Navegando por Autor "Abreu, Aline Rezende Ribeiro de"

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Abdominal TRPV1 channel desensitization enhances stress-induced hyperthermia during social stress in rats.
(2023) Reis, Thayane Oliveira; Noronha, Sylvana Izaura Salyba Rendeiro de; Lima, Paulo Marcelo de Andrade; Abreu, Aline Rezende Ribeiro de; Mesquita, Laura Batista Tavares; Ferreira, Fernanda Isabel; Silva, Fernanda Cacilda dos Santos; Chianca Júnior, Deoclécio Alves; Menezes, Rodrigo Cunha Alvim de
Aims: In rats, stress-induced hyperthermia caused by social interaction depends on brown adipose tissue (BAT) thermogenesis and peripheral vasoconstriction. However, the peripheral mechanisms responsible for regulating the level of hyperthermia during social stress are still unknown. The transient receptor potential vanilloid 1 (TRPV1) subfamily, expressed in sensory and visceral neurons, can serve as a thermoreceptor. Here, we tested the hypothesis that the abdominal TRPV1 is essential in regulating stress-induced hyperthermia during social stress. Main methods: Male Wistar rats received an intraperitoneal injection of Resiniferatoxin (RTX) - an ultra-potent capsaicin analog, (i.e., to desensitize the TRPV1 channels) or vehicle. Seven days later, we evaluated the effects of abdominal TRPV1 channels desensitization on core body temperature (CBT), brown adipose tissue (BAT) temperature, tail skin temperature, and heart rate (HR) of rats subjected to a social stress protocol. Key findings: We found abdominal TRPV1 desensitization increased CBT and BAT temperature but did not change tail skin temperature and HR during rest. However, under social stress, we found that abdominal TRPV1 desensitization heightened the increase in CBT and BAT caused by stress. Also, it abolished the increase in tail skin temperature that occurs during and after social stress. TRPV1 desensitization also delayed the HR recovery after the exposure to the social stress. Significance: These results show that abdominal TRPV1 channels desensitization heightens stress-induced hyperthermia, causing heat dissipation during and after social stress, enabling optimal thermal control during social encounters.
Association of high-fat diet with neuroinflammation, anxiety-like defensive behavioral responses, and altered thermoregulatory responses in male rats.
(2019) Noronha, Sylvana Izaura Salyba Rendeiro de; Lima, Paulo Marcelo de Andrade; Campos, Glenda Siqueira Viggiano; Chírico, Máira Tereza Talma; Abreu, Aline Rezende Ribeiro de; Figueiredo, Amanda Braga de; Silva, Fernanda Cacilda dos Santos; Chianca Júnior, Deoclécio Alves; Lowry, Christopher; Menezes, Rodrigo Cunha Alvim de
Overweight and obesity are a worldwide pandemic affecting billions of people. These conditions have been associated with a chronic low-grade inflammatory state that is recognized as a risk factor for a range of somatic diseases as well as neurodevelopmental disorders, anxiety disorders, trauma- and stressor-related disorders, and affective disorders. We previously reported that the ingestion of a high-fat diet (HFD; 45% fat kcal/g) for nine weeks was capable of inducing obesity in rats in association with increased reactivity to stress and increased anxiety-related defensive behavior. In this study, we conducted a nine-week diet protocol to induce obesity in rats, followed by investigation of anxiety-related defensive behavioral responses using the elevated T-maze (ETM), numbers of FOS-immunoreactive cells after exposure of rats to the avoidance or escape task of the ETM, and neuroinflammatory cytokine expression in hypothalamic and amygdaloid nuclei. In addition, we investigated stress-induced cutaneous thermoregulatory responses during exposure to an open-field (OF). Here we demonstrated that nine weeks of HFD intake induced obesity, in association with increased abdominal fat pad weight, increased anxiety-related defensive behavioral responses, and increased proinflammatory cytokines in hypothalamic and amygdaloid nuclei. In addition, HFD exposure altered avoidance- or escape task-induced FOSimmunoreactivity within brain structures involved in control of neuroendocrine, autonomic, and behavioral responses to aversive stimuli, including the basolateral amygdala (BLA) and dorsomedial (DMH), paraventricular (PVN) and ventromedial (VMH) hypothalamic nuclei. Furthermore, rats exposed to HFD, relative to control dietfed rats, responded with increased tail skin temperature at baseline and throughout exposure to an open-field apparatus. These data are consistent with the hypothesis that HFD induces neuroinflammation, alters excitability of brain nuclei controlling neuroendocrine, autonomic, and behavioral responses to stressful stimuli, and enhances stress reactivity and anxiety-like defensive behavioral responses.
