The sexes have different life histories that can influence their parental care strategies. I studied northern flicker, Colaptes auratus, parents and simultaneously radio-tracked mates during the nestling and post-fledging periods. I tested hypotheses about sex differences in parental care strategies by examining foraging patterns, provisioning effort and habitat use. Males and females used the same microhabitats, but avoided overlap of their foraging areas on the home range consistent with the hypothesis that mates separate the home range to reduce competition. During temporary (i.e., 24 hr) brood size manipulations, both parents decreased provisioning to reduced broods, but did not increase provisioning to enlarged broods or alter their foraging pattern on the landscape. I suggest flickers were energy limited and were incapable or unwilling to respond to increased brood demands. During the post-fledging period, males spent more time near their fledglings, and cared for their fledglings longer than females (16 days versus 12 days, respectively). Approximately 36% of females abandoned their brood in the post-fledging period and females with high levels of feather corticosterone were more likely to abandon. Older males and those with high provisioning rates in the nestling period fed their fledglings longer. Nearly 45% of fledglings died within the first week after leaving the nest, but survival was higher for fledglings with intermediate body mass and those that occupied areas of dense cover. Families moved a greater distance from the nest during the first 4 days post-fledging when there was less tree cover within 250 m of the nest site. Parents brought fledglings to areas with dense vegetation within the first week post-fledging, but subsequently shifted to open grassland habitats. My results show that parents invest in their offspring indirectly by taking them to habitats that increase survival. This research stresses the importance of studying parental care during the post-fledging period to gain a more complete understanding of the total parental investment of males versus females and how each sex may react differently to trade-offs between investing in the current brood versus self-maintenance.

Prior work has shown important effects of the early life environment on development of adult stress response systems in both rats and humans. The present thesis is based on experiments that attempt to explore: 1) adolescent stress responding at hormonal and behavioural levels, and 2) the effects of repeated adolescent stressor exposure on adult stress responding (hormonal and behavioural) and levels of dopamine receptors expressed in prefrontal cortex, using both male and female rats. Defensive behaviours exhibited during stressor exposure and post-stress levels of circulating corticosterone were quantified as behavioural and hormonal measures of stress responding, respectively. In the first study, responses were compared among groups of adolescent rats exposed repeatedly to one of two different types of cat odour stressor stimuli (J-cloth coated in hair/dander or cat collar previously worn by a cat) or control stimuli, and long-term outcomes were examined in adulthood. Adolescent rats showed behavioural responses to both stressor stimuli, but behavioural inhibition was more consistent using repeated cat collar exposure, and this treatment resulted in long-term increases in anxiety-like behaviour in adulthood, whereas a stress-induced adolescent corticosterone elevation was observed only in the group that received exposure to the J-cloth stimuli. In the second study, adolescent and adult rats were compared directly using repeated exposure to the cat collar stressor or control stimuli. Adolescents were found to be more sensitive to the effects of the stressor stimuli, relative to adults. Finally, in the third study, repeated exposure to the J-cloth stressor or control stimuli was used, and stressor-exposed females showed elevated baseline corticosterone levels prior to the final exposure. Furthermore, stressor-exposed males and females showed lower levels of the D2 dopamine receptor in infralimbic and dorsopeduncular cortices of the prefrontal cortex in adulthood. In addition, these studies together provide evidence that sex differences in corticosterone levels emerge during the adolescent period. It may be concluded that adolescence should be considered a sensitive developmental timeframe for stress response programming.

