Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-09-23T12:35:49Z No. of bitstreams: 1 DissJMIM.pdf: 1160970 bytes, checksum: 5d770f3bd6013be1ec19d00de0a6da90 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-04T17:59:57Z (GMT) No. of bitstreams: 1 DissJMIM.pdf: 1160970 bytes, checksum: 5d770f3bd6013be1ec19d00de0a6da90 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-04T18:00:03Z (GMT) No. of bitstreams: 1 DissJMIM.pdf: 1160970 bytes, checksum: 5d770f3bd6013be1ec19d00de0a6da90 (MD5) / Made available in DSpace on 2016-10-04T18:00:10Z (GMT). No. of bitstreams: 1 DissJMIM.pdf: 1160970 bytes, checksum: 5d770f3bd6013be1ec19d00de0a6da90 (MD5) Previous issue date: 2015-09-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Locus coeruleus (LC) is a pontine noradrenergic group that acts as a central chemoreceptor to CO2/pH and it is involved in the cognitive aspects of stress response and it is associated with a large number of physiological and behavioral processes, including sleepwake cycle, feeding, cardiovascular and respiratory control, nociception, thermoregulation and learning. The LC has also been implicated in the cognitive aspects of stress responses, in part through the action of corticotropin releasing factor (CRF), which when released in these situations increases the firing frequency of LC noradrenergic neurons. CRF is the largest stimulator of the pituitary secretion of ACTH (adrenocorticotropic hormone) and their receptors (types 1 and 2) are widely distributed in the central nervous system, including the LC. Thus, we tested the involvement of CRF1 receptors (CRF1) located in the LC in the ventilatory and thermal responses induced by hypercapnia (7%CO2) in rats. To this end, we injected antalarmin (a CRF1 antagonist, 0.05 and 0,1 μg/0.1 μL) into the LC of male Wistar rats. Pulmonary ventilation (VE) and body temperature (Tb, dataloggers) were measured in air and followed by 7% CO2 in unanesthetized rats. There were no differences in body temperature between groups under normocapnia and hypercapnia. We observed an increased ventilation in normocapnia, at 5 to 15 minutes after microinjection of antalarmin (dose 0.1 μg / 0.1 μL) compared to the control, due to an increase in tidal volume. The hypercapnic response in antalarmine treated animals was higher compared to control groups. The dose of 0.05 μg / 0.1 μL caused an increase in ventilation 15 min after CO2 exposure and this response increased further with the dose of 0.1 μg / 0.1 μL at 30 minutes after hypercapnia, due to an increased tidal volume. Our results suggest that CRF1 receptors in the LC exert a tonic inhibitory role in the ventilation and the inhibitory modulation of the respiratory response to CO2. / O locus coeruleus (LC) é um grupamento noradrenérgico pontino que atua como um quimiorreceptor central a CO2/pH e está associado a um grande número de processos fisiológicos e comportamentais, entre eles, ciclo sono-vigília, alimentação, controle respiratório e cardiovascular, nocicepção, termorregulação e aprendizado. O LC tem sido também implicado nos aspectos cognitivos na resposta ao stress, em parte por meio da ação do fator liberador de corticotrofina (CRF) que, ao ser liberado nessas situações, aumenta a frequência de disparo dos neurônios noradrenérgicos do LC. O CRF é o maior estimulador da secreção hipofisária de ACTH (hormônio adrenocorticotrófico), sendo que seus receptores (tipos 1 e 2) estão difusamente distribuídos no sistema nervoso central (SNC), incluindo o LC. Neste contexto, nós testamos o envolvimento dos receptores CRF1 no LC na resposta respiratória ao CO2 em ratos adultos não anestesiados, por meio da microinjeção de antalarmina (antagonista de CRF1) no LC (0,05 e 0,1 μg / 0,1 μL). A ventilação pulmonar (VE) e a temperatura corporal (Tc, dataloggers) foram medidas no ar e seguido de 7% CO2 em ratos não anestesiados. Não houve alteração na Tc entre os grupos em normocapnia e hipercapnia. Observamos aumento da ventilação em normocapnia, nos tempos de 5 a 15 minutos após a microinjeção de antalarmina (dose 0,1 μg / 0,1 μL) em comparação ao controle, devido a um aumento do volume corrente. A resposta hipercápnica de animais tratados com o antagonista de CRF1 foi maior em ambas as doses administradas, a dose de 0,05 μg / 0,1 μL provocou um aumento da ventilação em 15 min após a exposição CO2, e essa resposta aumentou ainda mais na dose de 0,1 μg / 0,1 μL em 30 minutos após a exposição CO2 em comparação com animais tratados com veículos, devido a um aumento do volume corrente. Nossos resultados sugerem que os receptores CRF1 no LC exercem um papel inibitório tônico na ventilação e a modulação inibitória na resposta respiratória ao CO2.

