The influence of chronic stress on multiple opioid peptide systems in the rat: pronounced effects upon dynorphin in spinal cord |
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Authors: | Ryszard Przew ocki, W adys aw Laso , Volker Ho
llt, Jerzy Silberring,Albert Herz |
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Affiliation: | Ryszard Przewłocki, Władysław Lasoń, Volker Ho¨llt, Jerzy Silberring,Albert Herz, |
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Abstract: | 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. |
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Keywords: | Opioid peptide Spinal cord Chronic foot shock Pain |
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