Avaliação da vulnerabilidade às respostas do tipo pânico em ratos com obesidade induzida por dieta hiperlipídica.
(2016) Abreu, Aline Rezende Ribeiro de; Menezes, Rodrigo Cunha Alvim de; Shekhar, Anantha; Chianca Júnior, Deoclécio Alves; Menezes, Rodrigo Cunha Alvim de; Oliveira, Lisandra Brandino de; Zangrossi Júnior, Hélio; Fontes, Marco Antônio Peliky; Moreira, Fabrício de Araújo
Estudos anteriores de nosso laboratório demonstraram que a obesidade, induzida por uma dieta hiperlipídica, potencializa a resposta cardiovascular produzida pelo estresse de jato de ar em ratos. Esta resposta aumentada é devido a uma redução da inibição mediada por GABA no DMH, já que a ativação de receptores de GABAA foi menos eficaz na redução das respostas fisiológicas provocadas pelo estresse de ar em ratos obesos. Além disso, há evidências que indicam uma associação entre essa redução crônica da função GABA no DMH e desenvolvimento de desordens de ansiedade, como o transtorno do pânico. Portanto, o objetivo deste estudo foi avaliar a vulnerabilidade às respostas do tipo pânico em ratos com obesidade induzida por dieta hiperlipídica. Ratos Wistar (100 ± 10 g) foram alimentados com uma dieta de controle – DC, ou uma dieta hiperlipídica - DH (45 %) durante 9 semanas. Em um primeiro momento, um grupo de animais foi anestesiado (cetamina/xilazina) e submetidos a implante unilateral de cânula guia no DMH para posterior microinjeção de agonistas de receptor glutamatérgico (NMDA e não NMDA: AMPA). Observamos que tanto a microinjeção de NMDA quanto de AMPA no DMH dos ratos controles e obesos provocaram aumentos de PAM e FC. Interessantemente, a microinjeção de NMDA gerou uma resposta taquicárdica de curta duração e a microinjeção de AMPA produziu uma resposta pressórica exacerbada nos animais obesos em relação aos controles. Com o intuito de avaliar o efeito da infusao de lactato em animais com obesidade induzida por dieta hiperlipídica, seja alojado individualmente ou coletivamente, outro grupo de animais foi anestesiado (isoflurano) e submetidos a implante de cateter na artéria e veia femoral para aquisiçāo dos parâmetros cardiovasculares (PAM e FC), e infusões de soluções, respectivamente. Após período de recuperação, os ratos foram submetidos a dois testes diferentes, e de modo aleatório, em que recebiam infusões de solução salina 0,9% e 0,5 M de lactato de sódio-NaLac (10 ml/kg ao longo de 15 min). As respostas máximas para lactato (PAM e FC) relatadas são as diferenças entre as alterações induzidas pelas infusões de lactato e salina. Os resultados demonstraram que apesar da infusão de NaLac não alterar a PAM, nem nos grupos obesos coletivos tampouco nos individuais, induziu um aumento significativo da FC em ambos os grupos obesos (coletivo e individual), e ao final do período de recuperação essas alterações taquicardias anteriormente observadas em animais individuais obesos, foram mantidas. Em um terceiro momento, um outro grupo de animais foram anestesiados da mesma maneira (isoflurano), mas receberam, por sua vez, implantes de telemetria para posterior exposição a 7,5% CO2. Observamos que os ratos obesos apresentaram alta PAM basal o que levou a uma maior resposta PAM final seguida de CO2 nesse grupo. Não houve diferenças observadas na frequência cardíaca (FC) antes do desafio com o gás, já durante o desafio, os animais obesos, mas não os controles, tiveram um aumento na FC (interação dieta x gás). Nós, então, avaliamos as alterações comportamentais de animal obeso e controle durante o teste comportamental do Labirinto em T elevado (LTE). Nossos resultados demonstraram que os animais obesos apresentam comportamento do associado a ansiedade, evidenciado pelo aumento no tempo de latência no braço fechado neste aparato quando comparado aos animais controle, no entanto não apresentaram comportamento associado ao pânico. Esses resultados sugerem que a obesidade induzida por dieta hiperlipídica leva a desinibição do circuito de pânico que contribui para a vulnerabilidade as respostas do tipo pânico seguidas pela infusão de NaLac ou durante exposição dos ratos a 7,5 % CO2.
