O objetivo do presente trabalho foi investigar as repercussões de uma relação social estável sobre diferentes parâmetros de comportamento, neuroquímica e atividade imune de camundongos dominantes e submissos. Machos adultos (com aproximadamente 90 dias de idade) mantidos em duplas desde o desmame, foram determinados como dominantes ou submissos, após três avaliações consecutivas do comportamento, onde foram observadas a presença ou ausência de ataques ou fugas e posturas de submissão. Em alguns experimentos, grupos de cinco animais mantidos em uma mesma caixa foram utilizados para comparação com resultados obtidos de animais que conviveram em duplas. Foram utilizadas apenas as duplas de camundongos onde a hierarquia social foi claramente observada. Os resultados mostraram que os animais submissos apresentaram em relação aos dominantes: 1) diminuição no tempo gasto na zona central do campo aberto; 2) diminuição no número de entradas nos braços abertos e diminuição no tempo gasto na exploração dos braços abertos do labirinto em cruz elevado; 3) aumento no tempo gasto na exploração dos braços fechados do labirinto em cruz elevado; 4) diminuição no número de entradas e no tempo gasto na exploração do terço final dos braços fechados do labirinto em cruz elevado; 5) aumento na taxa de renovação de dopamina no hipotálamo; 6) diminuição da taxa de renovação de dopamina no corpo estriado; 7) maior número de metástases induzidas pelo melanoma murino experimental B16F10; 8) aumento do percentual de células T CD8+ no timo após 14 dias de inoculação do mesmo melanoma; 9) diminuição no burst oxidativo basal de neutrófilos e monócitos sangüíneos, mas não naquele induzido por bactérias; 10) menor atividade de células NK presentes no baço e no sangue. Em relação aos animais mantidos em número de cinco, os animais submissos apresentaram: menor percentual de células NK no sangue. Já os animais dominantes, apresentaram em relação aos animais mantidos em grupos: 1) aumento da taxa de renovação de noradrenalina no hipotálamo; 2) aumento na taxa de renovação de dopamina no corpo estriado; 3) menor percentual de células NK no sangue. O status social, no entanto, não provocou diferenças: 1) nos níveis absolutos de dopamina, noradrenalina e serotonina; 2); nos metabólitos de serotonina; 3) nos níveis séricos basais de corticosterona; 4) no peso e número de células do baço e timo; 5) no percentual de células T CD4+ e CD8+ no baço e 6) no percentual de linfócitos, neutrófilos e monócitos sangüíneos. Em conjunto, os presentes resultados mostraram que animais dominantes e submissos mantidos por 90 dias em uma hierarquia social estável, apresentaram diferenças comportamentais e neuroquímicas, e responderam de forma diferente a um mesmo estímulo imune, no caso, o desenvolvimento de metástases induzida nos pulmões pela administração do melanoma experimental murino B16F10. Estes resultados sugerem que diferentes mecanismos, que não a ativação do eixo HPA, estejam envolvidos com o aumento de susceptibilidade ao desenvolvimento do tumor observado nos indivíduos submissos / The objective of the present work was to investigate the repercussions of a stable social relationship on different parameters of the behavior, neurochemical and immune activity of dominant and submissives mice. Adult males (with approximately 90 days of age) kept in pairs since wean it, had been determined as dominant or submissives, after three consecutive evaluations of the behavior, where presences or absences of attacks or escapes and positions of submission had been observed. In some experiments, groups of five animals kept in one same box had been used to compare the results gotten between these and the animals coexisting in pairs. The pairs had been used only where the social hierarchy clearly was observed. The results had shown that the submissives animals in relation to the dominant ones had presented: 1) reduction in the time spent in the central zone of the open field; 2) reduction in the number of entrances in the open arms and reduction in the time spent in the exploration of the open arms of the plus maze; 3) increase in the time spent in the exploration of the closed arms of the plus maze; 4) reduction in the number of entrances and time spent in the exploration of the final third of the closed arms of the plus maze; 5) increase in the turnover of dopamine in the hypothalamus; 6) reduction in the turnover of dopamine in the corpus striatum; 7) increased number of metastasis in the lungs induced by murino melanoma experimental B16F10; 8) increase of the percentage of cells T CD8+ in the thymus after 14 days of inoculation of the same melanoma; 9) reduction in the basal oxidative burst of neutrophil and monocytes sanguine, but not in the induced by bacteria; 10) decreased NK cells activity measured in the blood and spleen. In relation to the animals kept in number of five, the submissives animals had presented: 11) reduction in the percentile of NK cells in the blood. While the dominant animals had presented in relation to the animals kept in groups: 1) increase in the turnover of norepinephrine in hypothalamus; 2) increase in the turnover of dopamine in the fluted body; 3) reduction in the percentile of NK cells in the blood. The social status, however, did not provoke differences: 1) in the absolute levels of dopamine, norepinephrine and serotonin; 2) in the metabolites of serotonin; 3) in the serum levels of corticosterone; 4) in the weight and number of cells of the spleen and thymus; 5) in the percentage of cells T CD4+ and CD8+ in the spleen and 6) in the percentage of lymphocytes, neutrophil and monocytes in the blood. Together, the results obtained had shown that dominants and submissives animals kept 90 days living in a stable social hierarchy had presented behavior and neurochemical differences, and had answered of different form to one same immune stimulation, in this case, the induced development of metastasis in the lungs for experimental melanoma murino B16F10, where the submissives had been more susceptible than the dominant ones. This results suggest that other mechanisms, different of HPA activation, may be involved with the decreased resistance of submissive mice to B16F10 tumor dissemination

