Influência de fatores individuais e sociais sobre as respostas endócrina e comportamental de callithrix jacchus a desafios ambientais físicos e sociais

Regarding the growing number of human beings with physical and mental pathologies associated to different stressor agents, attempts are being made to validate animal models with a close phylogenetic resemblance to man, to study stress response. Callithrix jacchus has been widely used in biomedical research, including on stress, but there is scarce information in the literature about how individual and social factors modulate stressor response in this species. This study uses 4 approaches to investigate the response of male and female adult C. jacchus, under situations of stress, and in the first we show evidence of the importance of this animal as an experimental model in research involving the hypothalamus-pituitary-adrenal axis. And we investigate if sex and baseline cortisol levels modulate the behavioral and hormonal response to separation. In two additional approaches investigate if type of social support (co-specific parent or non-parent) and social rank interfere in behavioral and hormonal when the animal are exposure to a new environment, paired with a co-specific (F2), exposure of the animal to a new environment, isolated (F3) or during reunion (F4). Finally, we also investigated the androgen levels in the males, with a focus on the challenge hypothesis, referring to environmental responsiveness and male-male exposure to relatives and non-relatives of C. jacchus. It was observed that: (1) the baseline cortisol of the animal is predictive of cortisol reactivity at separation; (2) males and females do not show dimorphism in the response of cortisol to stressors, although the females have higher baseline levels of this hormone and exhibit higher frequencies of anxiety-related behaviors; (3) only social support provided by relatives proved to be effective in buffering the cortisol response. In behavioral terms this response was dimorphic, showing that only the male dyads displayed an attenuated response to stress; (4) the males showed differences in cortisol levels as a function of social rank and study phases, whereas in the females no such alterations were observed. The males with indefinite dominance hierarchy (IDH) had reduced cortisol in F2 and F4, while the IDH females showed an increase in F3 and F4; (5) the males of relative and non-relative dyads did not exhibit variations in androgen levels as a function of a new environment. These results, taken together, (a) corroborate the use of C. jacchus as a good animal model for stress-related studies, given that they exhibit similar behavioral and physiological alterations to those of human beings in response to stressor agents; (b) point to the importance of considering individual and social modulating factors during experiments with stressors; (c) provide more reliable comparison parameters in studies where these primates are used as animal models, and (d) show that androgens vary as a function of genetic proximity (relative or non-relative) when the animals are faced with physical and social environmental challenges, thus providing important information for studying the challenge hypothesis in this species

Diferenças funcionais das regiões hipocampais na formação da memória do tipo o quê", "quando" e "onde" em ratos

Episodic memory refers to the recollection of what, where and when a specific event occurred. Hippocampus is a key structure in this type of memory. Computational models suggest that the dentate gyrus (DG) and the CA3 hippocampal subregions are involved in pattern separation and the rapid acquisition of episodic memories, while CA1 is involved in memory consolidation. However there are few studies with animal models that access simultaneously the aspects ‗what-where-when . Recently, an object recognition episodic-like memory task in rodents was proposed. This task consists of two sample trials and a test phase. In sample trial one, the rat is exposed to four copies of an object. In sample trial two, one hour later, the rat is exposed to four copies of a different object. In the test phase, 1 h later, two copies of each of the objects previously used are presented. One copy of the object used in sample trial one is located in a different place, and therefore it is expected to be the most explored object.However, the short retention delay of the task narrows its applications. This study verifies if this task can be evoked after 24h and whether the pharmacological inactivation of the DG/CA3 and CA1 subregions could differentially impair the acquisition of the task described. Validation of the task with a longer interval (24h) was accomplished (animals showed spatiotemporal object discrimination and scopolamine (1 mg/kg, ip) injected pos-training impaired performance). Afterwards, the GABA agonist muscimol, (0,250 μg/μl; volume = 0,5 μl) or saline were injected in the hippocampal subregions fifteen minutes before training. Pre-training inactivation of the DG/CA3 subregions impaired the spatial discrimination of the objects (‗where ), while the temporal discrimination (‗when ) was preserved. Rats treated with muscimol in the CA1 subregion explored all the objects equally well, irrespective of place or presentation time. Our results corroborate the computational models that postulate a role for DG/CA3 in spatial pattern separation, and a role for CA1 in the consolidation process of different mnemonic episodes

Administração repetida de baixas doses de reserpina: um possível modelo para o estudo de déficits cognitivos e motores associados à Doença de Parkinson