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No. of bitstreams: 1 DissCLT.pdf: 2731687 bytes, checksum: cf87ca5f5acf4b4eae6316a5a028b147 (MD5) Previous issue date: 2012-06-04 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The noradrenergic A5 group is an important group of neurons located in the ventrolateral pons and receives projections from several medullar areas related to cardiorespiratory regulation. The A5 region contributes to the maturation of the respiratory system before birth and in adult rats these neurons are connected with the neural network responsible for respiratory rhythmogenesis. The A5 neurons have an important involvement in autonomic control, these neurons send and receive projections from various regions involved in cardiovascular control, and send projections directly to the intermidial column lateral. Thus, we tested the hypothesis that noradrenergic neurons of A5 region participate in cardiorespiratory responses produced by hypercapnia or hypoxia in anesthetized and ananesthetized rats. In ananesthetized animals without and sino-aortic denervation, the lesion of the noradrenergic neurons in the A5 region with anti-dopamine β-hydroxylase-saporin (anti-DβH-SAP, 4.2 ng) promoted a decrease of tidal volume response to acute hypercapnia (7% CO2, 30 minutes) and acute hypoxia (7% O2, 30 minutes), but did not alter the cardiovascular response. In anesthetized animals during the acute hypercapnia (5% to 10% CO2, 5 minutes), the bilateral microinjection of muscimol (GABA-A agonist; 2 mM) and the chemical injury with anti-DβH-SAP on the A5 region reduced the increase of mean arterial pressure (MAP), splanchnic sympathetic activity (sSNA), frequency and amplitude of phrenic nerve produced by hypercapnia. During acute hypoxia (8-10% O2, 30 seconds) the bilateral microinjection of muscimol in the A5 region attenuated the increase in MAP and sSNA promoted by hypoxia without affecting the activity of the phrenic nerve, but the chemical injury of A5 region not altered responses promoted by hypoxia. The results of this study show that the participation of the A5 region in cardiorespiratory response depends on the animal's condition, anesthetized or not, as well as CO2 and O2 levels. In animals ananesthetized, the noradrenergic neurons of A5 region exert an excitatory modulation in control of tidal volume in response to hypercapnia and hypoxia. While in anesthetized animals, this region stimulates the cardiorespiratory response to hypercapnia, increasing the amplitude and frequency of the phrenic nerve, and sympathetic activity. / O grupamento noradrenérgico A5 representa um importante conjunto de neurônios localizado na ponte ventrolateral e recebe projeções de várias áreas do bulbo relacionadas com a regulação cardiorrespiratória. A região A5 contribui para a maturação do sistema respiratório antes do nascimento e em ratos adultos esses neurônios estão conectados com a rede neural responsável pela ritmogênese respiratória. Os neurônios da região A5 apresentam um importante envolvimento no controle autonômico, pois envia e recebe projeções de várias regiões envolvidas no controle cardiovascular, além de enviar projeções diretamente para a coluna intermédio lateral. Assim, testamos a hipótese de que os neurônios noradrenérgicos da região A5 participam das respostas cardiorrespiratórias produzidas pela hipercapnia ou hipóxia, em ratos anestesiados e não anestesiados. Em animais não anestesiados, sem e com desnervação sino-aórtica, a lesão dos neurônios noradrenérgicos da região A5 com anti- dopamina β-hidroxilase-saporina (anti-DβH-SAP; 4,2 ng) promoveu uma redução do volume corrente da resposta ventilatória à hipercapnia (7% CO2, 30 minutos) e hipóxia aguda (7% O2, 30 minutos), mas não alterou a resposta cardiovascular. Em animais anestesiados, durante a hipercapnia aguda (5% a 10% CO2, 5 minutos), a microinjeção bilateral de muscimol (agonista GABA-A; 2 mM) e a lesão química com anti-DβH-SAP na região A5 reduziram o aumento da pressão arterial média (PAM), atividade simpática esplâncnica (sSNA), frequência e amplitude do nervo frênico produzidas por hipercapnia. Durante a hipóxia aguda (8-10% O2, 30 segundos) a microinjeção bilateral de muscimol na região A5 atenuou o aumento da PAM e da sSNA promovido pela hipóxia, sem afetar a atividade do nervo frênico, porém a lesão química da região A5 não alterou as respostas promovidas pela hipóxia. Os resultados do presente trabalho demonstram que a participação da região A5 na resposta cardiorrespiratória depende do estado do animal, anestesiado ou não, bem como os níveis de CO2 e O2. Em animais não anestesiados, os neurônios noradrenérgicos da região A5 exercem uma modulação excitatória no controle do volume corrente em resposta à hipercapnia e hipóxia. Enquanto em animais anestesiados, essa região estimula a resposta cardiorrespiratória à hipercapnia, aumentando a amplitude e frequência do nervo frênico, e atividade simpática.

