groups (MEXP (n=9): 0.203 ± 0.008 mL/g/bw vs. MCTRL (n=9): 0,171 ± 0.005 mL/g/bw; FEXP (n=8): 0,229 ± 0,013 mL/g/bw vs. FCTRL (n=8): 0.187 ± 0,010 mL/g/bw). In another set of experiments, we evaluated the participation of the PVN in the maintenance of sympathetic tonus after treatment with a high sodium diet for 30 days. Bilateral nanoinjections of 50 nL of muscimol (GABAA agonist, 4 mM) were performed in the PVN in experimental and control animals during recording of mean arterial pressure (MAP), heart rate (HR) and renal SNA (RSNA). It is noteworthy that in the females these experiments were performed in the diestrus of the estrous cycle. In the anaesthetized experiments, the males of the treated group showed higher values of baseline MAP compared to both control male group and to female groups (PAM: MEXP (n=6): 108.2 ± 2.9 mmHg vs. MCTRL (n=6): 92 ± 5.4 mmHg vs. FEXP (n=6): 102.7 ± 4.4 mmHg vs. FCTRL (n=6): 90.8 ± 1.8 mmHg, p<0.05). Inhibition of the PVN promoted a reduction on MAP of experimental groups when compared to control groups: (Δ MAP: MEXP (n=6): -14.9 ± 1.5 mmHg vs. MCTRL (n=6): -7.2 ± 0.7 mmHg vs. FEXP (n=6): -12.9 ± 1.7 mmHg vs. FCTRL (n=6): -4.8 ± 0.6 mmHg, p <0.05). On the other hand, no differences were observed in the HR responses of the evaluated groups (Δ HR: MEXP (n=6): -35.8 ± 6.6 bpm vs. MCTRL (n=6): -21.6 ± 2.9 bpm vs. FEXP (n=6): -27.8 ± 3.5 bpm vs. FCTRL (n=6): -31.0 ± 4.4 bpm). In addition, acute inhibition of PVN promoted renal sympathoinhibition in experimental animals compared to controls (Δ % ANSR: MEXP (n=6): -17.3 ± 1.5% vs. MCTRL (n=6): -6.8 ± 1.0% vs. FEXP (n=6): -18.1 ± 0.5% vs. FCTRL (n=6): -3.0 ± 0.6%, p <0.05). The results demonstrated in the present study showed that the hypersodiuc diet during the early stages of life altered baseline MAP of experimental males. Additionally, we observed that the acute inhibition of PVN promoted cardiovascular and sympathetic changes in rats treated with a high sodium diet in comparison to the control group. Taken together, the observed results add new information to the literature and suggest that cardiovascular and sympathetic control regions, such as the PVN, may be more involved in the tonic modulation of blood pressure and RSNA in response to sodium overload in the postnatal phase of normotensive rats. Finally, our study points to the possibility that estrogen may have helped decrease the high blood pressure promoted by prolonged increase in sodium intake, but it was not enough to prevent the increase in the modulation of the sympathetic tone exerted by the PVN. However, future studies are needed to investigate pathways and mechanisms involved in these responses.O consumo elevado de sódio pode afetar a excitabilidade de neurônios de regiões responsáveis pelo controle da atividade nervosa simpática. Sabe-se que a atividade neuronal do núcleo paraventricular (PVN) do hipotálamo encontra-se aumentada em diversos modelos de hipertensão arterial sensível ao sódio (HSS). Doenças que se desenvolvem na fase adulta estão relacionadas a determinadas exposições sofridas pelo indivíduo durante as fases iniciais da vida. No entanto, a literatura aponta diferenças entre machos e fêmeas na expressão da hipertensão tanto em modelos animais quanto em humanos, sendo que em fêmeas, o estrógeno por vezes apresenta um efeito cardioprotetor. No presente estudo, investigamos se alterações na dieta durante as fases pós-natais contribuem para alterações centrais no controle do tônus simpático renal em machos e fêmeas e, se estas persistem na fase adulta. Mais especificamente, avaliamos a contribuição do PVN no controle dos parâmetros cardiovasculares e de atividade nervosa simpática (ANS) após o tratamento com dieta rica em sódio por 30 dias em ratos e ratas adultos. Foram utilizados ratos e ratas da linhagem Wistar com 21 dias divididos em dois grupos: grupo controle, composto por machos (MCTRL) e fêmeas (FCTRL), mantidos com água; e