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No description available.

Call number: LD2668 .T4 1986 N484 / Master of Science / Animal Sciences and Industry

O objetivo deste trabalho foi desenvolver um protocolo de extração hormonal à partir de fezes de onça-pintada (Panthera onca) e validar uma metodologia de análise destes extratos por eletroforese capilar, verificando a eficiência analítica desta técnica no estudo dos metabólitos de esteróides sexuais em fezes, com o intuito de utilização futura desta metodologia na rotina dos laboratórios de endocrinologia. Foram testados sete tratamentos para as amostras de fezes liofilizadas: quatro protocolos de extração em diferentes solventes, um de hidrólise ácida e dois protocolos de extração em fase sólida (SPE). O protocolo de extração em acetonitrila foi satisfatório como pré-tratamento da amostra e aliado à SPE C-18 apresentou bons resultados no que diz respeito à sensibilidade, precisão, recuperação e tempo de análise. Com base nos resultados obtidos, a eletroforese capilar pode ser considerada uma ótima alternativa para a prospecção de metabólitos de hormônios, podendo ser utilizada em análises de rotina nos laboratórios de endocrinologia animal, sobretudo naqueles que se dedicam às metodologias não-invasivas de avaliação da função reprodutiva em animais selvagens. / The objective of this work was to develop a protocol of hormonal extraction from jaguar feces (Panthera onca) and validate a methodology of analysis of these extracts with capillary electrophoresis, verifying the analytical efficiency of this technique in the study of the steroids metabolites in feces, with the objective of future use of this methodology in the routine of the endocrinology laboratories. Seven treatments were tested for the samples: four extraction protocols in different solvents, one of acid hydrolysis and two extraction protocols in solid phase (SPE). The extraction protocol in acetonitrila was satisfactory as pre-treatment of the samples and ally to SPE C-18, it presented good results with respect to the sensibility, precision, recovery and time of analysis. Based on the obtained results, the capillary electrophoresis can be considered a great alternative for the research of metabolites of hormones, it could also be used in routine analyses in the endocrinology laboratories, mainly in those that are devoted to the non-invasive evaluation methodologies of the reproductive function in wild animals.

Cabras leiteiras das raças Saanen e Toggenburg (n=10) mantidas num rebanho particular no Estado de São Paulo tiveram seus níveis séricos de progesterona e estradiol comparados às concentrações fecais, durante o período correspondente a três ciclos estrais. O perfil hormonal foi confrontado com as manifestações comportamentais de estro visando uma contribuição ao conhecimento do ciclo das cabras destas raças em condições brasileiras, que leve a um manejo reprodutivo mais eficiente. As correlações entre níveis séricos e fecais foram calculadas, sugerindo a validade do modelo de dosagem hormonal nas fezes em cervídeos. Foi verificada correlação extremamente significante entre as concentrações séricas de progesterona e as de progestinas fecais, com r=0,83 e p<0,0001. Entre as concentrações séricas de estradiol e as de seus metabólitos nas fezes não foi verificada correlação significante, com r=-0,16 e p<0,3916. A partir da observação dos resultados e sua análise estatística, pode-se concluir que, dentro das condições deste trabalho, as concentrações de progestinas fecais apresentam variação correspondente à da progesterona sérica ao longo do ciclo estral das cabras; por outro lado, diferentemente das observações de outros autores, o mesmo não ocorre com os metabólitos fecais do estradiol em relação ao estradiol sérico. / Saanen e Toggenburg dairy goats (n=10) kept in a private flock in São Paulo State had their serum levels of progesterone and estradiol compared to faecal concentrations of the respective metabolites, through an interval corresponding to 3 estrous cycles. Hormonal profile was checked with behavioural manifestations of estrous searching for a better knowledge of the cycle of these breeds in brazilian environment, leading to a more efficient reproductive management. Correlations between serum and faecal levels were calculated, suggesting that the model of faecal hormone measurements could be valuable in cervidae. It was found an extremely significant correlation between progesterone serum concentration and progestin faecal concentration, with r=0,83 and p<0,0001. Between estradiol serum concentrations and its faecal metabolites? concentrations no significant correlation was found, with r=-0,16 and p<0,3916. Based on results observation and statistical analysis, we can assume that, in the circumstances of this trial, progestin faecal concentrations show a variation profile similar to that one of serum progesterone, through estrous cycle of goats; however, this fact could not be observed for estradiol metabolites, compared to serum estradiol concentrations.

Cabras leiteiras das raças Saanen e Toggenburg (n=10) mantidas num rebanho particular no Estado de São Paulo tiveram seus níveis séricos de progesterona e estradiol comparados às concentrações fecais, durante o período correspondente a três ciclos estrais. O perfil hormonal foi confrontado com as manifestações comportamentais de estro visando uma contribuição ao conhecimento do ciclo das cabras destas raças em condições brasileiras, que leve a um manejo reprodutivo mais eficiente. As correlações entre níveis séricos e fecais foram calculadas, sugerindo a validade do modelo de dosagem hormonal nas fezes em cervídeos. Foi verificada correlação extremamente significante entre as concentrações séricas de progesterona e as de progestinas fecais, com r=0,83 e p<0,0001. Entre as concentrações séricas de estradiol e as de seus metabólitos nas fezes não foi verificada correlação significante, com r=-0,16 e p<0,3916. A partir da observação dos resultados e sua análise estatística, pode-se concluir que, dentro das condições deste trabalho, as concentrações de progestinas fecais apresentam variação correspondente à da progesterona sérica ao longo do ciclo estral das cabras; por outro lado, diferentemente das observações de outros autores, o mesmo não ocorre com os metabólitos fecais do estradiol em relação ao estradiol sérico. / Saanen e Toggenburg dairy goats (n=10) kept in a private flock in São Paulo State had their serum levels of progesterone and estradiol compared to faecal concentrations of the respective metabolites, through an interval corresponding to 3 estrous cycles. Hormonal profile was checked with behavioural manifestations of estrous searching for a better knowledge of the cycle of these breeds in brazilian environment, leading to a more efficient reproductive management. Correlations between serum and faecal levels were calculated, suggesting that the model of faecal hormone measurements could be valuable in cervidae. It was found an extremely significant correlation between progesterone serum concentration and progestin faecal concentration, with r=0,83 and p<0,0001. Between estradiol serum concentrations and its faecal metabolites? concentrations no significant correlation was found, with r=-0,16 and p<0,3916. Based on results observation and statistical analysis, we can assume that, in the circumstances of this trial, progestin faecal concentrations show a variation profile similar to that one of serum progesterone, through estrous cycle of goats; however, this fact could not be observed for estradiol metabolites, compared to serum estradiol concentrations.