Implantation of dental sponges under the skin of lab rodents has been used to evaluate whether acute stress enhances leukocyte infiltration to a surgical site. First, I replicated this technique in house sparrows to test whether transient stressors cause similar immunoredistribution (i.e., movement of immune cells out of circulation and to the periphery) in a wild animal. As placement into captivity alone may serve as a stressor to wild animals, I compared sponge infiltration over different periods of captivity. Second, I compared how domestication affects immunoredistribution by comparing results of wild sparrows to domesticated zebra finches. Zebra finches were chosen because they are widely used for evolutionary ecology research, and they share a similar diet and comparable body size and lifestyle to house sparrows. Birds were randomly assigned to treatment groups of either a restraint stressor or no restraint stressor treatment prior to implantation. In the first chapter birds were also divided into one of three groups: sponge implantation at capture, after short duration captivity (1 or 2 days), or long duration captivity (1 month). Total leukocyte infiltration into the sponge varied among captive groups. Birds implanted at capture had greater leukocyte infiltration to the sponge compared to birds kept in captivity 1 or 2 days before implantation. Birds placed into captivity for 1 month before implantation showed similar sponge infiltration relative to the immediate implant group. However, time in captivity altered the dominant type of leukocytes present in the sponge at explant with lymphocytes decreasing with time in captivity and granulocytes increasing. Domestication affected cell infiltrates with domesticated species exhibiting more infiltration of heterophils and monocytes while wild house sparrows exhibited more infiltration of lymphocytes and basophils. My data indicates that in house sparrows, time in captivity affects the magnitude and character of immune responses to surgery and more importantly data are suggestive of immunoredistribution. My data also indicate that domestication has an impact on infiltrating cell types.

The effects of constant food deprivation, terminated at different times of day were examined with respect to percent body weight loss (%BWL), plasma corticosterone (PC) and plasma glucose (PG). A 19-hour food deprivation paradigm schedule staggered around varying times of the day-night cycle was used. Patterns of %BWL related to nocturnal lipogenesis and diurnal lipolysis showed the greatest loss (10%) occurring at 0700 hr, while in evening hours, there was an increasing pattern of weight loss, with the greatest amount (7%) occurring at 2200 hr. A pattern suggestive of neuroregulatory cycles of glucocorticoid release was evident for PC levels; maximum levels for PC (23.2 μg%) were reported at 0700 hr and at 1900 hr (16.6 μg%). Similar patterns were also noted in PG levels, with respective maximum levels of 138.0 mg% and 125.8 mg% occurring at 0700 hr and 1900 hr. These results indicate that the time of day that a deprivation schedule is initiated and terminated is an important consideration due to the impact of circadian photoperiodism. Time of day should be an essential consideration when utilizing deprivation paradigms.

Stress can enhance or suppress immune functions depending on a variety of factors. Our previous studies observed that Toll-like receptor 2 (TLR2) participates in chronic restraint stress-induced immune dysfunction. However, the mechanism by which TLR2 prevents immune suppression remains elusive. Our investigation found that stimulation of TLR2 by peptidoglycan (PGN) significantly attenuates splenocyte apoptosis and markedly blocks alterations of anti-apoptotic and apoptotic proteins. Activation of TLR2 inhibits chronic stress-reduced phosphorylation of c-Jun N-terminal kinase (JNK) and diminishes chronic stress-induced up-regulation of corticosterone production. Additionally, our data show that chronic stress causes a dramatic decrease of cytokine IL-2 level but an increase of IL-4 and IL-17 in CD4+ T cells. Interestingly, PGN could block these alterations of cytokine levels. Collectively, our studies demonstrate that stimulation of TLR2 attenuates chronic stress-induced immune suppression by modulating apoptosis-related proteins and immunoregulatory agents.

