Action and localization of neuropeptide Y in the human fallopian tube

Using indirect immunohistochemistry, neuropeptide Y-like immunoreactivity was found in nerve fibers around blood vessels and in the muscle layers of the human fallopian tube. Apart from a network of immunoreactive nerve fibers in connection with the luminary epithelium of the isthmus, the distribution resembled that of adrenergic, tyroxine hydroxylase immunoreactive, nerve fibers. Neuropeptide Y was found to have a dose-dependent inhibitory action on the adrenergic contractile response to field stimulation in the external longitudinal muscle layer of the isthmus. Furthermore, neuropeptide Y inhibited [3H]noradrenaline release from isthmic preparations during field stimulation, suggesting a prejunctional inhibitory action on adrenergic neurotransmission.