Chapter 20 Regulation of spinal neuropeptide genes in a rat model of peripheral inflammation and hyperalgesia

Publisher Summary This chapter discusses the regulation of spinal neuropeptide genes in a rat model of peripheral inflammation and hyperalgesia. Varieties of neuropeptides have been identified at the spinal level, acting as neurotransmitters or neuromodulators, and play important roles in the processing of nociceptive information. Recent studies indicate that, in the spinal cord, several neuropeptide genes and their resultant peptide products, including dynorphin, enkephalin and substance P, are up-regulated in response to peripheral tissue inflammation. Analysis of the neural circuits accessed by these peptides suggests that their regulation represents, in part, the mechanisms underlying neuronal hyperexcitability and behavioral hyperalgesia at the spinal level. This chapter discusses the changes of three neuropeptides: dynorphin, enkephalin and substance P, especially with regard to their precursor mRNAs in the spinal cord. Analysis of mRNA regulation targets the response of intrinsic spinal cord neurons as mRNA transcription occurs in neuronal cell bodies, while analysis of peptide products can be confounded by the diverse origin of spinal axonal processes from primary afferents or descending axons from higher centers of the neuraxis. The molecular mechanisms of nociception are addressed here, and the neuronal regulation is correlated to development of dorsal horn hyperexcitability and behavioral hyperalgesia.