Brain research. Molecular brain research
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Brain Res. Mol. Brain Res. · May 1989
Preproenkephalin gene expression in the rat spinal cord after noxious stimuli.
The trans-synaptically activated biosynthesis of the preproenkephalin (PPE) mRNA in the dorsal horn of the rat lumbar spinal cord was examined by an in situ hybridization histochemical technique. As a nociceptive stimulus, a small amount of formalin was injected into the right hindpaw, and quantitative and qualitative changes of PPE-mRNA expression were determined by emulsion autoradiography. ⋯ Expression of PPE-mRNA increased within 1 h after formalin injection in neurons of deep layers, but gradually for at least 24 h in neurons in the superficial layers. These results at the level of the spinal cord showed that differential responses of PPE neurons related to the pain sensation occurred trans-synaptically after nociceptive stimulation applied to the periphery.