RT Journal Article
SR Electronic
T1 A model of chronic pain in the rat: response of multiple opioid systems to adjuvant-induced arthritis
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 899
OP 906
DO 10.1523/JNEUROSCI.06-04-00899.1986
VO 6
IS 4
A1 MJ Millan
A1 MH Millan
A1 A Czlonkowski
A1 V Hollt
A1 CW Pilcher
A1 A Herz
A1 FC Colpaert
YR 1986
UL http://www.jneurosci.org/content/6/4/899.abstract
AB Chronic arthritic pain was induced by intradermally inoculating rats at the tail-base with Mycobacterium butyricum, which results in swelling, inflammation, and hyperalgesia of the joints. These symptoms peak at 3 weeks after inoculation and disappear by 10 weeks. The following changes were seen at 3 weeks. Immunoreactive dynorphin (ir-Dyn) and ir- alpha-neo-endorphin (alpha-NE) manifested comparable patterns of change. Their levels were increased in the anterior, but not neurointermediate, pituitary. The thalamus showed a rise in ir-Dyn and ir-alpha-NE, but no alterations were seen in other brain regions. In each case, cervical, thoracic, and lumbosacral sections of the spinal cord showed a rise in ir-Dyn and ir-alpha-NE: This was most pronounced in the lumbosacral region, where the magnitude of these shifts correlated with the intensity of arthritic symptoms. In addition, a moderate elevation in ir-methionine-enkephalin (ME) was seen in lumbosacral spinal cord. In brain, ir was not changed. The level of ir- beta-endorphin (beta-EP) was elevated both in the plasma and the anterior, but not the neurointermediate, pituitary. In addition, the content of messenger RNA encoding the beta-EP precursor, proopiomelanocortin (POMC), was enhanced in the anterior lobe. Thus, there was a selective activation of synthesis of beta-EP in, and its secretion from, the anterior lobe. In no brain tissue did levels of ir- beta-EP change. At 10 weeks postinoculation, the above changes were no longer apparent, indicating their reversibility.(ABSTRACT TRUNCATED AT 250 WORDS)