Stress can enhance or suppress immune functions depending on a variety of factors. Our previous studies observed that Toll-like receptor 2 (TLR2) participates in chronic restraint stress-induced immune dysfunction. However, the mechanism by which TLR2 prevents immune suppression remains elusive. Our investigation found that stimulation of TLR2 by peptidoglycan (PGN) significantly attenuates splenocyte apoptosis and markedly blocks alterations of anti-apoptotic and apoptotic proteins. Activation of TLR2 inhibits chronic stress-reduced phosphorylation of c-Jun N-terminal kinase (JNK) and diminishes chronic stress-induced up-regulation of corticosterone production. Additionally, our data show that chronic stress causes a dramatic decrease of cytokine IL-2 level but an increase of IL-4 and IL-17 in CD4+ T cells. Interestingly, PGN could block these alterations of cytokine levels. Collectively, our studies demonstrate that stimulation of TLR2 attenuates chronic stress-induced immune suppression by modulating apoptosis-related proteins and immunoregulatory agents.

Mechanisms of how red-sided garter snakes (Thamnophis sirtalis parietalis) travel up to 18 km from summer feeding sites to hibernation dens are not understood. In this study, monthly and seasonal trailing behavior were investigated to determine whether red-sided garter snakes prefer to follow trails of snakes from the same den (den-mates) versus trails made by other conspecifics (non-den-mates). Snakes from five different hibernacula in Manitoba, Canada, were involved in the study. Eighteen were adults and 15 were subadults. Subadult red-sided garter snakes do not return to hibernacula until their second year of life, so their trailing behavior was of interest in learning how they might first find hibernation sites.

No description available.

Intravenous admixtures consisting of one or more drug formulations, diluted in a large volume of intravenous solution, are used extensively in current medical practice. Development of reliable methods to predict the compatibility of the admixture components is essential as a guide for their selection. Because the majority of the reports published, to date, have used a visible change as the criterion for judging compatibility, it was the purpose of this study to demonstrate the use of spectrophotometric analysis to detect the occurrence of chemical interactions between two components of an intravenous admixture.

Human activities and unpredictable changes to environmental habitats impose a suite of stress and challenges to animal homeostatic function. Stress responses are often controlled by the release of glucocorticoids to mobilize energy, primarily corticosterone in small mammals, to help regulate homeostatic function such as heterothermy and changes to body condition, the latter of which serves as a proxy for energy reserves. Adaptive heterothermy is influenced by daily and seasonal patterns, heat produced from daily activity, and has been shown to increase in small mammals during times of environmental stress to conserve energy budgets. Body condition also changes in response to environmental perturbations, mobilization of energy by corticosterone, seasonal changes, and activity. My study aimed to disentangle the effects of environment and activity on homeostatic responses by pharmacologically manipulating corticosterone in kangaroo rats. Kangaroo rats are ecosystem engineers, heterothermic, and their activity periods are functions of their thermoregulatory patterns as well as environmental conditions thus making the species a great candidate for this form of study. I conducted two in-situ field experiments to assess for the effects of stress responses on thermoregulation, activity, and body condition. In my first experiment, I used body temperature (Tb) as a proxy for activity time and examined how pharmacologically increased corticosterone influenced kangaroo rat heterothermy responses to the moon phases and ambient temperatures. I also examined their fat, lean mass, and water content at the end of the study. Moon phase was a significant predictor of activity period as animals typically waited longer during the waxing moon phase to become active and cooled down below activity earlier in the night during the waning moon phase. As nights shortened, activity decreased despite environmental conditions becoming warmer. Corticosterone also significantly decreased total activity time and thus steadily increased heterothermy across the length of my experiment. These results indicate activity, not environment, are stronger drivers of heterothermy patterns. Total fat content (energy content) at the end of the study was not affected by corticosterone. The lack of change in fat content was presumably because kangaroo rat body condition was measured once at the end of the study and likely not a reflection of changed body condition over time. In my second experiment, I examined body condition across a longer period by measuring lean mass, fat content, and total body water across a 2-month period in the summer by pharmacologically increasing corticosterone to test the relationship between stress and body condition and to dissociate the two from environmental factors. Body condition indices generally increased across the summer, but corticosterone implantation did not significantly affect body any of the indices. The loss of heterothermic control and decrease in activity time across the summer suggests that animals are likely conserving energy budgets leading to preservation of condition. Further, banner-tailed kangaroo rats generally breed in the spring where body condition falls due to stress induced by increased competition and then increases across the summer as late summer monsoons promote the growth of primary resources utilized by animals thereby preserving body condition. This study suggests that body condition is driven more by life-history traits, activity time, and environment rather than stress responses.

No description available.