Fig 4. Immunohistochemistry and quantification of 5-HT and its receptor in SCI groups and uninjured rats.
(A) Robust up-regulation of the 5-HT2A receptor at the lumbar motor neurons of the spasticity-strong group compared with the -weak group and uninjured group (scale bars: 50 μm). (B) Quantification of the 5-HT2A receptor-positive (+) area within spinal motor neurons labeled as ChAT positive (+) at both the cervical region and the lumbar region. (C) The 5-HT fibers were almost completely lost after 250-kd contusive SCI, but were more reduced at the spasticity-strong group (scale bars: 50 μm). (D) Quantification of the area of 5-HT fibers at both the cervical and the lumbar ventral horn region. Values were normalized considering the value for uninjured rats as 100%. (E) Plots of the quantification of 5-HT2A receptor expression and 5-HT fibers at the cervical and lumbar region, respectively in uninjured (yellow), spasticity-strong group (purple), and -weak group (pink). **: p < 0.01, ***: p < 0.001 Abbreviations: 5-HT, 5-Hydroxytryptophan; ChAT, Choline acetyltransferase; n.s, not significant.