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

Abstract

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 [Leu 31,Pro 34]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 [Leu 31,Pro 34]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, [Leu 31,Pro 34]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.