Immunoreactive β-endorphin and adrenocorticotropin in human cerebrospinal fluid

Abstract

To elucidate the significance of β-endorphin in human cerebrospinal fluid (CSF), CSF levels of β-endorphin-like immunoreactivity (β-EP-LI) in various diseases were determined by a specific radioimmunoassay and compared with simultaneously determined ACTH-like immunoreactivity (ACTH-LI) levels in CSF. CSF β-EP-LI and ACTH-LI in the control group, consisting of 5 normal subjects and 19 patients with nonendocrine diseases, were 22.2±1.3 and 14.6±0.4 fmol/ml, respectively. CSF levels of these peptides in patients with schizophrenia (n = 19) and acromegaly (n = 10) were not significantly different from those in the control group. Patients with Cushing's disease (n = 7) had significantly lower CSF β-EP-LI and ACTH-LI levels than those in the control group. Four of them showed a parallel increase in CSF β-EP-LI and CSF ACTH-LI levels after the complete removal or pituitary microadenomas (P <0.05). Gel chromatography of CSF β-EP-LI from a normal volunteer, a control patient, and one patient each with catatonia, Nelson's syndrome, Cushing's syndrome (adrenal adenoma), and acromegaly gave a similar patterns consisting of three peaks with the elution positions comparable to those of authentic β-endorphin, β-lipotropin, and possibly their precursor molecule. Gel chromatographic patterns of CSF β-EP-LI and ACTH-LI were compared in a normal volunteer. The first peaks of β-EP-LI and ACTH-LI eluted at the same position and the second peak of ACTH-LI coincided with the elution position of authentic ACTH. CSF β-EP-LI and ACTH-LI levels determined every 5 min over a period of 80 min in three normal volunteers did not show moment-to-moment variability. A significant correlation (r = 0.75, P <0.001) was seen between CSF β-EP-LI and ACTH-LI levels in normal subjects and patients studied (n = 73). This suggests that β-endorphin and ACTH in human CSF share the common regulatory mechanism in normal and pathologic conditions.