Browsing by Subject "testosterone"
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Item Analysis of estrone sulphate, testosterone, and cortisol concentrations around time of ejaculation and potential correlation to sexual behavior and sperm characteristics in stallions(2010-07-14) Seale, JenniferIn the stallion, inconsistent sexual behavior and variable semen quality are common. This reproductive variability has been attributed to differences in circulating hormone concentrations. In order to further examine this relationship, 7 miniature stallions were observed for sexual behavior and semen characteristics. Blood was also drawn from each stallion 15 min before mating (time -15), immediately following ejaculation (time 0) and at times following ejaculation (times +15, +30, and +60). Plasma was later analyzed for concentrations of testosterone (T), estrone sulphate (ES) and cortisol. Semen was evaluated for volume, sperm concentration and progressive motility. Sexual behavior was quantified by assigning a libido score to each stallion, recording reaction time and the number of jumps required for ejaculation. Upon statistical analysis, data revealed both ES and cortisol increased at the time of semen collection (P < 0.05), while T did not. Regression analysis revealed that ES and the ratio of ES to T at times -15, +30, and +60 were negatively correlated to libido scores. Additionally, a positive relationship was found between ES at times -15 and +60 and reaction time, as well as between cortisol at times -15, 0, and +15 and libido scores. No relationship was observed between T and sexual behavior. However, T at time -15 was positively correlated to progressive motility, and the ratio of ES/T at time -15 was negatively correlated to progressive motility. No other association was detected between ejaculate parameters and hormone concentrations. These results not only serve to enhance understanding of stallion hormone profiles, but also provide further insight into the hormonal control of sexual behavior and sperm production. This knowledge can be used to generate improved management techniques for stallions that are inconsistent in sexual behavior and sperm output.Item Male body image: testosterone's response to body comparisons(Texas A&M University, 2006-08-16) Brown, Joshua D.Although there have been only a few etiological studies that have examined the development and maintenance of body image in males, research fairly consistently reports that exposure and presumed comparison to images of ideal male bodies increases body dissatisfaction. Social comparison provides individuals with a mechanism by which to evaluate their body appearance to those around them. When individuals compare their bodies to those of others, they are attempting to gauge their standing or status relative to those around them, the results of which have inherent status implications. There is increasing empirical evidence that suggests perceived increases in status result in increased testosterone levels, whereas testosterone decreases when status is perceived as having been diminished. Thus, the core of the present study: can the process of comparing the appearance of one??s body to that of others affect the testosterone levels, body satisfaction, and mood of males? To examine the above research questions, a two-part study was designed. A pilot study was conducted with 117 male undergraduates primarily to examine the psychometrics of measures to be used in the main study. The measures appeared psychometrically sound and were thus used in the main study. In the main study, 129 male undergraduates were exposed to photographs of one of three male body types (i.e., lean/muscular, skinny, average) to determine whether or not exposure to the different body types differentially affected participants?? testosterone levels, body satisfaction, and mood. Results indicate that testosterone levels decreased over the course of the experiment in each of the three groups; however, the body type to which participants were exposed did not differentially affect participants?? testosterone levels. Body dissatisfaction was greater among participants who viewed lean/muscular bodies than those who viewed average bodies. Lastly, mood was not differentially affected by viewing different types of male bodies. Implications and possible explanations for these results are discussed.