grupo experimental, composto por machos (MEXP) e fêmeas (FEXP), mantidos com solução hipertônica de NaCl 0,3 M. Os animais de todos os grupos receberam ração e a solução hipertônica ou água ad libitum por 30 dias. Após o tratamento, os animais de todos os grupos foram mantidos com água e ração por 15 dias (período de recuperação). A ingestão diária de fluido (NaCl 0,3M ou água), ração e o peso corporal foram acompanhados durante os períodos de tratamento e recuperação. Ao final do tratamento, observou-se que os ratos tratados possuíam menor peso corporal em relação aos controles (MEXP (n=9): 115,3 ± 4,7 g vs. MCTRL (n=9): 168,0 ± 8,0 g, p < 0,05). Entretanto, tal diferença não foi observada entre os grupos de fêmeas experimentais e controles (FEXP (n=8): 119,5 ± 5,3 g vs. FCTRL (n=8): 134,1 ± 5,2 g). Observamos também que os animais experimentais ingeriram maior quantidade de fluido por grama de peso corporal (pc) em relação aos animais controles (MEXP (n=9): 0,7 ± 0,12 mL/g/pc vs. MCTRL (n=9): 0,2 ± 0,001 mL/g/pc; FEXP (n=8): 0,57 ± 0,06 mL/g/pc vs. FCTRL (n=8): 0,251 ± 0,01 mL/g/pc, p < 0,05) e observamos uma diminuição do volume excretado (Vexc) nas fêmeas experimentais comparado ao volume ingerido (Ving) (FEXP (n=8): Ving 89,6 ± 5,6 mL vs. Vexc 56,8 ± 5,2mL, p < 0,05).No período de recuperação não houve diferença na ingestão diária de água entre os grupos (MEXP (n=9): 0,203 ± 0,008 mL/g/pc vs. MCTRL (n=9): 0,171 ± 0,005 mL/g/pc; FEXP (n=8): 0,229 ± 0,013 mL/g/pc vs. FCTRL (n=8): 0,187 ± 0,010 mL/g/pc). Em outra série de experimentos, avaliamos a participação do PVN, para a manutenção do tônus simpático após o tratamento com dieta rica em sódio por 30 dias. Nanoinjeções bilaterais de 50 nL de muscimol (agonista GABAA; 4mM) foram realizadas no PVN em animais dos grupos controle e experimental durante o registro de pressão arterial média (PAM), frequência cardíaca (FC) e ANS renal (ANSR). Vale ressaltar que nas fêmeas estes experimentos foram realizados no diestro do ciclo estral. Nos experimentos anestesiados, os machos do grupo tratado demonstraram valores elevados de PAM basal em relação tanto a seus pares do grupo controle, quanto aos grupos de fêmeas (PAM: MEXP (n=6): 108,2 ± 2,9 mmHg vs. MCTRL (n=6): 92 ± 5,4 mmHg vs. FEXP (n=6): 102,7 ± 4,4mmHg vs. FCTRL (n=6): 90,8 ± 1,8mmHg; p < 0,05). A inibição do PVN promoveu redução na PAM dos grupos experimentais quando comparados aos grupos controles: (Δ PAM: MEXP (n=6): -14,9 ± 1,5 mmHg vs. MCTRL (n=6): -7,2 ± 0,7 mmHg; FEXP (n=6): -12,9 ± 1,7 mmHg vs. FCTRL (n=6): -4,8 ± 0,6 mmHg p < 0,05). Por outro lado, não foram observadas diferenças nas respostas de FC dos grupos avaliados (Δ FC: MEXP (n=6): -35,8 ± 6,6 bpm vs. MCTRL (n=6): -21,6 ± 2,9 bpm; FEXP (n=6): -27,8 ± 3,5 bpm vs. FCTRL (n=6): -31,0 ± 4,4 bpm). Além disso, a inibição aguda do PVN promoveu simpatoinibição renal nos animais experimentais comparados aos controles (Δ %ANSR: MEXP (n=6): -17,3 ± 1,5 % vs. MCTRL (n=6): -6,8 ± 1,0 %; FEXP (n=6): -18,1 ± 0,5 %vs. FCTRL (n=6): -3,0 ± 0,6 %; p < 0,05). Os resultados demonstrados no presente estudo mostraram que a dieta hipersódica durante as fases iniciais da vida alterou a PAM basal dos machos experimentais. Adicionalmente, observamos que a inibição aguda do PVN promoveu alterações cardiovasculares e simpáticas nos ratos tratados com dieta rica em sódio em comparação ao grupo controle. Em conjunto, os resultados observados adicionam novas informações à literatura e sugerem que regiões de controle cardiovascular e simpático, como o PVN, podem estar mais envolvidas na modulação tônica da pressão arterial e ANSR, em resposta à sobrecarga de sódio na fase pós-natal de ratos normotensos. Por fim, nosso estudo aponta para a possibilidade de que o estrógeno tenha auxiliado na diminuição do efeito pressórico elevado promovido pelo aumento prolongado da ingestão de sódio, mas não foi suficiente para prevenir o aumento da modulação no tônus simpático exercido pelo PVN. No entanto, estudos futuros são necessários para investigar vias e mecanismos envolvidos nessas respostas.Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2019-07-04T15:00:08Z No. of bitstreams: 2 Dissertação - Melissa Tavares Almeida - 2019.pdf: 2768346 bytes, checksum: 73afd849006154880501378295d3f00a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2019-07-04T15:02:00Z (GMT) No. of bitstreams: 2 Dissertação - Melissa Tavares Almeida - 2019.pdf: 2768346 bytes, checksum: 73afd849006154880501378295d3f00a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Made available in DSpace on 2019-07-04T15:02:00Z (GMT). No. of bitstreams: 2 Dissertação - Melissa Tavares Almeida - 2019.pdf: 2768346 bytes, checksum: 73afd849006154880501378295d3f00a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2019-06-28Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEGapplication/pdfporUniversidade Federal de GoiásPrograma de Pós-graduação em Ciências Fisiológicas - Multicêntrico (ICB)UFGBrasilInstituto de Ciências Biológicas - ICB (RG)http://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/openAccessSobrecarga de sódioDoenças cardiovascularesAtividade nervosa simpática renalPressão arterialIngestão de sódioEstrógenoSodium overloadCardiovascular diseasesRenal sympathetic nervous activityBlood pressureSodium intakeEstrogenCIENCIAS BIOLOGICAS::FISIOLOGIAO envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natalInvolvement of the paraventricular nucleus of the hypothalamus in the maintenance of blood pressure and modulation of renal sympathetic tone of rats treated with in a sodium rich diet in the post natal phaseinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesis1337318928839825463600600600600-38727721178273734047737708247419018223-961409807440757778reponame:Repositório Institucional da UFGinstname:Universidade Federal de Goiás (UFG)instacron:UFGLICENSElicense.txtlicense.txttext/plain; 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dc.title.eng.fl_str_mv |
O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal |
dc.title.alternative.eng.fl_str_mv |
Involvement of the paraventricular nucleus of the hypothalamus in the maintenance of blood pressure and modulation of renal sympathetic tone of rats treated with in a sodium rich diet in the post natal phase |
title |
O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal |
spellingShingle |
O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal Almeida, Melissa Tavares Sobrecarga de sódio Doenças cardiovasculares Atividade nervosa simpática renal Pressão arterial Ingestão de sódio Estrógeno Sodium overload Cardiovascular diseases Renal sympathetic nervous activity Blood pressure Sodium intake Estrogen CIENCIAS BIOLOGICAS::FISIOLOGIA |
title_short |
O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal |
title_full |
O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal |
title_fullStr |
O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal |
title_full_unstemmed |
O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal |
title_sort |
O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal |
author |
Almeida, Melissa Tavares |
author_facet |
Almeida, Melissa Tavares |
author_role |
author |
dc.contributor.advisor1.fl_str_mv |
Pedrino, Gustavo Rodrigues |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/1155446449250341 |
dc.contributor.advisor-co1.fl_str_mv |
Mourão, Aline Andrade |
dc.contributor.advisor-co1Lattes.fl_str_mv |
http://lattes.cnpq.br/1596884578398481 |
dc.contributor.referee1.fl_str_mv |
Ferreira-Neto, Marcos Luiz |
dc.contributor.referee2.fl_str_mv |
Mendes, Elizabeth Pereira |
dc.contributor.referee3.fl_str_mv |
Pedrino, Gustavo Rodrigues |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/6583838264355921 |
dc.contributor.author.fl_str_mv |
Almeida, Melissa Tavares |
contributor_str_mv |
Pedrino, Gustavo Rodrigues Mourão, Aline Andrade Ferreira-Neto, Marcos Luiz Mendes, Elizabeth Pereira Pedrino, Gustavo Rodrigues |
