Endorphin-related peptides in rat cerebrospinal fluid

Cerebrospinal fluid (CSF) samples were taken from rats implanted with chronic cisternal cannulae and assayed for methionine-enkephalin, β-endorphin and corticotropin (ACTH). Immonubilization stress had little apparent effect on immunoreactive levels of the peptides in the CSF. Gel chromatographic analysis of the β-endorphin- and ACTH-immunoreactive profiles in rat CSF revealed several peaks. β-Endorphin-immunoreactive peaks were present at the expected positions of pro-opiocortin, β-lipotropin and β-endorphin. ACTH-immunoreactive peaks eluted at positions coresponding to pro-opiocortin, the 20–23K ACTH biosynthetic intermediate, 14K ACTH, and 4.5K ACTH. These results suggest that rat CSF contains peptides of the pro-opiocortin family similar to those previously described in rat pituitary.