Changes with aging in the modulation of macrophages by norepinephrine

The effect of aging on the norepinephrine (NE)-induced modulation of phagoc ytic and oxygen-dependent microbicidal processes of mouse peritoneal macrop hages was studied. Phagocytosis of latex beads on culture plates and supero xide anion production was evaluated in young (12 weeks), adult (22 weeks), mature (48 weeks) and old (72 weeks) BALB/c mice after in vitro incubation with 10(-12), 10(-9), 10(-7), 10(-5) or 10(-3) M concentrations of NE. The results indicate that the phagocytic response to NE is quite similar in you ng and mature mice, with increased phagocytosis after incubation with 10(-7 ) and 10(-3) M, and decreased phagocytosis with 10(-5) M. Macrophages from adult mice increased their phagocytic capacity after incubation with the hi ghest concentrations of NE (10(-5) and 10(-3) M) and macrophages from old a nimals only were stimulated with 10(-3) M. In addition, it was found that u sually NE increased the extracellular superoxide anion production in the ab sence of phagocytosis in adult mice. No statistically significant changes w ere found in intracellular superoxide anion levels, but an increase was see n after phagocytosis in macrophages from adult, mature and old animals, esp ecially after incubation with 10(-5) M. In conclusion, the results obtained indicate that the modulation of macrophages by NE does not only depend on the concentration of this neurotransmitter, but also on age. (C) 2000 Elsev ier Science Ireland Ltd. All rights reserved.