Abstract
There is circumstantial evidence in relationship between exercise strength and endorphin contents. However, little is known about the relationship between exercise frequency and changes in beta-endorphin levels. Therefore, the present study was carried out to examine the relationship between exercise frequency and beta-endorphin levels using rat experimental model.F344 male rats, 6 weeks of age, were exercised in treadmill at 10 and 20 m/min twice or three times per day. One hour after the exercise, hypothalamus was taken from the whole brain and the beta-endorphin level in water extracts of the hypothalamus was measured by ELISA.Exercise at 10 m/min did not affect the beta-endorphin levels: the beta-endorphin levels in those rats were nearly identical to that observed in controls. On the other hand, exercise at 20 m/min for three times per day, but not twice per day, affected the endocrine system and caused significant increase in beta-endorphin levels as compared with those in control. These results suggest that low strength levels of exercise, such as 10 m/min did not affect endocrine system, but much higher strength levels of exercise caused changes in endocrine system. [J Physiol Sci. 2007;57 Suppl:S173]
