抄録
There is circumstantial evidence that long-term, but not short-term, exercise affects the function of endocrine systems and increases beta-endorphin levels in both hypothalamus and plasma in rat experimental model. There is, however, little information about the relationship between exercise strength and changes in beta-endorphin levels. Therefore, the present study was carried out to examine the relationship between exercise strength and beta-endorphin levels using rat experimental model.F344 male rats, 6 weeks of age, exercised in treadmill at 5 to 35 m/min. After one hour, hypothalamus was obtained and beta-endorphin levels in water extracts of hypothalamus were measured by ELISA.Exercise at 5 to 25 m/min did not cause changes in beta-endorphin levels: beta-endorphin levels in experimental rats were nearly identical to those observed in controls. On the other hand, exercise at more than 30 m/min affected the endocrine system and significantly increased in beta-endorphin levels as compared with those in control.Since beta-endorphin is recognized to produce or secrete in hypothalamus in response to several types of stress, these results suggest that exercise at higher speed acts upon rat endocrine systems as a stressor. [Jpn J Physiol 55 Suppl:S209 (2005)]