Hard clams, Mercenaria mercenaria, are slow-moving organisms that are heavily preyed upon by both blue crabs and knobbed whelks in coastal Georgia. Hard clams are unable to escape from these predators, and when found, are commonly injured and/or consumed. Thus, their best survival strategy is to avoid their predators. In this study, we compared changes in clam behavior when exposed to blue crab and knobbed whelk predators. Clams reduced their feeding time when exposed to crabs and whelks, exudates from these predators, and to injured conspecifics. In a field experiment, we compared clam survival when caged predators where near clam beds vs. controls with empty cages. Clam survival was significantly higher when caged crabs or whelks were near, suggesting that clams detected these predators, reduced their feeding time, and were less apparent to ambient consumers. In lab behavioral assays, clams were less responsive to blue crabs in turbulent flows, and in the field, turbulence reduced the distance clams reacted to blue crabs. Previous studies have shown that blue crabs turbulence also diminishes blue crab foraging efficiency, and we conducted a field experiment to determine how turbulence affected clam-crab interactions. Our results suggest that predation intensity is greatest at intermediate turbulence levels, and lowest in flows with low and high turbulence levels. We attribute this pattern of predation intensity to differential effects of turbulence on the sensory abilities of crabs and clams. That is, in low turbulent flows, clams have a sensory advantage over crabs, and initiate avoidance behaviors before they are detected. However, as turbulence increases, clam perception diminishes faster than crabs, switching the sensory advantage to crabs, and making clams more vulnerable to consumers. In highly turbulent flows, crab perception declines at a rate faster than clams, and the sensory advantage returns to clams.

This collection of research examines how changes in the sensory landscape, mediated by both odor and hydrodynamic properties, impact odor-mediated predator-prey interactions in salt marsh communities. I approached this research using an interdisciplinary framework that combined field and laboratory experimentation to address issues of scale and make connections between predator behavior and patterns of predation in the field. I explored a variety of interactions mediated by changes in the sensory landscape including; indirect effects of biotic structure on associated prey, predator responses to patches of prey with differing density and distribution, and dynamic interactions between predators and prey distributions. I found that biotic structure (oyster reefs [Crassostrea virginica]) has negative indirect effects on associated hard clam prey (Mercenaria mercenaria) through the addition of oyster reef odor cues that attract predators (blue crabs [Callinectes sapidus] and knobbed whelks [Busycon carica])and increase foraging success near the structural matrix. Variation in the structure of patch-scale prey odor plumes created by multiple prey results in predator-specific patterns of predation as a function of patch density and distribution which are mediated by differences in predator sensory ability. There is a potential negative feedback loop between blue crab predators and hard clam prey distributions; clam patches assume random within-patch distributions after exposure to blue crab predators, making the detection of patches by future blue crab predators more difficult. Sensory landscapes are also mediated by water flow, which transports prey odor plumes downstream to predators. Characterization of water flow in small-scale estuary systems indicates that values of turbulent flow parameters are highly context specific and depend on both tidal type (spring, neap, normal) and site. Wind and tidal range seem to be good predictors for wave components and turbulent components of fluctuating flow parameters, respectively, although the strength of their predictive ability is dependent on time scale. Modifications of the sensory landscape through changes in structurally-induced turbulence, mixing of individual plumes from multiple prey, and bulk velocity and turbulence characteristics need to be considered when formulating predictions as to the impact of predators on naturally occurring prey populations in the field.

