The influence of chronic stress on multiple opioid peptide systems in the rat: pronounced effects upon dynorphin in spinal cord.
Recurrent exposure to intermittent electrical foot-shock (30 min, twice daily) for 7 days caused an increase in immunoreactive (ir) dynorphin and ir-alpha-neo-endorphin in lumbar and cervical (but not thoracic) spinal cord as measured 16 h following the final session. At this time the level of ir-Met-enkephalin-Arg6-Gly7-Leu8 (MEAGL) was also increased at the lumbar level. An acute foot-shock depleted spinal cord dynorphin in chronically stressed but not in naive rats. No alterations in levels of ir-dynorphin or ir-MEAGL were seen in discrete brain tissues. In contrast to the brain, where no effects were seen, the levels of beta-endorphin increased in both lobes of the pituitary. This change, however, was not accompanied by an alteration in levels of beta-endorphin in plasma. These data show that chronic foot-shock stress selectively influences particular pools of opioid peptides, predominantly those derived from proenkephalin B in the spinal cord and from proopiomelanocortin in the anterior pituitary. It is suggested that alterations observed in the spinal cord reflect enhanced activity of the proenkephalin B system in response to chronic nociceptive stimulation.
D000818:Animals; D001921:Brain / Q000378:metabolism; D004399:Dynorphins / Q000378:metabolism*; D004597:Electroshock; D004723:Endorphins / Q000097:blood / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism*; D013312:Stress, Physiological / Q000378:metabolism* / Q000503:physiopathology; D001615:beta-Endorphin
D004723:Endorphins; D011498:Protein Precursors; D004744:Enkephalin, Methionine; D001615:beta-Endorphin; C025681:alpha-neoendorphin; D004399:Dynorphins; C033453:enkephalin-Met, Arg(6)-Gly(7)-Leu(8)-