Parkinson's disease (PD) is one of the most common neurodegenerative brain disorders and is characterized primarily by a progressive degeneration of dopaminergic neurons nigroestriatais. The main symptoms of this disease are motor alterations (bradykinesia, rigidity, tremor at rest), which can be highly disabling in advanced stages of the condition. However, there are symptomatic manifestations other than motor impairment, such as changes in cognition, mood and sensory systems. Animal models that attempt to mimic clinical features of PD have been used to understand the behavioral and neural mechanisms underlying neurophysiological disturbance of this disease. However, most models promote an intense and immediate motor impairment, consistent with advanced stages of the disease, invalidating these studies for the evaluation of its progressive nature. The administration of reserpine (a monoamine depletor) in rodents has been considered an animal model for studying PD. Recently we found that reserpine (in doses lower than those usually employed to produce the motor symptoms) promotes a memory deficit in an aversive discrimination task, without changing the motor activity. It was suggested that the administration of this drug in low doses can be useful for the study of memory deficits found in PD. Corroborating this data, in another study, acute subcutaneous administration of reserpine, while preserving motor function, led to changes in emotional context-related (but not neutral) memory tasks. The goal of this research was to study the cognitive and motor deficits in rats repeatedly treated with low doses of reserpine, as a possible model that simulates the progressive nature of the PD. For this purpose, 5-month-old male Wistar rats were submitted to a repeated treatment with vehicle or different doses of reserpine on alternate days. Cognitive and motor parameters and possible changes in neuronal function were evaluated during treatment. The main findings were: repeated administration of 0.1 mg / kg of reserpine in rats is able to induce the gradual appearance of motor signs compatible with progressive features found in patients with PD; an increase in striatal levels of oxidative stress and changes in the concentrations of glutamate in the striatum were observed five days after the end of treatment; in animals repeatedly-treated with 0. 1 mg/kg, cognitive deficits were observed only after the onset of motor symptoms, but not prior to the onset of these symptoms; 0.2 mg / kg reserpine repeated treatment has jeopardized the cognitive assessment due to the presence of severe motor deficits. Thus, we suggest that the protocol of treatment with reserpine used in this work is a viable alternative for studies of the progressive appearance of parkinsonian signs in rats, especially concerning motor symptoms. As for the cognitive symptoms, we suggest that more studies are needed, possibly using other behavioral models, and / or changing the treatment regimen

Caracterização comportamental endócrina das fases ontogenéticas de sagüi comum (Callithrix jacchus)

The use of animal models in biomedical research is ever increasing. Models that use primates might also have advantages in terms of low maintenance costs and availability of biological knowledge, thereby favoring their use in different experimental protocols. Many current stress studies use animal models at different developmental stages since biological response differs during ontogeny. The aims of this study were to perform a detailed characterization of the developmental stages of common marmosets (Callithrix jacchus), a very important animal model used in biomedical research. Ten subjects, 6 females and 4 males, were followed from birth to initial adult age (16 months). Behavioral and fecal collection for measurement of adrenal (cortisol) and sex (progesterone, estradiol and androgens) hormones took place twice a week during the first month of life and once a week for the remainder of the study. Behavior was observed for 30 minutes in the morning (0700-09:00h) and afternoon (12:00-14:00h). Behavioral profile showed changes during ontogeny, characterizing the 4 developmental stages and the respective phases proposed by Leão et al (2009).. Differentiation of developmental stages was considered using the onset, end, change and stabilization of the behavioral profile parental care (weaning and carrying), ingestion (solid food), affiliation (social grooming) and autogrooming, agonism (scent marking and piloerection) and play behavior and endocrine profile. Infant weaning and carrying terminated within the infantile stage and the peak of solid food ingestion was recorded in the infantile III phase. Receiving grooming was recorded earlier than grooming performed by the infant and autogrooming. The first episode of scent marking was recorded in the 4th week and it was the least variable behavior, in terms of its onset, which, in almost all animals, was between the 5th and 7th week of life. Solitary play and play with the twin started around the 7th week and play with other members of the group started 8 weeks later. Sex hormone secretion started to differ from basal levels between the 21st and 23rd week of life, in males and females, suggesting that puberty occurs simultaneously in both sexes. Basal cortisol, even at an early age, was higher in females than in males. However, cortisol was not correlated with the juvenile stage, as expected, since this stage corresponds to the transition between infancy and adult age and most behaviors are intensified by this time. The behavioral and endocrine profile of subadult animals did not differ from that of the adults. These results provide more detailed parameters for the developmental process of C. jacchus and open new perspectives for the use of experimental approaches focused on the intermediate ontogenetic phases of this species

