Acute inflammation induces segmental, bilateral, supraspinally mediated opioid release in the rat spinal cord, as measured by mu-opioid receptor internalization.

ABSTRACT: The objective of this study was to measure opioid release in the spinal cord during acute and long-term inflammation using mu-opioid receptor (MOR) internalization. In particular, we determined whether opioid release occurs in the segments receiving the noxious signals or in the entire spinal cord, and whether it involves supraspinal signals. Internalization of neurokinin 1 receptors (NK1Rs) was measured to track the intensity of the noxious stimulus. Rats received peptidase inhibitors intrathecally to protect opioids from degradation. Acute inflammation of the hind paw with formalin induced moderate MOR internalization in the L5 segment bilaterally, whereas NK1R internalization occurred only ipsilaterally. MOR internalization was restricted to the lumbar spinal cord, regardless of whether

SUBMITTER: Chen W 

PROVIDER: S-EPMC2727879 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature