Neuropeptide Y 16-36 inhibits mucociliary activity but does not affect blood flow in the rabbit maxillary sinus in vivo

Recent investigations have shown neuropeptide Y (NPY) to be present in the rabbit maxillary sinus, and NPY is known to be released upon sympathetic nerve stimulation. To study, in vivo, the effect on mucociliary activity and blood flow, NPY 1-36 and some of its analogues were injected intra-arterially. The effects of the Y1/Y2 agonist NPY 1-36 was compared with the ones of the Y2 agonist NPY 16-36, the Y1-agonist [Leu31,Pro34]NPY and the Y1/Y2 agonist peptide YY. Mucociliary response was recorded photoelectrically and expressed as a percentage of the basal mucociliary activity immediately prior to challenge. The effect on blood flow was measured with laser Doppler flowmetry and expressed as a percentage of the mean blood flow during the 60 s preceding challenge. NPY 1-36 and NPY 16-36 both reduced mucociliary activity dose-dependently at equimolar dosages (0.024-1.2 nmol/kg). The greatest effect was seen after the highest dosage tested. NPY 1-36 reduced mucociliary activity by 14.6 +/- 1.8%, and NPY 16-36 by 13.2 +/- 1.4%. At the highest dosage tested the Y1 receptor agonist [Leu31,Pro34]NPY did not significantly reduce mucociliary activity, whereas PYY reduced mucociliary activity by 15.0 +/- 1.8%. Injections of NPY 16-36 had no effect on blood flow whereas NPY 1-36, [Leu31,Pro34]NPY and PYY all reduced blood flow dose-dependently. Maximal decrease was seen at the highest dosage tested and was 47.1 +/- 5.4%, 70.4 +/- 7.4% and 58.2 +/- 8.4%, respectively. These findings suggest the mucociliary effects to be mediated via Y2 receptors whereas blood flow is regulated via Y1 receptors.