Estudo da organização funcional do sistema circadiano por meio de ferramentas computacionais e matemáticas

Circadian rhythms are variations in physiological processes that help living beings to adapt to environmental cycles. These rhythms are generated and are synchronized to the dark light cycle through the suprachiasmatic nucleus. The integrity of circadian rhythmicity has great implication on human health. Currently it is known that disturbances in circadian rhythms are related to some problems of today such as obesity, propensity for certain types of cancer and mental disorders for example. The circadian rhythmicity can be studied through experiments with animal models and in humans directly. In this work we use computational models to gather experimental results from the literature and explain the results of our laboratory. Another focus of this study was to analyze data rhythms of activity and rest obtained experimentally. Here we made a review on the use of variables used to analyze these data and finally propose an update on how to calculate these variables. Our models were able to reproduce the main experimental results in the literature and provided explanations for the results of experiments performed in our laboratory. The new variables used to analyze the rhythm of activity and rest in humans were more efficient to describe the fragmentation and synchronization of this rhythm. Therefore, the work contributed improving existing tools for the study of circadian rhythms in mammals

Influência do ciclo estral no efeito do diazepam na ansiedade e memória de ratas

Memory and anxiety are related phenomena. Several evidences suggest that anxiety is fundamental for learnining and may facilitate or impair the memory formation process depending of the context. The majority of animal studies of anxiety and fear use only males as experimental subjects, while studies with females are rare in the literature. However, the prevalence in phobic and anxiety disorders is greater in women than in men. Moreover, it is known that gender maybe influence benzodiazepine effects, the classic drugs used for anxiety disorders treatment. In this respect, to further investigate if fear/anxiety aspects related to learning in female subjects would contribute to the study of phobic and anxiety disorders and their relationship with learning/memory processes, the present work investigates (a) the effects of benzodiazepine diazepam on female rats performance in a aversive memory task that assess concomitantly anxiety/emotionality, as the interaction between both; (b) the influence of estrous cycle phases of female rats on diazepam effects at aversive memory and anxiety/emotionality, and the interaction between both and (c) the role of hormonal fluctuations during estrous cycle phases in absence of diazepam effects in proestrus, because female rats in this phase received or not mifepristone, the antagonist of progesterone receptor, previously to the diazepam treatment. For this purpose, the plus maze discriminative avoidance task, previously validated for studies of anxiety concomitantly to learning/memory, was used. The apparatus employed is an adaptation of a conventional plus maze, with two opens arms and two closed arms, one of which presenting aversive stimulation (noise and light). The parameters used were: time in non-aversive arm compared to time in aversive and percentage of time in aversive arm on several temporal divisions, in order to evaluate memory; percentage of time in open arms, risk assessment, head dipping and end exploring to evaluate anxiety ; and distance traveled for locomotion. In experiment I, we found anxiolytic effect of diazepam only for 4 mg/kg dose, however the amnestic effect appear at a dose of 2 mg/kg. In second experiment, rats were divided in groups according estrous cycle phase (metaestrus/diestrus, proestrus e estrus). In this experiment, when we considered estrous cycle phase or diazepam treatment, the results did not demonstrate any differences in anxiety/emotionality parameters. The amnestic effects of diazepam occur in female rats in metestrus/diestrus and estrus and is absent in proestrous rats. Proestrous female rats that received mifepristone exhibited the amnestic effect of diazepam and also anxiolytic effects, that it was not previously observed in this dose. The results have demonstrated dissociation of anxiolytic and amnestic diazepam effects, not previously observed in males; the absence of amnestic effect of diazepam in proestrous phase; and the possible role of progesterone in aversive memory over diazepam effect, because the mifepristone, associated with diazepam, caused amnestic effect in proestrus

Efeitos da estimulação ambiental sobre os aspectos motores, cognitivos e neuronais em um modelo farmacológico progressivo da doença de Parkinson

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Efeitos de diferentes tipos estressores sobre a memória e aprendizagem de ratas

