Stress-Related Changes in beta-Endorphin Processing: The Limitations of Slaughterhouse Material.
Abstract In the sheep, unlike many other species, a significant proportion (>25%) of immunoreactive beta-endorphin in the anterior pituitary is post-translationally modified to opioid-inactive, alpha-N-acetylated forms. In a study to determine the precise molecular nature of alpha-N-acetylated beta-endorphin immunoreactivity, we noted a striking difference in high-performance liquid chromatography profiles of anterior pituitary extracts between sheep killed on the farm, and age-, sex- and strain-matched slaughterhouse animals. These altered patterns of a-N-acetylated beta-endorphin processing were reproduced in farm animals by chronic (</= 4 days) treatment with the synthetic glucocorticoid dexamethasone; in contrast dexamethasone had no effect on a-N-acetylated beta-endorphin processing in hypothalamo-pituitary disconnected sheep. These data suggest that (1) the change in processing is a stress response, mediated by prolonged glucocorticoid exposure, (2) this effect is central, rather than a direct effect on the pituitary, and (3) the relative abundance of various peptide sequences in slaughterhouse-derived material may not reflect their abundance under more physiological conditions.
Smith
A I
AI
Medical Research Centre, Prince Henry's Hospital, Melbourne, Australia 3004.
Wallace
C A
CA
Clarke
L J
LJ
Funder
J W
JW