Substance P immunoreactivity in Rett syndrome

Severe autonomic dysfunction occurs in Rett syndrome (RS), Substance P, a t achykinin peptide that localizes to several brain regions, including the au tonomic nervous system, is reduced in the cerebrospinal fluid of patients w ith RS, The anatomic localization and intensity of substance P immunoreacti vity and glial fibrillary acidic protein-positive astrocytes in the brains of 14 patients with RS were compared with those in the brains of 10 age-mat ched normal patients. Substance P immunoreactivity expression was significa ntly decreased in RS tissue compared with control tissue in the following r egions: dorsal horns, intermediolateral column of the spinal cord, spinal t rigeminal tract, solitary tract and nucleus, parvocellular and pontine reti cular nuclei, and locus ceruleus, A less significant decrease of substance P immunoreactivity occurred in the substantia nigra, central gray of the mi dbrain, frontal cortex, caudate, putamen, globus pallidus, and thalamus, An tiglial fibrillary acidic protein-positive astrocytes were increased in the areas in which substance P immunoreactivity was decreased and in other bra in regions. Because many of the brain regions with the greatest decrease in substance P immunoreactivity are involved in the control of the autonomic nervous system, especially the solitary tracts and reticular formation, red uced substance P may contribute to the autonomic dysfunction in RS. (C) 200 0 by Elsevier Science Inc. All rights reserved.