Chronic ethanol (EtOH) exposure produces neuroadaptations within the NMDA receptor system and alterations in HPA axis functioning that contribute to neurodegeneration during ethanol withdrawal (EWD). Chronic EtOH exposure and EWD, as well as corticosteroids, also promote increased synthesis and release of polyamines, which allosterically potentiate NMDA receptor open-channel time at the NR2B subunit. The current studies investigated effects of 10 day EtOH and corticosterone (CORT) co-exposure on toxicity during EWD in rat organotypic hippocampal slice cultures, and alterations in function and/or density of the NR2B subunit of the NMDA receptor that may mediate CORT-potentiation of toxicity during EWD. We hypothesized that toxicity during withdrawal following EtOH and CORT co-exposure would be greatest in the CA1 region due to increased NMDA NR2B receptor abundance and/or function. Cultures were exposed to CORT (0.01–1 μM) during 10 day EtOH exposure (50 mM) and 1 day EWD. Additional EtOH-naïve cultures were exposed to CORT for 11 days. Propidium iodide (PI) was used to measure toxicity in the CA1, CA3, and DG hippocampal regions. In EtOH-naïve cultures, 11 day exposure to CORT (0.01 – 1 μM) produced modest toxicity and in all regions. Exposure to CORT during EtOH exposure/EWD potentiated CORT-toxicity at all concentrations in the CA1 region. Ifenprodil, an NR2B polyamine site antagonist, significantly reduced toxicity from EtOH and CORT (0.1 μM) co-exposure during withdrawal. Immunohistochemistry and Western blot analyses were conducted for measurement of NR2B immunoreactivity in organotypic cultures, and autoradiography studies were conducted for measurement of polyamine-sensitive NR2B subunits with [3H]ifenprodil. Consistent increases in NR2B subunit protein were not detected with use of any methodology. Additional studies exposed cultures to a membrane impermeable form of CORT (BSA-conjugated CORT; 0.1 μM) with or without EtOH exposure and withdrawal. BSA-CORT exposure did not produce toxicity in any hippocampal region, suggesting that CORT toxicity was not mediated by membrane bound substrates. These data suggest that CORT and EtOH co-exposure result in increased function of polyamine-sensitive NR2B subunits, but this toxicity does not appear dependent on the number of hippocampal NMDA NR2B subunits.

No description available.

The two-hit hypothesis of schizophrenia proposes that the development of the illness involves an early neurodevelopmental stress component which increases vulnerability to later stressful life events, in combination leading to overt disease. This thesis describes a two-hit animal model, comprising of an early first hit in the form of 24 hours maternal deprivation on postnatal day 9, and a late second hit simulated by 2 weeks of corticosterone administration from 8 to 10 weeks of age in rats. The project included behavioural studies on prepulse inhibition (PPI) regulation, locomotor activity, and learning and memory, and neurochemical and molecular studies on dopaminergic parameters, brain-derived neurotrophic factor (BDNF) and glucocorticoid receptor (GR) expression. / In the two-hit animals, there was little effect on baseline PPI or locomotor activity. However, the effect of acute treatment with the dopaminergic stimulants, apomorphine, amphetamine and quinpirole, was markedly diminished. There were differential effects of either maternal deprivation or corticosterone administration on the action of these drugs. However, there was no change in any of the groups in the effect of the serotonin-1A receptor agonist, 8-OH-DPAT, on PPI, or the effect of amphetamine and phencyclidine on locomotor activity. (For complete abstract open document)

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 114-134).