Made available in DSpace on 2016-06-02T19:22:10Z (GMT). No. of bitstreams: 1 Retido.pdf: 19733 bytes, checksum: 6aad255badc436a06364517de2344ab6 (MD5) Previous issue date: 2013-09-06 / Universidade Federal de Minas Gerais / The periaqueductal gray (PAG), a midbrain structure, is directly related to the modulation of survival behaviors and has direct projections to several central nuclei that are involved in breathing control, including the A5 cell group, nucleus of the solitary tract, rostral ventrolateral medulla, raphe nuclei among others. It also receives afferents from areas involved in the control of body temperature such as dorsal medial hypothalamus. Although it is already known that the PAG elicits ventilatory responses when stimulated, the neural circuits involved in this response are not fully elucidated. Therefore, this study explored the involvement of dorsal and ventral PAG on cardiorespiratory and thermal responses to normocapnia, hypercapnia and hypoxia. Thus, ibotenic acid (IBO) or vehicle (PBS, Sham group) was injected into the dPAG (dorsomedial/dorsolateral) or vPAG (lateral/ventrolateral) of male Wistar rats. Pulmonary ventilation (VE), mean arterial pressure (MAP), heart rate (HR) and body temperature (Tb) were measured in unanaesthetized rats during normocapnia normoxic, hypercapnic and hypoxic exposure (5, 15, 30 min, 7% CO2). The first set of experiments with hypercapnic challenge, IBO lesioning of the dPAG caused reduction of 31% of the respiratory response to CO2 (1094.3 ± 115 mL/Kg/min) compared with Sham (1589.5 ± 88.1 mL/Kg/min), whereas lesion of vPAG caused a decrease in 26% of hypercapnic hyperpnoea (1215.3 ± 108.6 mL/Kg/min) compared with Sham (1657.3 ± 173.9 mL/Kg/min). Basal VE, MAP, HR and Tb were not affected by dPAG or vPAG lesion. These results suggest that dPAG and vPAG exert an excitatory modulation of hypercapnic ventilatory response in rats but do not affect MAP, HR or Tb regulation in resting conditions or during hypercapnia. As to hypoxic challenge, lesions of 3.9 e 2.8% of dPAG and vPAG, respectivally, promoted by microinjection of 0.5 μL of IBO in dPAG and vPAG, did not change the cardioventilatory and thermal responses to hypoxia. The increase of the volume of injection of IBO to 1 μL caused 9.8% and 6.7% of dPAG and vPAG lesion, respectivally. Lesion of dPAG increased 67% the hypoxic ventilatory response (1730 ± 282.5 mL/Kg/min) compared to Shamp group (991.4 ± 194 mL/Kg/min), but lesion of vPAG did not change the cardiorespiratory and thermal responses to hypoxia. As observed with 0.5 μL of IBO, the increase of the size of dPAG and vPAG lesion did not affesct MAP, HR and Tb. In conclusion, dPAG neurons exert an inhibitory modulation of hypoxic respiratory. Additionally, the PAG does not appear to exert a tonic role on cardiovascular and thermal parameters during normoxia and hypoxic conditions. / A substância cinzenta periaquedutal (SCP), uma estrutura mesencefálica, está diretamente relacionada com a modulação de comportamentos de sobrevivência e possui projeções diretas para vários núcleos centrais que estão envolvidos no controle respiratório, dentre eles, o grupo celular A5, núcleo do trato solitário, bulbo ventrolateral rostral e núcleo da rafe entre outros. Também recebe aferências do hipotálamo dorso medial, região esta envolvida no controle da temperatura corporal. Embora, já seja conhecido que a SCP elicia respostas cardiorrespiratórias quando estimulada, os mecanismos modulatórios envolvidos ainda não estão totalmente elucidados. Sendo assim, o presente projeto teve como objetivos verificar a participação da SCP dorsal (dorsomedial/dorsolateral) e SCP ventral (lateral/ventrolateral) nas respostas cardiorrespiratórias e termorreguladoras frente à normocapnia normóxica, hipercapnia e hipóxia por meio da lesão química com ácido ibotênico. Assim, ácido ibotênico (IBO 0,5 μL) ou veículo (PBS 0,5 μL; Grupo Sham) foram injetados na SCP dorsal e ventral de ratos Wistar. Ventilação pulmonar (VE), pressão arterial média (PAM), frequência cardíaca (FC) e temperatura corporal (Tc) foram medidas em ratos não anestesiados durante normocapnia, hipercapnia e hipóxia aos 5, 15, 30 min. após exposição (7% CO2 ou 7% O2). A lesão na SCPd causou redução de 31% na resposta respiratória ao CO2 (1094,3 ± 115 mL/Kg/min) comparada ao grupo Sham (1589,5 ± 88,1 mL/Kg/min). Nos animais com lesão da SCPv ocorreu uma redução de 26% na resposta ventilatória ao CO2 (1215,3 ± 108,6 mL/Kg/min) comparada ao grupo Sham (1657,3 ± 173,9 mL/Kg/min). A ventilação basal, PAM, FC e Tc não foram afetadas pelas lesões na SCPd/SCPv. Os resultados sugerem que SCPd e SCPv exercem um papel excitatório na resposta ventilatória à hipercapnia em ratos, mas não afetam a PAM, FC e Tc em condições basais ou durante a hipercapnia. Em relação à hipóxia, lesões de 3,9 e 2,8% da SCPd e SCPv, respectivamente, promovidas pela injeção de 0,5 μL de ácido ibotênico não alteraram os parâmetros cardioventilatórios comparados aos controles. O aumento do volume de injeção de ácido ibotênico para 1 μL, promoveu lesão de 9,8% da SCPd e 6,7% da SCPv. O aumento da área lesada na SCPd promoveu um aumento de 67% (1730 ± 282,5 mL/Kg/min) na resposta ventilatória à hipóxia comparado ao grupo Sham (991,4 ± 194 mL/Kg/min) após 15 minutos de exposição. As lesões na SCPv não promoveram mudanças significativas na ventilação comparado ao controle. A ventilação basal, PAM, FC e Tc também não foram afetadas pelas lesões na SCPd/SCPv independente dos volumes testados. Estes resultados sugerem que apenas SCPd modula a resposta ventilatória exercendo um efeito inibitório durante a hipóxia. Adicionalmente, SCP não afeta a PAM, FC e Tc em condições basais ou durante a hipóxia.

