Immunoreactive β-Endorphin in Human Cerebrospinal Fluid*

To elucidate the nature of beta-endorphin-like immunoreactivity in human cerebrospinal fluid (CSF) and its relationship with plasma beta-endorphin, plasma and CSF specimens were obtained simultaneously. Gel chromatography revealed that beta-endorphin-like immunoreactivity in CSF consisted of two components with elution positions compatible to those of beta-endorphin and beta-lipotropin (beta-LPH), respectively, and an additional larger molecule. The beta-endorphin level in CSF obtained from four nonendocrine patients was 17.9 +/- 2.3 pg/ml (mean +/- SE) and corresponded to 20% of beta-endorphin-like immunoreactivity. The predominant componet in CSF was either beta-LPH or the larger molecule. beta-Endorphin levels in CSF were consistently higher than those in plasma, and there seemed to be no relationship between them. One patient with Nelson's syndrome had a CSF beta-endorphin level of 14.8 pg/ml, although the plasma level was 784 pg/ml. On the other hand, one patient under glucocorticoid treatment had a CSF beta-endorphin level of 13.0 pg/ml and an undetectably low plasma level. It is concluded that 1) beta-endorphin-like immunoreactivity consists of beta-endorphin, beta-LPH, and possibly the precursor molecule; and 2) there exists marked dissociation between plasma and CSF beta-endorphin levels, suggesting the possible central nervous system origin of beta-endorphin in CSF.