Blunted gaba-mediated inhibition within the dorsomedial hypothalamus potentiates the cardiovascular response to emotional stress in rats fed a high-fat diet.
(2014) Abreu, Aline Rezende Ribeiro de; Abreu, Alessandra Rezende Ribeiro de; Santos, Laura Tavares; Souza, Aline Maria Arlindo de; Silva Junior, Luiz Gonzaga da; Chianca Júnior, Deoclécio Alves; Menezes, Rodrigo Cunha Alvim de
Rats fed a high-fat diet (HFD) present an exaggerated endocrine response to stress conditions, which, like obesity, show a high correlation with cardiovascular diseases. Meanwhile the GABAergic neurotransmission within the dorsomedial hypothalamus (DMH) is involved in the regulation of the physiological responses during emotional stress. Here we evaluated the influence of obesity, induced by a HFD, on the cardiovascular responses induced by air jet stress in rats, and the role of the GABAergic tonus within the DMH in these changes. Our results showed that consumption of a HFD (45% w/w fat) for 9 weeks induced obesity and increases in baseline mean arterial pressure (MAP) and heart rate (HR). Moreover, obesity potentiated stress responsiveness, evidenced by the greater changes in MAP and HR induced by stress in obese rats. The injection of muscimol into the DMH reduced the maximal increases in HR and MAP induced by stress in both groups; however, the reduction in the maximal increases in MAP in the HFD group was less pronounced. Moreover, the injection of muscimol into the DMH of obese rats was less effective in reducing the stress-induced tachycardia, since the HR attained the same levels at the end of the stress paradigm as after the vehicle injection. Injection of bicuculline into DMH induced increases in MAP and HR in both groups. Nevertheless, obesity shortened the tachycardic response to bicuculline injection. These data show that obesity potentiates the cardiovascular response to stress in rats due to an inefficient GABAA-mediated inhibition within the DMH.
Estrogen receptor β activation within dorsal raphe nucleus reverses anxiety-like behavior induced by food restriction in female rats.
(2018) Campos, Glenda Siqueira Viggiano; Noronha, Sylvana Izaura Salyba Rendeiro de; Souza, Aline Maria Arlindo de; Lima, Paulo Marcelo de Andrade; Abreu, Aline Rezende Ribeiro de; Chianca Júnior, Deoclécio Alves; Menezes, Rodrigo Cunha Alvim de
Severe food restriction (FR), as observed in disorders like anorexia nervosa, has been associated to the reduction of estrogen levels, which in turn could lead to anxiety development. Estrogen receptors, mainly ERβ type, are commonly found in the dorsal raphe nucleus (DRN) neurons, an important nucleus related to anxiety modulation and the primary source of serotonin (5-HT) in the brain. Taking together, these findings suggest an involvement of estrogen in anxiety modulation during food restriction, possibly mediated by ERβ activation in serotonergic DRN neurons. Thus, the present study investigated the relationship between food restriction and anxiety-like behavior, and the involvement of DRN and ERβ on the modulation of anxiety-like behaviors in animals subjected to FR. For that, female Fischer rats were grouped in control group, with free access to food, or a FR group, which received 40% of control intake during 14 days. Animals were randomly treated with 17β-estradiol (E2), DPN (ERβ selective agonist), or their respective vehicles, PBS and DMSO. Behavioral tests were performed on Elevated T-Maze (ETM) and Open Field (OF). Our results suggest that FR probably reduced the estrogen levels, since the remained in the non-ovulatory cycle phases, and their uterine weight was lower when compared to control group. The FR rats showed increased inhibitory avoidance latency in theETM indicating that FR is associated with the development of an anxiety-like state. The injections of both E2 and DPN into DRN of FR animals had an anxiolytic effect. Those data suggest thatanxiety-like behavior induced by FR could be mediated by a reduction of ERβ activation in the DRN neurons, probably due to decreased estrogen levels.
