Plasma levels of beta-endorphin in young and aged human males during the morning hours

Age-related alterations in plasma levels of beta-endorphin (BE) were investigated in young and aged human males. This was accompanied by obtaining repeated measurements of BE levels in the plasma of young and aged human male subjects during the morning hours, when a diurnal elevaiton of BE in the plasma is reported to occur. BE was extracted from the plasma and measured by radioimmunoassay. No differences were found in plasma levels of BE between young and elderly males at any time during the time period studied. In addition, the mean level of BE in the plasma during the entire sampling period did not differ between the two age groups. These data suggest that in human males, the levels of BE in the plasma during the morning hours are not modified by aging.