Age-dependent changes in phosphorylated cAMP response element-binding protein immunoreactivity in motoneurons of the spinal nucleus of the bulbocavernosus of male rats.

Phosphorylated cAMP response element-binding protein (CREB) immunoreactivity was examined in motoneurons of the spinal nucleus of the bulbocavernosus (SNB) in young and old male rats by immunohistochemistry. In young animals, intense CREB immunoreactivity was confined to the cell nucleus, but not in the nucleolus of SNB motoneurons. In old animals, both the intensity of CREB immunoreactivity in the nuclei and number of CREB immunoreactive nuclei of the SNB motoneurons were significantly reduced. A marked decline in expression of CREB in the aged SNB motoneurons suggests alternation of cAMP-mediated regulation of gene expression in the SNB system with advancing age.