The relationship of beta-endorphin and ACTH in the cerebrospinal fluid and plasma of adult surgical patients.

Cerebrospinal fluid and plasma beta-endorphin/beta-lipotropin immunoreactivity and adrenocorticotropin hormone were determined in simultaneously obtained samples from 25 healthy, adult surgical patients about to undergo spinal anesthesia using radioimmunoassay techniques. Cerebrospinal fluid adrenocorticotropin concentrations were significantly higher than those in plasma (25.76 +/- 2.11 fm/ml vs. 8.83 +/- 0.84 fm/ml), whereas beta-endorphin/beta-lipotropin concentrations in cerebrospinal fluid were significantly lower than those in plasma (6.60 +/- 0.43 fm/ml vs. 3.35 +/- 0.30 fm/ml). In cerebrospinal fluid, a significant positive correlation was found between beta-endorphin/beta-lipotropin and adrenocorticotropin (r = 0.64, p less than 0.01), whereas no such relationship could be demonstrated in plasma. This suggests that beta-endorphin/beta-lipotropin and adrenocorticotropin might enter the cerebrospinal fluid via a mechanism unrelated to their entry into plasma. This may have implications for the pharmacologic manipulation of these peptides within the central nervous system.