Neuropeptide Y effects on murine natural killer activity: changes with ageing and cAMP involvement

Changes in the bidirectional interaction between the nervous and the immune systems have been proposed as a cause of ageing. Neuropeptides, such as ne uropeptide Y (NPY). could show different effects on immune function with ag e. In the present work. we have studied the in vitro action of a wide range of NPY concentrations, i.e. from 10(-13) to 10(-7) M. on natural killer (N K) activity, a function which decreases with age. Spleen, axillary nodes, t hymus and peritoneum leukocytes from mice of different ages: young (12 +/-2 weeks). adult (24 +/-2 weeks), mature (50 +/-2 weeks) and old (72 +/-2 wee ks) were used. Stimulation by NPY of NK activity was observed in adult and mature animals in axillary nodes and thymus, and an inhibition in the splee n from young mice. The specificity of the NPY effect on cytotoxic activity was confirmed using a C-terminal fragment of NPY. Furthermore, cAMP levels in leukocytes were found to be decreased by NPY in adult mice, suggesting a n involvement of this messenger system in the NK modulation by this neurope ptide. (C) 2001 Elsevier Science B.V. All rights reserved.