The exposure to stressors produces physiological changes of the organism in order to adapt the individual to the environment. Depending on the type, intensity and duration, stress can affect some cognitive functions, particularly processes of learning and memory. Several studies have also proposed that some level of anxiety would be necessary for memory formation. In this context, memories of previously aversive experiences may determine the manner and intensity with which are expressed fear responses, which explains the great interest in analyzing both anxiety and memory in animals. In addition, males and females demonstrate different reactions in relation to stressful stimuli, showing different levels of anxiety and differences in processing of the acquisition, retention and recall of information. Based on this information, the present study aimed to verify the effect of stress on learning, memory and anxiety behavioral parameters in rats exposed at different types of stressors of long duration (seven consecutive days): restraint (4h/day), overcrowding (18h/day) and social isolation (18h/day) in the different phases of the estrous cycle. Our results showed that the stress induced by restraint and social isolation did not cause changes in the acquisition process, but impaired the recall of memory in rats. Furthermore, it is suggested a protective effect of sex hormones on retrieval of aversive memory, since female rats in proestrus or estrus phase, characterized by high estrogen concentrations, showed no aversive memory deficits. Furthermore, despite the increased plasma levels of corticosterone observed in female rats subjected to restraint stress and social isolation, anxiety levels were unaltered, compared to those various stress conditions. Animal models based on psychological and social stress have been extensively discussed in the literature. Correlate behavioral responses, physiological and psychological have contributed in increasing the understanding of stress-induced psychophysiological disorders

Curva de aprendizado em cirurgia aórtica videolaparoscópica: estudo experimental em porcos

CONTEXTO: A cirurgia videolaparoscópica (CVL) vem evoluindo como alternativa cirúrgica menos invasiva para o tratamento da doença aterosclerótica oclusiva aorto-ilíaca e do aneurisma da aorta abdominal. Poucos estudos avaliaram objetivamente a curva de aprendizado com essa técnica em cirurgia vascular. OBJETIVO: Avaliar objetivamente os tempos e a evolução de cada passo cirúrgico e demonstrar a exeqüibilidade dessa técnica. MÉTODOS: Entre outubro 2007 e janeiro de 2008, dois cirurgiões vasculares iniciantes na CVL operaram, após cursos e treinamentos, seis porcos consecutivos, com dissecção aórtica e interposição de um enxerto de dácron em um segmento da aorta infra-renal abdominal, com técnica totalmente laparoscópica. RESULTADOS: Todos os tempos cirúrgicos foram decrescentes ao longo do estudo, apresentando redução de 45,9% no tempo total de cirurgia, 85,8% no tempo de dissecção da aorta, 81,2% na exposição da aorta, 55,1% no clampeamento total, 71% na confecção da anastomose proximal e 64,9% na anastomose distal. CONCLUSÃO: O presente estudo mostrou que os resultados técnicos satisfatórios da CVL vascular ocorreram somente após longa curva de aprendizado, que foi decrescente ao longo do tempo, à medida que aumentou a experiência e vivência com os materiais e com a visão não-estereoscópica. Essa técnica pode ser realizada com perfeição por cirurgiões vasculares desde que façam cursos especializados, com treinamento em simuladores e animais, e desde que busquem constante aprimoramento a fim de conseguir resultados similares aos obtidos com a cirurgia convencional.

Uso precoce e tardio de dopamina após isquemia miocárdica

OBJETIVO: Avaliar os efeitos na função ventricular esquerda do uso precoce e tardio de dopamina, em modelo experimental de coração isolado. MÉTODO: Foram utilizados 60 coelhos em modelo de coração isolado mantido por animal suporte. Um balão intraventricular foi locado no ventrículo esquerdo. Três grupos foram constituídos: grupo controle (GC); grupo que recebeu dopamina precoce (Dopa P) e grupo que recebeu dopamina tardia (após 20 minutos) (Dopa T). Foram realizadas leituras hemodinâmicas diretas e indiretas. RESULTADOS: Fluxo sangüíneo coronariano: GC(7,196 ± 1,275ml/min); Dopa P (9,477 ± 1,160ml/min); Dopa T (14,316 ± 2,308ml/min), com GC=Dopa P, GC ¹Dopa T e Dopa P¹Dopa T. Primeira derivada temporal da pressão intraventricular (dp/dt+): GC (719,61 ± 127,53ml/min); Dopa P (719,61 ± 127,53ml/min); Dopa T (1431,60 ± 230,87ml/min), p<0,05, Dopa P¹Dopa T, GC=Dopa P e GC ¹ Dopa T. Primeira derivada temporal da pressão intraventricular negativa (dp/dt-): GC (469,85 ± 107,16mmHg/s); Dopa P (716,07 ± 215,66mmHg/s); Dopa T (931,24 ± 181,46mmHg/s), p<0,05, Dopa P¹Dopa T¹GC. Delta V: GC (1,355 ± 0,2432ml); Dopa P (0,97 ± 0,3199ml); Dopa T (1,27 ± 0,2983ml), p>0,05, Dopa P=Dopa T=GC. Estresse sistólico desenvolvido: GC (27,273 ± 10,276g/cm²); Dopa P (55,219 ± 24,625g/cm²); Dopa T (79,152 ± 12,166g/cm²), Dopa P=Dopa T, Dopa P=GC e GC ¹ Dopa T.Dialdeído Malônico (MDA): GC (4,5 ± 0,527mmol/L); Dopa P (4,7 ± 1,16mmol/L); Dopa T (4,1 ± 0,7379mmol/L), p>0,05, Dopa P=Dopa T=GC. CONCLUSÕES: Concluiu-se que, no modelo experimental delineado, o uso precoce da dopamina foi deletério, segundo algumas variáveis hemodinâmicas.