High fat diet induced-obesity facilitates anxiety-like behaviors due to GABAergic impairment within the dorsomedial hypothalamus in rats.
(2017) Noronha, Sylvana Izaura Salyba Rendeiro de; Campos, Glenda Siqueira Viggiano; Abreu, Aline Rezende Ribeiro de; Souza, Aline Maria Arlindo de; Chianca Júnior, Deoclécio Alves; Menezes, Rodrigo Cunha Alvim de
Overweight and obesity are conditions associated with an overall range of clinical health consequences, and they could be involved with the development of neuropsychiatric diseases, such as generalized anxiety disorder (GAD) and panic disorder (PD). A crucial brain nuclei involved on the physiological functions and behavioral responses, especially fear, anxiety and panic, is the dorsomedial hypothalamus (DMH). However, the mechanisms underlying the process whereby the DMH is involved in behavioral changes in obese rats still remains unclear. The current study further investigates the relation between obesity and generalized anxiety, by investigating the GABAA sensitivity to pharmacological manipulation within the DMH in obese rats during anxiety conditions. Male Wistar rats were divided in two experimental groups: the first was fed a control diet (CD; 11% w/w) and second was fed a high fat diet (HFD; 45% w/w). Animals were randomly treated with muscimol, a GABAA agonist and bicuculline methiodide (BMI), a GABAA antagonist. Inhibitory avoidance and escape behaviors were investigated using the Elevated T-Maze (ETM) apparatus. Our results revealed that the obesity facilitated inhibitory avoidance acquisition, suggesting a positive relation between obesity and the development of an anxiety-like state. The injection of muscimol (an anxiolytic drug), within the DMH, increased the inhibitory avoidance latency in obese animals (featuring an anxiogenic state). Besides, muscimol prolonged the escape latency and controlling the possible panic-like behavior in these animals. Injection of BMI into the DMH was ineffective to produce an anxiety-like effect in obese animals opposing the results observed in lean animals. These findings support the hypotheses that obese animals are susceptible to develop anxiety-like behaviors, probably through changes in the GABAergic neurotransmission within the DMH.
Increased α1-adrenoreceptor activity is required to sustain blood pressure in female rats under food restriction.
(2015) Souza, Aline Maria Arlindo de; Menezes, Rodrigo Cunha Alvim de; Abreu, Aline Rezende Ribeiro de; Araujo, Glaucy Rodrigues de; Costa, Daniela Caldeira; Chianca Júnior, Deoclécio Alves
Aims: Weevaluated the effect of food restriction (FR) on the various reflexes involved in short termcardiovascular regulation; we also evaluated the contribution of the sympathetic nervous systemand of the plasmatic nitric oxide (NO) in the development of the counterregulatory cardiovascular changes triggered by FR. Main methods: Female rats were subjected to FR for 14 days, and after this period biochemical measurements of biochemical parameterswere performed. For physiological tests, animalswere anaesthetised, and a catheter was inserted into the femoral artery and vein for the acquisition of blood pressure and heart hate, and drug infusion, respectively.We then tested the Bezold–Jarisch reflex, the baroreflex and chemoreflex and the effect of the infusion of adrenergic receptor antagonists in control and food restricted animals. Key findings: The rats subjected to severe FR presented biochemical changes characteristic ofmalnutrition with a great catabolic state. FR also led to hypotension and bradycardia besides reducing the plasmatic concentration of NO. Moreover, activation of the Bezold–Jarisch reflex induced a more pronounced hypotensive response in animals subjected to FR. Intravenous infusion of a α1-adrenoreceptor antagonist induced a greater hypotensive response and a more pronounced tachycardic response in animals under food restriction,while the infusion of β- adrenoreceptor antagonist induced lower increases in blood pressure in these animals. Significance: Our results suggest that an increased α1-adrenoreceptor activity in the resistance arteries coupled with a reduction of plasmatic NO contributes in a complementary manner to maintain the blood pressure levels in animals under FR.
Influência da amígdala basomedial no comportamento do tipo ansiedade em ratos Wistar.
