Correlation of astrogliosis and substance P immunoreactivity in the brainstem of victims of sudden infant death syndrome.

Substance P is a neuropeptide localized to selected neurons some of which may be involved in respiratory regulation. Substance P appears to be increased in the brainstem under conditions of hypoxia. A quantitative analysis of immunoreactivity to glial fibrillary acidic protein and substance P in the pons of 20 SIDS victims showed astroglial proliferation in the reticular formation and pontine nuclei and an increase of substance P in trigeminal fibers compared with age-matched controls. These observations suggest that in SIDS the neurons in the vicinity of the astrogliosis may be altered as indicated by the apparent increased expression of substance P, although the functional significance of this change on respiratory control is undetermined.