Changes in the substance P-containing innervation of the lumbosacral spinal cord in male Wistar rats as a consequence of ageing

Quantitative image analysis was used to determine age-related changes in the substance P-containing innervation of autonomic and somatic nuclei in the lumbosacral spinal cord, which are associated with the control of micturition and sexual reflexes. In the upper lumbar segments (L1-L2), significant declines in the distribution density of substance P-containing processes were observed in the dorsal grey commissure, the intermediolateral cell column and the ventral horn. More caudally, at levels corresponding to L5 through S1, significant reductions were seen in the dorsal grey commissure and within the sacral parasympathetic nucleus. In contrast to these observations, the substance P-immunoreactive innervation of the dorsolateral nucleus remained robust in aged animals and was not significantly different from young adults. It is possible that these distinct age-related patterns of change in substance P-containing innervation, are reflected in the urinary/sexual dysfunction's in aged animals.