dc.subject.por.fl_str_mv |
Sobrecarga de sódio Doenças cardiovasculares Atividade nervosa simpática renal Pressão arterial Ingestão de sódio Estrógeno |
topic |
Sobrecarga de sódio Doenças cardiovasculares Atividade nervosa simpática renal Pressão arterial Ingestão de sódio Estrógeno Sodium overload Cardiovascular diseases Renal sympathetic nervous activity Blood pressure Sodium intake Estrogen CIENCIAS BIOLOGICAS::FISIOLOGIA |
dc.subject.eng.fl_str_mv |
Sodium overload Cardiovascular diseases Renal sympathetic nervous activity Blood pressure Sodium intake Estrogen |
dc.subject.cnpq.fl_str_mv |
CIENCIAS BIOLOGICAS::FISIOLOGIA |
description |
High sodium intake can affect the excitability of neurons in regions responsible for the control of sympathetic nervous activity. It is known that the neuronal activity of the hypothalamus paraventricular nucleus (PVN) is increased in several models of sodium-sensitive arterial hypertension (SSH). Diseases that develop in adulthood are related to certain exposures suffered by the individual during the early stages of life. However, the literature point out differences between males and females in the expression of hypertension in both animal and human models, and in females, estrogen sometimes has a cardioprotective effect. In the present study, we investigated whether changes in diet during the postnatal phases contribute to central alterations in the control of renal sympathetic tone in males and females, and whether they persist in adulthood. More specifically, we evaluated the contribution of the PVN in the control of cardiovascular parameters and sympathetic nervous activity (SNA) after treatment with a sodium-rich diet for 30 days in adult rats and rats. Twenty one days old wistar male and female rats were divided into two groups: control group, composed of males (MCTRL) and females (FCTRL), maintained with water; and experimental group, composed of males (MEXP) and females (FEXP), maintained with hypertonic solution of 0.3 M NaCl. Animals of all groups received chow and hypertonic solution or water ad libitum for 30 days. After treatment, the animals of all groups were maintained with water and chow for 15 days (recovery period). Daily food and fluid (0.3 M NaCl or water) intake and body weight were monitored during the treatment and recovery periods. At the end of treatment, the treated male rats were found to have lower body weight compared to controls (MEXP (n = 9): 115.3 ± 4.7 g vs. MCTRL (n = 9): 168.0 ± 8.0 g, p <0.05). However, this difference was not observed between the experimental and control female groups (FEXP (n = 8): 119.5 ± 5.3 g vs. FCTRL (n = 8): 134.1 ± 5.2 g). We also observed that the experimental animals ingested a greater amount of fluid per gram of body weight (bw) than control animals MEXP (n=9): 0.717 ± 0.120 mL/g/bw vs. MCTRL (n=9): 0.209; FEXP (n=8): 0.576 ± 0.060 mL/g/bw vs. FCTRL (n=8): 0.251 ± 0.011 mL/g/bw, p < 0.05) and we observed a decrease in the excreted volume (Vexc) in experimental females compared to the ingested volume (Ving) (FEXP (n=8): Ving 89.6 ± 5.6 mL vs. Vexc 56.8 ± 5.2 mL, p < 0.05). In the recovery period there was no difference in daily water intake between groups (MEXP (n=9): 0.203 ± 0.008 mL/g/bw vs. MCTRL (n=9): 0,171 ± 0.005 mL/g/bw; FEXP (n=8): 0,229 ± 0,013 mL/g/bw vs. FCTRL (n=8): 0.187 ± 0,010 mL/g/bw). In another set of experiments, we evaluated the participation of the PVN in the maintenance of sympathetic tonus after treatment with a high sodium diet for 30 days. Bilateral nanoinjections of 50 nL of muscimol (GABAA agonist, 4 mM) were performed in the PVN in experimental and control animals during recording of mean arterial pressure (MAP), heart rate (HR) and renal SNA (RSNA). It is noteworthy that in the females these experiments were performed in the diestrus of the estrous cycle. In the anaesthetized experiments, the males of the