Effects of neonatal removal of superior cervical ganglion on serotonin and thyrotropin-releasing hormone immunoreactivity in the intermediolateral cell column of the rat spinal cord.

In this study, we investigated the effects of the neonatal removal of the right superior cervical ganglion on the serotonin-like and thyrotropin-releasing-hormone-like immunoreactivities (5-HT-LI and TRH-LI) in the intermediolateral cell column (IML) of the spinal cord by quantitative image analysis. Two weeks after the lesion, we observed a 60% reduction in 5-HT-LI, while TRH-LI was not significantly reduced, in the right IML (lesioned side) at T1-2 levels. One month after the lesion, 5-HT-LI and TRH-LI were significantly reduced by 60% in the right IML at T1-2 levels. After 3 months, this decrease persisted at this level. In addition, we observed a 30% loss of the 5-HT-LI in the right IML at T3-4 levels, whereas TRH-LI did not decrease significantly at T3-4 levels. These findings are discussed and compared with those of other experimental studies on serotonergic reorganization in the rat spinal cord.