Increase of beta-endorphin in cerebrospinal fluid after removal of ACTH-secreting pituitary adenoma.

beta-Endorphin and methionine(met)-enkephalin in cerebrospinal fluid (CSF) were measured before and after removal of an adrenocorticotropic hormone-(ACTH)-secreting adenoma in Cushing's disease by a sensitive radioimmunoassay and a radio-receptor assay, respectively. After tumor resection, the level of ACTH in plasma markedly decreased from 82.6 +/- 22.7 pg/ml to 16.7 +/- 4.1 pg/ml (mean +/- S.E., n = 4). It was found that the level of beta-endorphin in CSF significantly increases from 32.0 +/- 4.5 pg/ml to 61.8 +/- 10.7 pg/ml (P less than 0.05) after tumor resection, while the level of metenkephalin in CSF remained unaltered. This result suggests that hypophysectomy induces an increase of beta-endorphin in CSF.