Effects of hypertension on maternal adaptations to pregnancy: experimental study on spontaneously hypertensive rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Experimental models of autoimmune inflammatory ocular diseases

A inflamação ocular é uma das principais causas de perda visual e cegueira. As uveítes constituem um grupo complexo e heterogêneo de doenças caracterizadas por inflamação dos tecidos intraoculares. O olho pode ser o único órgão envolvido ou a uveíte pode ser parte de uma doença sistêmica. A etiologia é desconhecida em um número significativo de casos, que são considerados idiopáticos. Modelos animais têm sido desenvolvidos para estudar a fisiopatogênese da uveíte autoimune devido às dificuldades na obtenção de tecidos de olhos humanos inflamados para experimentos. Na maioria desses modelos, que simulam as uveítes autoimunes em humanos, a uveíte é induzida com proteínas específicas de fotorreceptores (antígeno-S, proteína ligadora de retinoide do interfotoreceptor, rodopsina, recoverina e fosducina). Antígenos não retinianos, como proteínas associadas à melanina e proteína básica de mielina, são também bons indutores de uveíte em animais. Entender os mecanismos básicos e a patogênese dessas doenças oculares é essencial para o desenvolvimento de novas formas de tratamento das uveítes autoimunes e de novos agentes terapêuticos. Nesta revisão serão abordados os principais modelos experimentais utilizados para o estudo de doenças inflamatórias oculares autoimunes.

Clinical evaluation and induced corneal vascularization study by native and anionic collagen membranes in rabbits corneas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Papel do exercício físico na isquemia/reperfusão pulmonar e resposta inflamatória

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Terapia celular em doenças pulmonares: existem perspectivas?

A terapia celular poderia ser conceituada de forma ampla e genérica como o emprego de células para tratamento de doenças. Apesar de um número não tão expressivo de relatos tendo o pulmão como objeto de estudo na terapia celular em pacientes humanos, há dados consistentes da literatura, tanto em humanos, quanto em modelos animais,que evidenciam a migração de células-tronco da medula óssea para o pulmão,em diferentes situações experimentais. Esses resultados forneceram o embasamento experimental para o emprego de células-tronco na regeneração do tecido pulmonar em modelos animais. em nosso laboratório, vários projetos de pesquisa têm sido conduzidos com a finalidade de avaliar a resposta pulmonar (morfológica e funcional) ao tratamento com células-tronco adultas em camundongos com doença pulmonar obstrutiva crônica (DPOC) induzida experimentalmente. Os resultados obtidos, aliados àqueles de outros grupos de pesquisa, permitem aventar a possibilidade de aplicação, a curto prazo, da terapia celular em pacientes com DPOC. em outra patologia pulmonar, fibrose cística (FC), cuja abordagem terapêutica com células-tronco apresenta aspectos particulares em relação às patologias pulmonares crônico-degenerativas, há avanços promissores e potencialmente interessantes; no entanto, os resultados podem ser considerados incipientes e deve-se assinalar, portanto, que a associação da terapia gênica e celular apresenta-se como uma alternativa possível, mas ainda muito distante quanto à sua consolidação e incorporação como opção terapêutica segura e eficaz em FC. Por outro lado, tendo por embasamento os resultados obtidos em modelos experimentais, é possível postular que a terapia celular com células-tronco hematopoéticas (ou de outras fontes) encerra perspectivas consistentes de aplicação em diversas outras patologias pulmonares humanas, especialmente em DPOC.