EFFECTS OF NATURAL AGING ON PLASMA 5-HT TURNOVER IN HUMANS

There is consistent preclinical evidence that brain 5-HT and 5-HIAA co ncentrations are abnormal during natural ageing (Kabuto et al., 1995). Furthermore, plasma/CSF 5-HT and 5-HIAA concentrations are reduced in both vascular and Alzheimer's type dementia, which may be due to abno rmal progressive cell degeneration (Parnetti et al., 1994). However, e ffects of natural ageing on plasma 5-HT, 5-HIAA and 5-HT turnover rema in unclear. Therefore, we investigated the relationship between 5-HT t urnover and age in 44 subjects (M:F = 22:22; age range: 21-63 years). We determined plasma 5-HT and 5-HIAA, after an overnight fasting and b lind to subject status, by an HPLC-fluorescent detection method (Bearc roft et al., 1995), and 5-HT turnover was calculated as [5-HIAA]divide d by[5-HT]. These results indicate that 5-HT turnover is positively co rrelated with natural ageing, suggesting that ageing may alter 5-HT sy stem in humans. However, further large scale studies are required to c onfirm these results and to investigate their significance. (C) 1997 J ohn Wiley & Sons, Ltd.