The Australian Zebra Finch, Taeniopygia guttata, is a common vertebrate model for understanding behavioral, neurological, and physiological changes across the life span. The goal of this study was to determine if color in the environment can act as a stimulus and activate the zebra finch stress response. Zebra finches are diurnal and have color vision. Their plumage coloration is sexually dimorphic and they show behavioral changes to color; females prefer males with redder beaks, and both sexes show individual color preferences for materials in nest building. This experiment was conducted to test whether or not a novel color in the environment can elicit a stress response. A colored poster board was introduced to the adult zebra finches’ habitat, and behavioral changes were measured immediately and then again after twenty four hours. In addition, plasma corticosterone (CORT), the main avian stress hormone, concentrations were measured twenty four hours after introduction of the color stimulus. The introduction of the color stimuli resulted in immediate behavioral changes in the birds and increased activity was observed with the addition of green, blue, and red stimuli and decreased activity with the addition of yellow. However, after twenty four hours there were no changes in behavior or plasma CORT levels for any of the colors. These findings suggest that zebra finches show varied behavioral responses to novel stimuli based on color differences and that these changes are temporary.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / O objetivo deste trabalho foi analisar as alterações estruturais e bioquímicas na parede da bexiga resultante do tratamento crônico de ratos pré-púberes com altas doses de corticosterona. Foram estudados 26 ratos Wistar divididos em quatro grupos: T30 foi tratado com corticosterona até 29 dias de idade e morto no dia 30. T65 recebeu o mesmo tratamento, mas foi morto com 65 dias. Cada grupo tinha seu próprio controle (C30 e C65). Os animais foram tratados com injeções intraperitoneais diárias de corticosterona (2 mg/100g peso corporal) entre o 7 e 29 dias de vida. A bexigas foram removidas e processadas para inclusão em parafina. Foram estudados os seguintes elementos da parede vesical: Colágeno, músculo liso, fibras do sistema elástico, densidade vascular e do epitélio. Estes parâmetros foram analisados por métodos morfométricos, imunofluorescência e bioquímica. A densidade vascular na lâmina foi reduzida em 40% (p <0,05) no grupo T65. A organização do colágeno foi alterada em T30 e T65, apesar da concentração de colágeno total não ser alterada. O grupo T65 teve um aumento de fibras do sistema elástico. Não houve diferença na altura e na densidade de células epiteliais entre os grupos. Quanto à densidade de fibras musculares lisas, observamos um aumento de 19% (p <0,05) no grupo T65. A administração de corticosterona na fase pré-púbere provoca modificações estruturais na bexiga de ratos afetando de modo significativo o substrato morfológico sob qual repousa a fisiologia vesical. Foi observado também que estas modificações normalmente aparecem num tempo mais longo após o término do tratamento / The aim of this work was to analyze the structural and biochemical changes on the bladder wall resulting from the chronic treatment of prepubertal rats with high doses of corticosterone. This study included 26 male Wistar rats assigned to four groups: T30 was treated with corticosterone until 29 days of age and killed at day 30, while T65 group received the same treatment but was killed at day 65. Each group had its own control group (C30 and C65). For treated animals, daily intraperitoneal injections of corticosterone (2 mg/100g body weight) were administered between 7th and 29th day of life. Bladders were removed and collagen, smooth muscle, elastic fibers system, vascular density and epithelium were analyzed by morphometrical methods, immunofluorescence, and biochemistry.Vascular density in lamina propria was reduced by 40% (p<0.05) in group T65. Collagen organization was altered in T30 and T65, although total collagen concentration was unchanged. The T65 group had an increase in elastic system fibers. There was no difference in epithelial height and cell density between the groups. Concerning the smooth muscle fibers density we observed a 19% increase (p<0.05) in the T65 group. Our results show that prepubertal administration of corticosterone induces structural modifications in the bladder of rats

Orientador: Roberto de Oliveira Roça / Resumo: Apesar da elevada tecnificação dos frigoríficos, ainda são constatados prejuízos no rendimento e qualidade do produto final decorrentes de falhas durante o transporte de frangos de corte. Objetivou-se neste estudo avaliar perdas provenientes durante o transporte de frangos entre um frigorífico brasileiro e um inglês, através da mensuração da mortalidade de chegada e contusões parciais correlacionando-as com diferentes distâncias granja-abatedouro, assim como com a sazonalidade. Para avaliar o estresse dos animais, foram mensurados níveis de corticosterona relacionados com as diferentes distâncias. Dados de mortalidades de chegada brasileiros foram mais de 600% superiores quando comparados aos ingleses. Durante o verão, observaram-se maiores índices de mortalidade no estabelecimento brasileiro, enquanto o mesmo foi observado durante o inverno no estabelecimento inglês. No Brasil, a mortalidade de chegada foi influenciada pela distância granja-abatedouro no verão, enquanto no estabelecimento inglês foi mais proeminente nas maiores distâncias durante o inverno. Na Inglaterra, contusões parciais permaneceram constantes, independente das distâncias granjaabatedouro, por outro lado, quando avaliada a sazonalidade, as contusões foram superiores no inverno. Taxas de contusões parciais brasileiras foram mais de 1700% superiores quando comparadas às inglesas, e na distância longa foram observados os maiores índices de contusões. Avaliando-se níveis de corticosterona, dados brasileiros ... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

The objective of this study was to examine the handling influence on breath rate and plasma corticosterone in adult common voles. Furthermore, the examination of relationship between physiological and personality traits was performed. A device consisting of chamber, pressure sensor and oscilloscope measured the breath rate. Enzyme-linked immunosorbent assay (ELISA) was used for corticosterone analysis. Behavioural characteristics were assessed in Open field test (OFT) and Elevated Plus Maze (EPM). The results did not prove the significant impact on resting breath rate and plasma corticosterone level. However, the handled individuals had nearly significantly lower stress breath rate compared to the non-handled individuals. Significant relationship between breath rate and behavioural traits was not detected. Nevertheless, the individuals with lower stress-induced plasma corticosterone performed significantly longer exploration in Elevated Plus Maze.