treated group showed higher values of baseline MAP compared to both control male group and to female groups (PAM: MEXP (n=6): 108.2 ± 2.9 mmHg vs. MCTRL (n=6): 92 ± 5.4 mmHg vs. FEXP (n=6): 102.7 ± 4.4 mmHg vs. FCTRL (n=6): 90.8 ± 1.8 mmHg, p<0.05). Inhibition of the PVN promoted a reduction on MAP of experimental groups when compared to control groups: (Δ MAP: MEXP (n=6): -14.9 ± 1.5 mmHg vs. MCTRL (n=6): -7.2 ± 0.7 mmHg vs. FEXP (n=6): -12.9 ± 1.7 mmHg vs. FCTRL (n=6): -4.8 ± 0.6 mmHg, p <0.05). On the other hand, no differences were observed in the HR responses of the evaluated groups (Δ HR: MEXP (n=6): -35.8 ± 6.6 bpm vs. MCTRL (n=6): -21.6 ± 2.9 bpm vs. FEXP (n=6): -27.8 ± 3.5 bpm vs. FCTRL (n=6): -31.0 ± 4.4 bpm). In addition, acute inhibition of PVN promoted renal sympathoinhibition in experimental animals compared to controls (Δ % ANSR: MEXP (n=6): -17.3 ± 1.5% vs. MCTRL (n=6): -6.8 ± 1.0% vs. FEXP (n=6): -18.1 ± 0.5% vs. FCTRL (n=6): -3.0 ± 0.6%, p <0.05). The results demonstrated in the present study showed that the hypersodiuc diet during the early stages of life altered baseline MAP of experimental males. Additionally, we observed that the acute inhibition of PVN promoted cardiovascular and sympathetic changes in rats treated with a high sodium diet in comparison to the control group. Taken together, the observed results add new information to the literature and suggest that cardiovascular and sympathetic control regions, such as the PVN, may be more involved in the tonic modulation of blood pressure and RSNA in response to sodium overload in the postnatal phase of normotensive rats. Finally, our study points to the possibility that estrogen may have helped decrease the high blood pressure promoted by prolonged increase in sodium intake, but it was not enough to prevent the increase in the modulation of the sympathetic tone exerted by the PVN. However, future studies are needed to investigate pathways and mechanisms involved in these responses. |
publishDate |
2019 |
dc.date.accessioned.fl_str_mv |
2019-07-04T15:02:00Z |
dc.date.issued.fl_str_mv |
2019-06-28 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
ALMEIDA, M. T. O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal. 2019. 73 f. Dissertação (Mestrado Ciências Fisiológicas) - Universidade Federal de Goiás, Goiânia, 2019. |
dc.identifier.uri.fl_str_mv |
http://repositorio.bc.ufg.br/tede/handle/tede/9791 |
dc.identifier.dark.fl_str_mv |
ark:/38995/0013000004mb0 |
identifier_str_mv |
ALMEIDA, M. T. O envolvimento do núcleo paraventricular do hipotálamo na manutenção da pressão arterial e modulação do tônus simpático renal de ratos tratados com dieta rica em sódio na fase pós natal. 2019. 73 f. Dissertação (Mestrado Ciências Fisiológicas) - Universidade Federal de Goiás, Goiânia, 2019. ark:/38995/0013000004mb0 |
url |
http://repositorio.bc.ufg.br/tede/handle/tede/9791 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.relation.program.fl_str_mv |
1337318928839825463 |
dc.relation.confidence.fl_str_mv |
600 600 600 600 |
dc.relation.department.fl_str_mv |
-3872772117827373404 |
dc.relation.cnpq.fl_str_mv |
7737708247419018223 |
dc.relation.sponsorship.fl_str_mv |
-961409807440757778 |
dc.rights.driver.fl_str_mv |
http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess |
rights_invalid_str_mv |
http://creativecommons.org/licenses/by-nc-nd/4.0/ |
eu_rights_str_mv |
openAccess |
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application/pdf |
dc.publisher.none.fl_str_mv |
Universidade Federal de Goiás |
dc.publisher.program.fl_str_mv |
Programa de Pós-graduação em Ciências Fisiológicas - Multicêntrico (ICB) |
dc.publisher.initials.fl_str_mv |
UFG |
dc.publisher.country.fl_str_mv |
Brasil |
dc.publisher.department.fl_str_mv |
Instituto de Ciências Biológicas - ICB (RG) |
publisher.none.fl_str_mv |
Universidade Federal de Goiás |
dc.source.none.fl_str_mv |
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