Exercise at different intensities is able to induce different physical and psychological statuses of the subjects. The β-endorphin (β-EP) in central nervous system is thought to play an important role in physical exercise. However, its expression patterns and physiological effects in the central nuclei under different exercise states are not well understood. Five-week old male Sprague-Dawley rats were randomly divided into two groups of 21 each: Control and Exercise. Control rats were sedentary while Exercise rats were arranged to run on a treadmill (5-week adapting or moderate exercise and 2-week high-intensity exercise). Seven rats were taken from each group at day33, day42 and day49 for examination of blood biochemical parameters (lactate, Lac; blood urea nitrogen, BUN; glucose) and for detection of nuclei β-EP level with immunohistochemistry. The results showed that Lac and BUN levels were significant increased after the high intensity exercise. The five-week exercise caused a significantly increased β-EP in caudate putamen (CPu), amygdala, paraventricular thalamic nucleus (PVT), ventromedial hypothalamus nucleus (VMH) and gigantocellular reticular nucleus (Gi). The high intensity exercise induced an elevated β-EP in CPu and nucleus of the solitary tract (Sol), but a decreased β-EP in globus pallidus (GP). Compared with Control, exercise rats showed an elevated β-EP in CPu, PVT, VMH, accumbens nucleus, Gi and Sol, and a decreased β-EP in GP at day49. The β-EP levels in acurate nucleus, periadueductal gray and parabrachial nucleus were not changed at day33, 42 and 49. In conclusion, β-EP levels in different nuclei changed under the moderate and high intensity exercises, which may contribute to modifying exercise-produced psychological and physiological effects.

中文翻译：

---

运动诱导大鼠中枢神经系统β-内啡肽表达规律

不同强度的运动能够引起受试者不同的身心状态。中枢神经系统中的β-内啡肽（β-EP）被认为在体育锻炼中起重要作用。然而，其在不同运动状态下的中枢细胞核中的表达模式和生理效应尚不清楚。五周大的雄性 Sprague-Dawley 大鼠随机分为两组，每组 21 只：对照组和运动组。对照大鼠久坐，而运动大鼠则安排在跑步机上跑步（5 周适应或适度运动和 2 周高强度运动）。在第33天、第42天和第49天，每组取7只大鼠用于检查血液生化参数（乳酸、Lac；血尿素氮、BUN；葡萄糖）和用免疫组织化学检测细胞核β-EP水平。结果表明，高强度运动后Lac和BUN水平显着升高。为期五周的运动导致尾壳核 (CPu)、杏仁核、室旁丘脑核 (PVT)、下丘脑腹内侧核 (VMH) 和巨细胞网状核 (Gi) 的 β-EP 显着增加。高强度运动导致 CPu 和孤束核 (Sol) 中的 β-EP 升高，但苍白球 (GP) 中的 β-EP 降低。与对照组相比，第 49 天，运动大鼠的 CPu、PVT、VMH、伏隔核、Gi 和 Sol 中的 β-EP 升高，GP 中的 β-EP 降低。在第33、42和49天，针核、输卵管周围灰质和臂旁核的β-EP水平没有变化。 综上所述，中高强度运动下不同细胞核的β-EP水平发生了变化，