(2019) Mesquita, Laura Batista Tavares; Menezes, Rodrigo Cunha Alvim de; Abreu, Aline Rezende Ribeiro de; Chianca Júnior, Deoclécio Alves; Moraes, Grace Schenatto Pereira; Menezes, Rodrigo Cunha Alvim de; Abreu, Aline Rezende Ribeiro de; Chianca Júnior, Deoclécio Alves; Moreira, Fabrício de Araújo; Silva, Fernanda Cacilda dos Santos; Almeida, Roberto Farina de
A amígdala tem sido vinculada a uma variedade de funções ligadas a respostas fisiológicas, comportamentais e endócrinas, relacionadas a estímulos emocionais. Esta região encefálica é composta por vários sub-núcleos, que embora pertencentes à mesma estrutura, podem se envolver em funções diferentes, o que torna o estudo de cada sub-núcleo de grande importância. Em um trabalho do nosso grupo de pesquisa, sugerimos que a amígdala basomedial (BMA) está sob ativação tônica, participando desta forma do controle cardiovascular de ratos, controlando respostas exacerbadas frente situações de estresse social. Partindo do pressuposto que mudanças autonômicas podem ser caracterizadas como causa ou efeito do comportamento do tipo ansiedade, o nosso objetivo é avaliar, por meio de manipulações químicas e quimiogenéticas, a influência da BMA nas repostas comportamentais do tipo ansiedade, bem como suas conexões com outras regiões cerebrais envolvidas nestas respostas. Para isso, um grupo de ratos Wistar recebeu o implante de cânulas-guia direcionados à BMA, bilateralmente, para injeção de drogas. Após sete dias, observamos que a inibição química da BMA por meio da microinjeção bilateral do agonista GABAA, muscimol (100pmol/100nL), diminuiu a interação social (IS) entre pares de animais. Por outro lado, observamos que ao ativarmos quimicamente esta região, pela microinjeção bilateral do antagonista GABAA, Bicuculline methochloride (BMC) (10pmol/100nL), houve aumento na IS entre os ratos. Apesar disso, ambas, inibição e ativação química da BMA não alteraram os parâmetros comportamentais analisados no teste de campo aberto (CA). Além do efeito ansiolítico entre pares de animais, a ativação química da BMA aumentou a atividade neuronal na região do núcleo do leito da estria terminal (BNST) e hipotálamo dorsomedial (HDM), além de demonstrar uma forte tendência de aumento nas regiões da área preóptica medial (mPOA) e coluna ventrolateral da substância cinzenta periaquedutal (vlPAG). A inibição química da BMA, por sua vez, não alterou a atividade neuronal das regiões analisadas, apesar da forte tendência de aumento de atividade na mPOA. Já outro grupo de ratos Wistar foi separado em dois sub-grupos: um deles recebeu a infusão na BMA de DREADD AAV5-CaMKII-hM3D(Gq)-mCherry e o outro de AAV5-CaMKIIhM3D(Gs)-IRES-mCitrine, e ambos infectam preferencialmente neurônios glutamatérgicos (400nL, bilateralmente). Após cinco semanas, no sub-grupo Gq, foi implantado uma sonda de telemetria para posterior aferição de pressão arterial (PA), frequência cardíaca (FC) e temperatura corporal. Observamos que, a ativação quimiogenética dos neurônios glutamatérgicos da BMA, após injeção i.p. de CNO (3mg/Kg), no sub-grupo Gq, aumentou a IS entre os ratos, sem efeitos no teste de CA. Já no sub-grupo Gs nenhum efeito foi observado em ambos os testes comportamentais. Na semana seguinte vimos que a ativação quimiogenética da BMA, nos animais do sub-grupo Gq, reduziu os aumentos de FC, PA e de temperatura corporal provocados pelo estresse por contenção. Após estresse, a ativação quimiogenética da BMA no sub-grupo Gs não foi capaz de alterar o comportamento dos animais. Já a redução do comportamento do tipo ansiedade social no sub-grupo Gq não ocorreu após estresse. Estes resultados sugerem que, tanto o bloqueio dos receptores gabaérgicos, quanto a ativação quimiogenética de neurônios glutamatérgicos na BMA, reduzem o comportamento do tipo ansiedade social e respostas de estresse, exercendo influência nestas situações por meio de conexões com regiões encefálicas também envolvidas em situações de defesa.
