The effects of aging on spinal neurochemistry in the rat.

The purpose of this study was to investigate how the aging process alters the basal levels of serotonin, norepinephrine, dopamine, and their respective metabolites in the spinal cord using high-performance liquid chromatography and electrochemical detection. Young, mature and aged male Fischer 344 rats (5-6, 15-16, and 25-26 months old, respectively) were used in all experiments. Dorsal and ventral halves of the cervical, thoracic, lumbar and sacral vertebral sections of the rat spinal cord were analyzed. The results indicate that as chronological age increases, local spinal levels of serotonin and norepinephrine decrease. These findings are discussed in terms of how age-related changes in the endogenous levels of the biogenic amines may alter the perception of pain in the elderly.