| Summary: | 碩士 === 中興大學 === 獸醫學系暨研究所 === 99 === Fatigue confronts many nowadays. It can be caused by excessive exercise, sickness or sleep disturbance and compromised central nervous functions, including reduced activities and impaired concentration, attention and memory. Fatigue is also associated with hypogonadism and aging, suggesting that serum sex hormone may protect against fatigue. In this regard, we found recently that testosterone modulates the dendrites of cortical neurons. In addition, testosterone has been shown to modulate the dendritic morphologies of hippocampal neurons to underlie its effect on cognitive function, including spatial and working memory. In the present study, we used the sleep disturbance-induced fatigue rat model to find out whether testosterone could influence the induction of fatigue. Both intact and castrated rats were subjected to sleep disturbance induction and level of serum testosterone and the extent of fatigue were evaluated. Intracellular dye injection was used to reveal the dendritic structures of corticospinal and hippocampal CA1/CA3 pyramidal neurons. Results revealed that castrated rats performed poorer behaviorally and showed fewer dendritic spines than intact rats. The exogenous testosterone on castrated rat could significantly improve the performances of activity, Morris water maze and weight-loaded forced swimming test. Thus, we suggest that testosterone plays a preventive role against fatigue induction by reducing the dendritic changes of central neurons.
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