Influência da obesidade induzida por dieta hiperlipídica nas respostas cardiovasculares evocadas pelo estresse emocional em ratos.
(Programa de Pós-Graduação em Ciências Biológicas do Núcleo de Pesquisas em Ciências Biológicas. Departamento de Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto., 2012) Abreu, Aline Rezende Ribeiro de; Menezes, Rodrigo Cunha Alvim de
O hipotálamo dorsomedial (DMH) está envolvido na mediação das respostas funcionais durante o estresse (e.g.: nas alterações cardiovasculares em ratos submetidos ao estresse por jato de ar ou isolamento social). Estudos sugerem que ratos alimentados com uma dieta hiperlipídica (DH) apresentam uma resposta exagerada em condições de estresse e que este, assim como a obesidade apresenta forte associação com doenças cardiovasculares. O objetivo do nosso estudo foi avaliar a influência da obesidade induzida pela DH nas respostas cardiovasculares evocadas pelo estresse agudo em ratos Wistar. Para tal, 78 ratos (100±10g) foram alojados coletivamente (no máximo 3 ratos dentro de uma caixa de 41x34x17cm) ou individualmente (1 rato dentro de uma caixa de 30x19x13 cm) e alimentados, por 9 semanas, com dieta controle (Nuvilab®) ou DH contendo 11% e 45% Kcal/g de lipídio, respectivamente. Em seguida, os ratos foram submetidos ao implante bilateral ou unilateral de cânulas guia no DMH para microinjeção de muscimol (agonista GABAA;100pmol/100nL e veículo;100nL) seguido por estresse por jato de ar (15 min), ou de bicuculina (antagonista GABAA;10pmol/100nL e veículo;100nL). Implante de cateter na artéria femoral foi realizado para aquisição dos valores de pressão arterial média (PAM) e de freqüência cardíaca (FC). Nossos resultados mostraram que a DH foi eficiente em induzir obesidade dietética - comprovada pelo aumento do peso corporal, índice de Lee e índice de adiposidade - a qual aumentou os níveis de PAM e FC basais nos grupos coletivos. A obesidade potencializou as respostas cardiovasculares: respostas pressoras e taquicárdica quando comparadas com o grupo controle. Além disso, a microinjeção de muscimol reduziu ambas respostas nos grupos dieta, porém foi menos eficaz em reduzir a PAM no grupo obeso. Ao final do estresse, no período de recuperação, o grupo obeso desmonstrou-se menos responsivo ao muscimol (não reduziu PAM e FC). Já , tanto no grupo obeso individual quanto no controle individual, a microinjeção de muscimol não reduziu a PAM durante todo o período de estresse, porém, surpreendentemente, aumentou a resposta de FC ao estresse no grupo obeso. A microinjeção de bicuculina no DMH induziu aumento da PAM e FC em ambos os grupos. Contudo, a obesidade alterou a resposta taquicárdica à bicuculina evidenciada por sua curta duração. Esses dados sugerem que a obesidade induzida por dieta hiperlipídica em ratos alterou PAM e FC basais e evocadas pelo estresse agudo, provavelmente, pela ineficiência da inibição sináptica mediada pelo receptor GABAA sobressaindo à ativação sináptica excitatória.
New insights on amygdala : basomedial amygdala regulates the physiological response to social novelty.
(2016) Mesquita, Laura Batista Tavares; Abreu, Aline Rezende Ribeiro de; Abreu, Alessandra Rezende Ribeiro de; Souza, Aline Maria Arlindo de; Noronha, Sylvana Izaura Salyba Rendeiro de; Silva, Fernanda Cacilda dos Santos; Campos, Glenda Siqueira Viggiano; Chianca Júnior, Deoclécio Alves; Menezes, Rodrigo Cunha Alvim de
The amygdala has been associated with a variety of functions linked to physiological, behavioral and endocrine responses during emotional situations. This brain region is comprised of multiple sub-nuclei. These subnuclei belong to the same structure, but may be involved in different functions, thereby making the study of each sub-nuclei important. Yet, the involvement of the basomedial amygdala (BMA) in the regulation of emotional states has yet to be defined. Therefore, the aim of our study was to investigate the regulatory role of the BMA on the responses evoked during a social novelty model and whether the regulatory role depended on an interaction with the dorsomedial hypothalamus (DMH). Our results showed that the chemical inhibition of the BMA by the microinjection of muscimol (c-aminobutyric acid (GABAA) agonist) promoted increases in mean arterial pressure (MAP) and heart rate (HR), whereas the chemical inhibition of regions near the BMA did not induce such cardiovascular changes. In contrast, the BMA chemical activation by the bilateral microinjection of bicuculline methiodide (BMI; GABAA antagonist), blocked the increases in MAP and HR observed when an intruder rat was suddenly introduced into the cage of a resident rat, and confined to the small cage for 15 min. Additionally, the increase in HR and MAP induced by BMA inhibition were eliminated by DMH chemical inhibition. Thus, our data reveal that the BMA is under continuous GABAergic influence, and that its hyperactivation can reduce the physiological response induced by a social novelty condition, possibly by inhibiting DMH neurons.
