Expression of 5-HT2A receptor mRNA in rat spinal dorsal horn and some nuclei of brainstem after peripheral inflammation

The expression of 5-hydroxytryptamine (5-HT) (2A) receptor mRNA was studied in the lumbar spinal dorsal hem. nucleus of raphe magnus (NRM), ventrolate ral periaqueductal gray (vIPAG) and dorsal raphe nucleus (DRN) following ca rrageenan inflammation using in situ hybridization technique. The findings of this study demonstrated that 5-HT2A receptor mRNA was expressed with low to moderate levels in lumbar spinal dorsal horn, NRM, vlPAG and DRN. Follo wing carrageenan inflammation, the expression of 5-HT2A receptor mRNA in ip silateral dorsal horn, bilateral NRM, vlPAG and DRN was significantly incre ased. The peak occurred at 3 h and then there was a clear decrease but stil l a substantial number of labeled cells at 24 h after injection of carragee nan. This result suggested that the synthesis of 5-HT2A receptor in enhance d in spinal dorsal horn, NRM, vlPAG and DRN during inflammatory pain. (C) 2 001 Published by Elsevier Science B.V.