O objetivo deste trabalho foi desenvolver um protocolo de extração hormonal à partir de fezes de onça-pintada (Panthera onca) e validar uma metodologia de análise destes extratos por eletroforese capilar, verificando a eficiência analítica desta técnica no estudo dos metabólitos de esteróides sexuais em fezes, com o intuito de utilização futura desta metodologia na rotina dos laboratórios de endocrinologia. Foram testados sete tratamentos para as amostras de fezes liofilizadas: quatro protocolos de extração em diferentes solventes, um de hidrólise ácida e dois protocolos de extração em fase sólida (SPE). O protocolo de extração em acetonitrila foi satisfatório como pré-tratamento da amostra e aliado à SPE C-18 apresentou bons resultados no que diz respeito à sensibilidade, precisão, recuperação e tempo de análise. Com base nos resultados obtidos, a eletroforese capilar pode ser considerada uma ótima alternativa para a prospecção de metabólitos de hormônios, podendo ser utilizada em análises de rotina nos laboratórios de endocrinologia animal, sobretudo naqueles que se dedicam às metodologias não-invasivas de avaliação da função reprodutiva em animais selvagens. / The objective of this work was to develop a protocol of hormonal extraction from jaguar feces (Panthera onca) and validate a methodology of analysis of these extracts with capillary electrophoresis, verifying the analytical efficiency of this technique in the study of the steroids metabolites in feces, with the objective of future use of this methodology in the routine of the endocrinology laboratories. Seven treatments were tested for the samples: four extraction protocols in different solvents, one of acid hydrolysis and two extraction protocols in solid phase (SPE). The extraction protocol in acetonitrila was satisfactory as pre-treatment of the samples and ally to SPE C-18, it presented good results with respect to the sensibility, precision, recovery and time of analysis. Based on the obtained results, the capillary electrophoresis can be considered a great alternative for the research of metabolites of hormones, it could also be used in routine analyses in the endocrinology laboratories, mainly in those that are devoted to the non-invasive evaluation methodologies of the reproductive function in wild animals.

Graduation date: 1993

Thesis (M.S.)--Mississippi State University. Department of Animal and Dairy Sciences. / Title from title screen. Includes bibliographical references.

[Truncated abstract] The activity of the reproductive endocrine axis is the result of interactions among many organs and tissues, particularly the hypothalamus, pituitary gland and gonad. However, it depends on more than the communication between anatomical structures because it is also affected by genotype, internal factors (e.g., metabolic inputs) and external factors (e.g., photoperiod, socio-sexual cues, stress, nutrition). This multifactorial complexity makes it difficult to use animal experimentation to investigate the pathways and mechanisms involved. Therefore, in this study, I have turned to mathematical modelling. The general hypothesis was that, by modelling the hormonal feedback loop that links the hypothalamus, pituitary gland and gonad, I would be able to discover the critical control points in this homeostatic system. This would allow me to inform and direct research into the processes that control reproduction, including inputs from environmental factors. My studies began with the development of a model of the negative feedback loop through which testosterone controls the secretion of pulses of gonadotrophin-releasing hormone (GnRH) by the hypothalamus. The model incorporated two critical factors: testosterone concentration and a time delay in the inhibition of the activity of the GnRH 'pulse generator' by testosterone. The general assumptions were: i) there are two positive feedforward processes (GnRH pulses stimulate LH pulses, and, in turn, LH pulses stimulate testosterone secretion); ii) testosterone exerts negative feedback that reduces the frequency of GnRH pulses. The model incorporated a group of equations that represent the GnRH pulse generator, through which the inhibitory effect of testosterone acted to reduce GnRH pulse frequency. Simulations were run with various values for the time delay in feedback and, as model development progressed, the simulations were extended to include combinations of time delays and levels of sensitivity of the GnRH pulse generator to inhibition by testosterone. The output of the simulations showed clearly that a time delay in negative feedback, as well as the concentration of testosterone, can greatly affect the frequency of GnRH pulses and the shape of the GnRH secretory profile. Importantly, the effect of the time delay depends on the sensitivity of the pulse generator to testosterone. In addition, the simulations suggested two additional components that might be involved in the control of the GnRH pulse generator: i) a delay in the rate of adaptation to a change in steroid feedback; and ii) a minimum pulse interval (maximum frequency). These studies iii therefore suggest that the regulation of the activity of the GnRH pulse generator, and thus the frequency and profile of GnRH and LH pulses, requires interactions among these four components. These interactions should be tested in animal experimentation. In the next stage, I extended the model so I could test whether the feedback delay might involve the process of aromatization in which testosterone is converted to oestradiol at brain level. ... This information can be used to direct future experimental studies that will help us to understand the factors that underlie the dynamic behaviour of the hypothalamic and pituitary systems that control reproduction.