The widely accepted view nowadays is that experiencing odours as rather pleasant or unpleasant is, to a certain degree, shaped on a daily basis through individual experience within one's culture via evaluative conditioning or, rather marginally so, via mere exposure to that certain odour. In other words, humans are not born with any fixed set of olfactory likes or dislikes but rather, they acquire them throughout their lifetime. However, olfactory sensation is not a "pure" percept, as odorant stimuli generally elicit a qualitative percept of an odorant - generated mainly by the olfactory nerve - as well as some degree of chemesthesis - a tactile confound of the odour generated mainly by the trigeminal nerve. The olfactory and trigeminal system exhibit complex interactions at both the peripheral and central level of chemosensory processing, which is also reflected in perceptual characteristics of the final percept, including perceived pleasantness (hedonics). If the olfactory contribution alone does not easily predict neonatal odour hedonics, due to newborns' limited previous exposure to chemosensory inputs, one may hypothesize that together with the strength of the trigeminal contribution they may form a significant factor affecting neonatal appetitive/aversive responses to odours. In the present...

The process of respiration is a pattern of spontaneity and automatic motor control that originate in the brainstem. The mechanism by which the brainstem detects CO2 is termed central CO2 chemoreception (CCR). Since the early 1960’s there have been tremendous efforts placed on identification of central CO2 chemoreceptors (molecules that detect CO2). Even with these efforts, what a central CO2 chemoreceptor looks like remain unknown. To test the hypothesis that inward rectifier K+ (Kir) channels are CO2 sensing molecules in CCR, a series of experiments were carried out. 1) The first question asked was whether the Kir4.1-Kir5.1 channel is expressed in brainstem chemosensitive nuclei. Immunocytochemistry was performed on transverse medullary and pontine sections using antibodies raised against Kir4.1 and Kir5.1. Positive immunoassays for both Kir4.1 and Kir5.1 subunits were found in CO2 chemosensitive neurons. In the LC the Kir4.1 and Kir5.1 were co-expressed with the neurokinin-1 receptor that is the natural receptor for substance P. 2) The second question asked was whether the Kir4.1-Kir5.1 channel is subject to modulation by neurotransmitters critical for respiratory control. My studies demonstrated that indeed the Kir4.1-Kir5.1 channel is subject to modulation by substance P, serotonin and thyrotropin releasing hormone. 3) I performed studies to demonstrate the intracellular signaling system underlying the Kir4.1-Kir5.1 channel modulation by these neurotransmitters. The modulation by all three neurotransmitters was dependent upon the activation of protein kinase C (PKC). The Kir4.1-Kir5.1 but not the Kir4.1 channel was modulated by PKC. Both the Kir4.1 and Kir5.1 subunits can be phosphorylated by PKC in vitro. However, systematic mutational analysis failed to reveal the phosphorylation site. 4) The fourth question asked was whether Kir channels share a common pH gating mechanism that can be identified. Experiments were performed to understand the gating of the Kir6.2+SUR1 channel as specific sites for ligand binding and gating have been demonstrated. I identified a functional gate that was shared by multiple ligands that is Phe168 in the Kir6.2. Other Kir channels appear to share a similar gating mechanism. Taken together, these studies demonstrate the modulation of Kir channels in central CO2 chemoreception.