Role of the renin angiotensin system in blood pressure allostasis-induced by severe food restriction in female Fischer rats.
(2018) Souza, Aline Maria Arlindo de; West, Crystal A.; Abreu, Aline Rezende Ribeiro de; Pai, Amrita V.; Mesquita, Laura Batista Tavares; Ji, Hong; Chianca Júnior, Deoclécio Alves; Menezes, Rodrigo Cunha Alvim de; Sandberg, Kathryn
Severe food restriction (FR) is associated with blood pressure (BP) and cardiovascular dysfunction. The renin-angiotensin system (RAS) regulates BP and its dysregulation contributes to impaired cardiovascular function. Female Fischer rats were maintained on a control (CT) or severe FR (40% of CT) diet for 14 days. In response to severe FR, BP allostasis was achieved by up-regulating circulating Ang-[1–8] by 1.3-fold through increased angiotensin converting enzyme (ACE) activity and by increasing the expression of AT1Rs 1.7-fold in mesenteric vessels. Activation of the RAS countered the depressor effect of the severe plasma volume reduction (≥30%). The RAS, however, still underperformed as evidenced by reduced pressor responses to Ang-[1–8] even though AT1Rs were still responsive to the depressor effects of an AT1R antagonist. The aldosterone (ALDO) response was also inadequate as no changes in plasma ALDO were observed after the large fall in plasma volume. These findings have implications for individuals who have experienced a period(s) of severe FR (e.g., anorexia nervosa, dieters, natural disasters) and suggests increased activity of the RAS in order to achieve allostasis contributes to the cardiovascular dysfunction associated with inadequate food intake.
Thermoregulatory responses, heart rate, and the susceptibility to anxiety in obese animals subjected to stress.
(2023) Santos, Áquila Rodrigues Costa; Abreu, Aline Rezende Ribeiro de; Noronha, Sylvana Izaura Salyba Rendeiro de; Reis, Thayane Oliveira; Santos, Daisy Motta; Chianca Júnior, Deoclécio Alves; Silva Junior, Luiz Gonzaga da; Menezes, Rodrigo Cunha Alvim de; Rodrigues, Cibele Velloso
Obesity and stress are related to cardiovascular diseases. Rats fed a high-fat diet (HFD) show increased cardiovascular reactivity to emotional stress and altered defensive behavioral responses. Indeed, changes in thermoregulatory responses in an aversive environment are observed in these animals. However, studies aimed at clarifying the physiological mechanisms linking obesity, stress hyperreactivity and behavioral changes are needed. The aim of this study was to evaluate the changes in thermoregulatory responses, heart rate, and the susceptibility to anxiety in obese animals subjected to stress. Nine-week high-fat diet protocol was effective in inducing obesity by increasing weight gain, fat mass, adiposity index, white epididymal, retroperitoneal, inguinal and brown adipose tissue. Animals induced to obesity and subjected to stress (HFDS group) by the intruder animal method showed increases in heart rate (HR), core body temperature and tail temperature. HFDS showed an increase in the first exposure to the closed arm (anxiety-like behavior) in elevated T-Maze (ETM). The groups did not differ with respect to panic behavior assessed in the ETM and locomotor activity in the open field test. Our study shows that HFDS animals presented increased reactivity to stress with higher stress hyperthermia and anxious behavior. Thus, our results present relevant information regarding stress responsiveness and behavioral changes in obese animals.